Commodore VIC 1541 User Manual

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COMPUTER

VIC-1541

SINGLE DRIVE FLOPPY DISK

USER'S MANUAL

P/N 1540031-02

~ commodore

COMPUTER

WARNING: This equipment has been certified to comply with the limits for I!,
Class B computing device, pursuant to Subpart J of Part 15 of FCC Rules. Only
computers certified to comply with the Class B limits may be attached to this
printer. Operation with noncertified computers is likely to result in interference
to radio and TV reception,"

This warning is valid for the equipment which has the following FCC label
on its rear.

CERTIFIED TO COMPLY WITH CLASS B LIMITS.
PART 15 OF FCC RULES SEE INSTRUCTIONS IF
INTERFERENCE TO RADIO RECEPTION IS SUS-

PECTED.

The information in this manual has been reviewed and isbelievedto be entirely
reliable. No responsibility, however, is assumed for inaccuracies. The material in
this manual is for information purposes only, and is subject to change without

lIotice.

@Commodore BusinessMachines, Inc., September 1981

"All rights reserved."

Table of Contents

Page

1.

General Description

2.

Unpacking and Connecting .

Contents of Box . . ..

Connection of Cables

PoweringOn ........

Insertion of I)jskette . .. . .

Usingwith VlC 20 or Commodore 64 .

3.

UsingPrograms..............

Loading Pre-packaged Software

LOAD .

Directoryof Disk .. .. .. .. .

Pattern Matching & Wild Cards

SAVE .

SAVE and replace. . .

VERIFY.. .. . .. ..

DOS Support Program

4. Disk Commands . . . . . . . .

OPEN ANDPRINT #

NEW ...

COpy.. ..

RENAME.
SCRATCH
INITIALIZE
VAUDATE.

DUPUCATE

Reading the Error Channel
CLOSE

.. .. . .. . .. .. .

..............

3
6

6
7
7
8

.

8
9

9
9

9
11
12
13
13
14

14
14

IS

16

16

17

17
17
18
18
18

S.

SequentialFiles . . . . . . . . .

OPEN .

PRINT # and INPUT #

GET# ..

Reading the Directory

RandomFiles ..........

6.

Opening a channel for random accessdata

BLOCK-READ. . . . .

BLOCK-WRITE . . . .

BLOCK-ALLOCATE.

BLOCK-FREE . . . .

BUFFER-POINTER
USER 1 and USER2

19
19
20
22

23

.

26

27

27
28
29
29

31

32

7. RelativeFiles. .. ... .. .. . ... . . .. ., . 33

Creating arelative fde .. .. .. . .. .. . 34

Usingrelativefdes.. . . . . . . . . . . . . . . . . . . . . . . . . . . . .. 3S

8. Programming the Disk Controller. 37
BLOCK-EXECUTE 37

MEMORY-READ.. . . . . . . . . . . . . . . . . . . . . . . . . . . . .. 37

MEMORY-WRITE 38

MEMORY-EXECUTE . . . . . . . . . . . . . . . . . . . . . . . . . . ..

38

USERCommands 39

9. Changingthe Disk Device Number .. . . .. . . . .. . . .. . . .. . . ... 39

Software Method .. . . . . . . . . . . . . . . . . . . . . . . . . . . . .. 39

HardwareMethod 40

Appendices

A. DiskCommandSummary. 41

B. ErrorMessages. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. 42

C. Demonstration Disk Programs

D. DiskFormatsTables .. . . . . . . . . . . . .. . . . . . . . . . . . . .. S4

. . .. . . . . . . .. . . .. . . .. . .. 47

2

1. GENERAL DESCRIPTION

Introduction

Welcome to .the fastest, easiest, and most efficient filing system available
for your Commodore 64 or VIC 20 computer, your 1541 DISK DRIVE. This
manual has been designed to show you how to get the most from your drive,
whether you're a beginner or an advanced professional.

If you are a beginner, the first few chapters will help you through the

basics of disk drive installation and operation. As your skill and programming
knowledge improves. you will find more uses for your disk drive and the more
advanced chapters of this manual willbecome much more valuable.

If you're a professional, this reference guide will showyou how to put the
1541 through its paces to perform just about all the disk drive jobs you can

think of.

No matter what level of expertise you have, your 1541 disk drive will

dramatically improve the overall capabilities of your computer system.

Before you get to the details of 1541 operation, you should be aware of a
few important points. This manual is a REFERENCE GUIDE, which means that
unless the information you seek directly pertains to the disk or disk drive you
will have to useyour Commander 64 or VIC 20 User's Guides and Programmer's
Reference Guides to find programming information. In addition, even though we

give you step-by-step instructions for each operation, you should become

familiar with BASIC and the instructions (called commands) that help you
operate your disks and drives. However. if you just want to use your disk drive

unit to load and save prepackaged software, we've included an easy and brief

section on doingjust that.

Now. . . let's get on with the general information.

The commands for the disk drive come in several levels of sophisication.
Starting in chapter three. you can learn how the commands that allow you to
save and load programs with the disk work. Chapter four teaches you how

commands are sent to the disk, and introduces the disk maintenance commands.

Chapter five tells you how to work with sequential data files. These arl
very similar to their counterparts on tape (but much faster). Chapter sif

introduces the commands that allow you to work with random files, accessany
piece of data on the' disk, and how you organize the diskette into tracks and

blocks. Chapter seven describes the special relative files. Relative files are the
best method of storing data bases, especially when they are used along with
sequential files.

Chapter eight describes methods for programming the disk controller

circuits at the machine language level. And the final chapter shows you how to

3

change the disk device number. by "cutting" a line inside the drive unit or
through software.

Remember, you don't really need to learn everything in this book all at

once. The first four chapters are enough to get you going, and the next couple
are enough for most operations. Getting to know your disk drivewill reward you
in many ways-speed of operation, reliability, and much more flexibility in your

data processing capabilities.
Specifications

This disk drive allows you to store up to 144 different programs and/or

data files on a singlemini-floppy diskette, for a maximum of over 174,000 bytes
worth of information storage.

Included in the drive is circuitry for both the disk controller and a

complete disk operating system, a total of 16K of ROM and 2K of RAM
memory. This circuitry makes your Commodore 1541 disk drive an "intelligent"

device. This means it does its own processing without taking any memory away
from your Commodore 64 or VIC 20 computer. The disk uses a "pipeline"

software system. The "pipeline" makes the disk abot to process commands while

the computer is performing other jobs. This dramatically improves the overall
throughput (input and output) of the system.

Diskettes that you create in this disk drive are read and write compatible

with Commodore 4040 and 2031 disk drives. Therefore, diskettes can be used
interchangeably on any of these systems. In addition, this drive can read

programs created on the older Commodore 2040 drives.

The 1541 disk drive contains a dual "serial bus" interface. This bus was

specially created by Commodore. The signals of this bus resemble the parallel
IEEE-488 interface used on Commodore PET computers, except that only one
wire is used to communicate data instead of eight. The two ports at the rear of

the drive allows more than one device to share the serial bus at the same time.
This is accomplished by "daisy-chaining" the devices together, each plugged into

the next. Up to fivedisk drivesand one printer can share the bus simultaneously.

4

Figure 1.1 Specifications VIC 1540/1541 Single Drive Floppy Disk

STORAGE

Total capacity

Sequential
Relative

Directory entries
Sectors per track

Bytes per sector
Tracks

Blocks

lC's:

6502
6522 (2)

Buffer

2114 (4)

PHYSCIAL:

Dimensions

Height
Width

Depth

Electrical:

Power requirements

Voltage

Frequency

Power

174848 bytes per diskette
168656 bytes per diskette
167132 bytes per diskette
65535 records per file
144 per diskette

17 to 21
256

35
683 (664 blocks free)

microprocessor
I/O. internal timers

2K RAM

97mm
200 mm
374 mm

I

O, 120,220, or 240 VAC

5 or 60 Herts

~

2 Watts

MEDIA:

Diskettes

Standard mini 5\4", singlesided,

singledensity

5

2. UNPACKING AND CONNECTING

Contents of Box

power cable, black serial bus cable, this manual, and a demonstration diskette.

The power cable has a connection for the back of the disk drive on one end, and

for a grounded (three-prong) electrical outlet on the other. The serial bus cable is

exactly the same on both ends. It has a 6-pin DIN plug which attaches to the

VIC 20, Commodore 64 or another disk drive.

section!

Fig 1. Front Panel LIGHT:POWERON

Fig2. BackPanel

Included with the 1541 disk drive unit, you should find a gray

Please, don't hook up anything until you've completed the following

(: commodare_ floppy disk ~ VIC. 541

_single drive

DRIVE INDICATER (RED LED)

POWER INDICATER
(GREEN LED)

POWER SWITCH

LIGHT: ACTIVE
FLASH: ERROR

,

SERIAL BUS

6

Connection of Cables

Your first step is to take the power cable and insert it into the back of the

disk drive (see figure 2.2). It won't go in if you try to put in in upside down.

Once it's in the drive, plug the other end into the electrical outlet. if the disk
drive makes any sound at this time, please turn it off using the switch on the
back! Don't plug any other cables into the disk drive if the power is on.

Next. take the serial bus cable and attach it to either one of the serial bus
sockets in the rear of the drive. Turn off the computer, and plug the other end
of the cable into the back of the computer. That's all there is to it!

If you have a printer, or any additional disk drives, attach the cables into
the second serial bus port (see figure 2.3). For directions on using multiple drives
at one time, read chapter 8. If you are a first-time user with more than one drive,
start working with only one drive until you're comfortable with the unit.

---_.--_.-.---._-_..

r u --- ..---.--.

I

Powering On

When you have all the devices hooked together, it's time to start turning
on the power. It is important that you turn on the devices in the correct order.
The computer should always be turned on last. As long as the computer is the
last one to be turned on, everything will be OK.

Commodore 64 or VIC20

Personal Computer

VIC Graphic Printer

Fig 3. Floppy Disk Hookup

VIC 1541
Single Drive
Floppy Disk

l

I
i

7.

First, make sure that you've removed all diskettes from the disk drives
before powering on.

After all the other deviceshave been turned on, only then is it safe to turn

on the computer. All the other devices will go through their starting sequences.

The printer's motor goes on, with the print head movinghalfway across the line

and back again. The 1541 disk drive will have its red error light on, and then the
green drivelight will blink, whileyour TV screen forms the starting picture.

Once all the lights have stopped flashing on the drive, it is safe to begin

working with it.

Z

In

m
:c

'-I

z

WRITE

PROTECT

NOTCH

WHEN COVERED. DISKETTE
CONTENTS CANNOT BE
AL TERED

~ <:

~ m

=

-I

o
o

:c

Fig.4. Position for Diskette Insertion

Insertion of Diskette

To open the door on the drive, simply press the door catch lightly, and the
door will pop open. If there is a diskette in the drive, it is ejected by a small
spring. Take the diskette to be inserted, and place it in the drive face-up with the

large opening going in first and the write-protect notch to the left (covered with

tape in the demonstration disk) (see figure 2.4).

Press it in gently, and when the diskette is in all the way, you will feel a
click and the diskette will not spring out. Close the drive door by pulling
downward until the latch clicks into place. Now you are ready to begin working

with the diskette.

Remember to always remove the diskette before the drive is turned off or
on. Never remove the diskette when the green drive light is on! Data can be

destroyed by the drive at this time!
UsingWith a VIC 20 or Commodore 64

The 1541 Disk Drive can work with either the VIC 20 or Commodore 64

8

computers. However, each computer has different requirements for speed of
incoming data. Therefore, there is a software seitch for selecting which
computer's speed to use. The drive starts out ready for a Commodore 64. To
switch to VIC 20 speed, the foIlowing command must be sent after the drive is
started (power-on or through software):

OPEN 15,8,15, "UI-": CLOSE 15

To return the disk drive to Commodore 64 speed, use this command:

OPEN 15,8, 15, "UI+": CLOSE 15

More about using this type of command is in chapter 4, with a detailed

explanation of the U (user) commands in chapter 7.

3. USING PROGRAMS

LOADINGPREPACKAGED PROGRAMS

For those of you interested in using only prepackaged programs available

on cartridges, cassette, or disk, here's all you have to do:

Usingyour disk drive, carefully insert the preprogrammed disk so that the
label on the disk is facingup and isclosest to you. Look for a little notch on the
disk (it might be covered with a little piece of tape). If you're inserting the disk
properly, the notch will be on the left side. Once the disk is inside, close the
protective gate by pushing in on the lever. Now type LOAD "PROGRAM
NAME", 8 and hit the .~U"IU~~. key. The disk will make noise and your
screen willsay:

When the READY comes on and the:~:is on, just type RUN, and your

prepackaged software is ready to use.

LOAD

The BASICcommands used with programs on the disk drive are the same

as the commands used on the Commodore DatassetteTM recorder. There are a

few extra commands available for use with disks, however. First of all, the
program name must be given with each command. On a Datassette, you could
omit the program name in order to just LOAD the firs program there. On disk,
since there are many different programs that are equally accessible, theprogram

9

name must be used to tell the disk drive what to do. In addition, the disk drive's

device number must be specified. If no device number is listed, the computer

assumes the program is on tape.

FORMAT FOR THE LOAD COMMAND:

LOAD name$ , device# , command#

The program name is a string, that is, either a name in quotes or the
contents of a given string variable. Some valid names are: "HELLO",
"PROGRAM #1", A$, NAME$.

The device# is preset on the circuit board to be #8. If you have more than
one drive, seechapter 8 on how to change the devicenumber. This book assumes
that you're using devicenumber 8 for the disk drive.

The command# is optional. If not given, or zero, the program is LOADed
normally, that is, beginning at the start of your available memory for BASIC
programs. If the number is I, the program will be LOADed at exactly the same
memory locations from which it came. In the case of computers with different
memory configurations, like VICs with 5K, 8K, or more memory, the start of
BASIC memory is in different places. The command# 0 permits BASIC
programs to LOAD normally. Command# I is used mainly for machine
language, character sets, and other memory dependent functions.

EXAMPLES

LOAD "TEST", 8

LOAD"Mach Lang", 8, I

NOTE: You can use variables to represent devicenumbers, commands, and
strings, as long as you've previously defined them in your program.

Directory of Diskette

Your Datassette™ tape deck is a sequential device. It can only read from
the beginning of the tape to the end, without skipping around the tape and
without the capability of goingbackward or recording over old data.

Your disk drive is a random access device. The read/write head of the disk

can go to any spot on the disk and access a single block of data which holds up

to 256 bytes of information. There are a total of 683 blocks on a single diskette.

.Fortunately, you don't really have to worry about individual blocks of
data. There is a program in the disk drive called the Disk Operating System, or
the DOS. This program keeps track of the blocks for you. It organizes them into

a Block Availability Map,or BAM,and a directory.
10

The Block Availability Map is simply a checklist of all 683 blocks on the
disk. It is stored in the middle of the diskette, halfway between the center hub
and the outer rim. Every time a program is SAVEd or a data file isCLOSEd, the
BAMis updated with the list of blocks used up.

The directory is a list of all programs and other files stored on the disk. It
is physically located right next to the BAM.There are 144 entries available in
the directory, consisting of information like file name and type, a list of blocks
used, and the starting block. The directory is automatically updated every time a
program is SAVEd or a file is OPENed for writing. Beware: the BAM isn't
updated until the file is CLOSEd, even though the directory changes right away.
If a file isn't CLOSEdproperly, all data in that me will probably be lost.

The directory can be LOADed into your memory just like a BASIC
program. Place the diskette in the drive, and type the following command:

LOAD"$",8

The computer responds with:

Now the directory is in your computer's memory. Type LIST, and you'll
see the directory displayed on the screen. To print the directory on your printer,

type the following command line (in this example your printer is plugged in as

device# 4):

OPEN4, 8,4: CMD4: LIST

NOTE: When using CMD, the file must be closed using the command

PRINT# 4: CLOSE 4. See the VIC 1525/1515 printer manual for detailed

explanation.

To read the directory without LOADing it into your memory, see the

section later in this chapter on the DOS Support Program. In addition, to
examine the directory from inside a BASICprogram. see the section in chapter 5

that deals with the GET# statement.

Pattern Matching and Wild Cards

When using the tape deck, you can LOAD any program starting with

certain letters just by leaving off any following letters. Thus, the command

11

LOAD "T" will find the first program on the tape beginning with the letter T.
And LOAD "HELLO" will find the first program beginning with the letters
HELLO, like "HELLO THERE."

When using the disk, this option is called pattern matching, and there is a
special character in the file name used to designate this. The asterisk (*)
character following any program name tells the drive you want to find any
program starting with that name.

FORMAT FOR PATTERN MATCHING:

Can BeA String
Variable Or The

LOADname$ + "*", 8

Name Inside Quotes

In other words, if you want to LOAD the first program on the disk
starting with the letter T, use the command LOAD "T*", 8.

If only the "* is used for the name, the last program accessedon the disk
is the one LOADed. If no program has yet been LOADed, the first one listed in
the directory is the one used.

You are probably familiar with the concept of wild cards in poker where
one card can replace any other card needed. ,On your 1541, the question mark
(?) can be. used as a wild .card on the disk. The program name on the disk is
compared to the name in the LOAD command, but any characters where there is

aquestionmarkinthe namearen't checked. '

For instance, when the command LOAD "T?NT", 8 is given, programs

that match include TINT, TENT, etc.

When LOADingthe directory of the disk, pattern matching and wild cards
can be used to check for a list of specific programs. If you gave the command
LOAD "$O:TEST", only the program TEST would appear in the directory (if
present on the disk). The command LOAD "$O:t*" would giveyou a directory
of aUprograms beginning with the letter T. And LOAD "$O:T?ST" would give

you all the programs with 4-letter names having the first letter of T and the third

and fourth letters ST. LOAD "$O:T?ST*" would give names of any length with
the correct first, third, and fourth letters.

SAVE

To SAVE a program to the diskette, all that is needed is to add the device
number after the program name. Just like the SAVE command for the tape
deck, the device number can be folJowedby a command number, to prevent the

automatic re-Iocation on LOADing (see the section on the LOAD 'command,
above).

FORMAT FOR THE SAVE COMMAND:

SAVE name$, device#, command#

12

&

See the LOAD ~ommal1d (pages

parameters device# and command#.

When you tell the disk drive to SAVE a program, the DOS must take
several steps. First, it looks at the directory to see if a program with that name
already exists. Next it ~he~ks to see that there is a directory entry availablefor
the name. Then it che~ks the BAMto see if there are enough blocks in which to
store the program. If everything is OKup to this point, the program is stored. If
not, the error light willflash.

SAVE and Replace

If a program already exists on the disk, it is often necessary to make a
~hange and re-SAVE it onto the disk. In this case, it would be inconvenient to
have to erase the old version of the program and then SAVE it.

If the first characters of the program name are the "(aP'signfollowed by a
o and a colon (:), the DOS knows to replace any old program that has that name
with the program that is now in the computer's memory. The drive checks the
directory to find the old program, then it marks that entry as deleted, and it
next creates a new entry with' the same name. Finally, the program is stored
normally.

FORMAT FOR SAVE WITHREPLACE:

SAVE "=0:" + nameS, device#, command#

For example, if a file was called TEST, the SAVE and replace command
would be SAVE"(u,O:TESr,8.

) for an explanation of the

____

The reason for the 0: is to keep compatibility with other Commodore disk
drive units which have more than one drive built in. In that case, the number 0

or 1is used to specify which drive isbeing used.
VERIFY

The VERIFY command works to check the program currently in memory

against the program on disk. You must include a device# with the VERIFY

command. The computer does a byte-by-byte comparison of the program,

including line links-which may be different for different memory configura-
tions. For instance, if a program was SAVEd to disk from a 5K VIC 20, and
re-LOADed on an 8K machine, it wouldn"t VERIFY properly because the links
point to different memory locations.

FORMAT FOR VERIFY COMMAND:

VERIFY name$, device#

I3

DOS Support Program

On your demonstration

disk, there may be a program called DOS

SUPPORT.This program, also called a wedge,allowsyou to use many disk

commands more easily (different wedges are used for the VIC 20 and the
Commodore 64). Just LOAD the program and RUN it. It automatically sets

itself up and erases itself when it's finished. You'll have a few hundred less bytes
to work with when this program is running, but you'll also have a handy way to

send the disk commands.

As a result of the DOS Support, the "/" key now takes the place of the
LOAD command. Just hit the slash followed by the program name, and the
program is LOADed. When you use this method, you don't need to use the

LOADcommand or the comma 8.

Thc"(Q)"and ">" keys are used to send commands to the disk drive. If you
type (a$ (or >$), the directory of the disk is displayed on the screen, without

LOADinginto your memory! Thesekeysalsotaketheplaceof thePRINT#(see

chapter 4) to send commands listed in the next chapter.

To read the error channel of the disk (when the red error light is blinking),

just hit either the (a'or the> and hit RETURN. The complete error message is

displayed to you: messagenumber, text, and track and block numbers.

4: DISK COMMANDS

OPEN and PRlNT#

Up 'til now, you have explored the simple ways of dealing with the disk

drive. In order to communicate with the disk drive more fully, you have to
touch on the OPEN and PRINT# statements in BASIC(more details of these
commands are available in your VIC 20 or Commodore 64 User's Guide or

Programmer's Reference Guide). You may be familiar with their use with data
files on cassette tape, where the OPEN statement creates the file and the
PRINT# statement fills the file with data. They can be used the same way with

the disk, as you will see in the next chapter. But they can also be used to set up
a command channel. The command channel lets you exchange information
between the computer and the disk drive.

FORMAT FOR THE OPEN STATEMENT:

OPENfile#, device#, (command) channel#, text $

The file# can be any number from I to 255. This number is used

throughout the program to identify which file is being accessed. But numbers

greater than 127 should be avoided, because they cause the PRINT# statement
to generate a linefeed after the return character. These numbers are really meant

to be used withnon-standard printers.
14

The device# of the disk is usually 8.
The channel # can be any number from 2 to 15. These refer to a channel

used to communicate with the disk, and channels numbered a and I are reserved
for the operating system to use for LOADingand SAVEing.Channels::: through

14can be used for data to files, and 15is the command channel.

The text$ is a string that is PRINTed to the file, as if with a PRINT#

statement. This ishandy for sending a single command to the channel.

EXAMPLES OF OPEN STATEMENTS:

~

OPEN 15,8, IS DEViCE-#~\

~

OPEN2,8. 2 C-- ~~

OPENA;B,C,ZL ~

The PRINT# command works exactly like a PRINT statement, except

that the data goes to a deviceother than the screen, in this case to the disk drive.

When used with a data channel, the PRINT# sends information into a buffer in

the disk drive, which LOADs it onto the diskette. When PRINT# is used with
the command channel, it sends commands to the disk drive.

FORMAT FOR SENDING DISK COMMANDS:

OPEN 15, 8, IS. command$

or

PRINT# IS, command$

NEW

This command is necessary when using a diskette for the first time. The
NEW command erases the entire diskette, it puts timing and block markers on
the diskette and creates the directory and BAM.The NEWcommand can also be
used to clear out the directory of an already.formatted diskette. This is faster
than re-formatting the whole disk.

FORMAT FOR THE NEWCOMMANDTO FORMATDISK:

PRINT#15, "NEW~~'

or abbreviated as

PRINT#15, "N~:name,id"

FORMAT FOR THE NEW COMMAND TO CLEAR DIRECTORY:

PRINT# 15, "N~:name"

The name goes in the directory as the name of the entire disk. This only

appears when the directory is listed. The ID code is any 2 characters, and they
are placed not only on the directory but on every block throughout the diskette.

15

That way, if you carelessly replace diskettes while writing data, the drive will
know by checking the ID that something is wrong.

COpy

This command allows you to make a copy of any program or file on the
disk drive. It won't copy from one drive to a different one (except in the case of
dual driveslike the 4040), but it can duplicate a program under another name on

the drive.

FORMAT FOR THE COPYCOMMAND:

PRINT# 15, "COPY~:newfile=~:oldfile"
or abbreviated as

PRINT# 15, "c~:newfile=~:oldfile"

The COpy command can also be used to combine two through four flles

on the disk.

FORMAT FOR COpy TO COMBINE FILES:

PRINT#15, "CO: newfile=O: old file I,0:0Idfile2,0:0Idfile3 ,0:0Idfile4"

EXAMPLES OF COPY COMMAND:

PRINT# 15, "CO:BACKUP=O:ORIGINAL"

PRINT#15, "CO:MASTERFILE=O:NAME,O:ADDRESS,O:PHONES"

RENAME

~ "'"

This command allows you to change the name of a file once it is in the
disk directory. This is a fast operation, since only the name in the directory must

be changed.

FORMAT FOR RENAME COMMAND:

~-~

PRINT# IS, "RENAME~:newname=oldname" ~

or abbreviated as

PRINT# IS, "R~:newname=oldname"
EXAMPLE

OPEN.

16

OF RENAME COMMAND:

PRINT# 15, "RO:MYRA=MYRON"

The RENAME command willnot work on any files that are currently

SCRATCH

This command allows you to erase unwanted files and programs from the

disk, which then makes the blocks available for new information. You can erase
programs one at a time or in groups by using pattern matching and/or wild cards.

FORMAT FOR SCRATCHCOMMAND

PRINT# 15,"SCRATCH~:~

or abbreviated as

PRINT# 15, "S~:name"

If you check the error channel after a scratch operation (see below), the
number usually reserved for the track number now tells you how many files
were scratched. For example, if your directory contains the programs KNOW
and GNAW, and you use the command PRINT# 15, "SO:?N?W", you will
scratch both programs. If the directory contains TEST, TRAIN, TRUCK, and
TAIL, and you command the disk to PRINT# 15, "SO:T*", you will erase all
four of these programs.

INITIALIZE

At times, an error condition on the disk willprevent you from performing
some operation yo~ want to do. The INITIALIZE command returns the disk
drive to the same state as when powered up. You must be careful to re-match
the drive to the computer (see chapter 2).

FORMAT FOR INITIALIZE COMMAND:

PRINT# 15,"INITIALIZE"
or abbreviated as

PRINT# 15, ''!''

VALIDATE

After a diskette has been in use for some time, the directory can become
disorganized. When programs have been repeatedly SAVEd and SCRATCHed,
they may leave numerous small gaps on the disk, a block here and a few blocks
there. These blocks never get used because they are too small to be useful. The
VALIDATE command will go in and re-organize your diskette so that you can
get the most from the availablespace.

Also, there may be data files that were OPENed but never properly
CLOSEd. This command will collect all blocks taken by such files and make
them available to the drive, sincethe files are unusable at that point.

There is a danger in using this command. When using random files (see
chapter 6), blocks allocated will be de-allocated by this command. Therefore,
this command should never be used with a diskette that usesrandom files.

17

FORMAT FOR VALIDATE COMMAND:

PRINT# 15, "VALIDATE"

or abbreviated as

PRINT# 15, "V"

DUPLICATE

This command is a hangover from the operating systems that were

contained on the dual drives like the 4040. It was used to copy entire diskettes

from one drive to another, but has no function on a singledisk drive.

Reading the Error Channel

Without the DOS Support Program, there is no way to read the disk error
channel without a program, since you need to use the INPUT# command which
won't work outside a program. Here is a simple BASICroutine to read the error

channel:

IOOPENI5,8,15 /' ~E

20 INPUT# 15,A$, B$,C~

30 PRINT A$, B$, C$, D$ ~

Whenever you perform an INPUT# operation from the command channel,

you read up to 4 variables that describe the error condition. The first, third, and

fourth variables come in asnumbers, and can be INPUT into numeric variables if

you like. The first variable describes the error #, where 0 is no error. The second
variable is the error description. The third variable is the track number on which

the error occurred, and the fourth and final is the block number inside that
track. (A block isalso known asa sector)

Errors on track 18have to do with the BAMand directory. For example, a
READ ERROR on track 18 block 0 may indicate that the disk was never
formatted.

CLOSE

It is extremely important that you properly CLOSE files once you are

finished using them. Closing the file causes the DOS to properly allocate blocks
in the BAMand to finish the entry in the directory. If you don't CLOSE the fde,
aDyour data will be lost!

FORMAT FOR CLOSE STATEMENT:

CLOSE file#

You should also be careful not to CLOSE the error channel (channel# 15)

18

before CLOSEingyour data channels. The error channel should be OPENed iust

and CLOSEd last of all your files! That will keep your programs out of trouble.

If you close the error channel while other files are OPEN, the disk drive

will CLOSE them for you, but BASIC will still think they are open (unless you

CLOSE them properly), and let you to try to write to them.

NOTE: If your BASIC program leads you into an error condition, all files
are CLOSEd in BASIC,without CLOSEing them on your disk drive! This
is a very dangerous condition. You should immediately type the statement
CLOSE 15: OPEN 15, 8, 15: CLOSE 15. This will re-initializeyour drive
and make allyour files safe.

5. SEQUENTIAL FILES
OPEN

Sequential files on the disk drive work exactly like they do on cassette
tape, only much faster. They are limited by their sequential nature, which means
they must be read from beginning to end. Data is transferred byte by byte,
through a buffer, onto the magnetic media. To the disk drive all filesare created
equal. That is, sequential files, program files, and user filesall work the same on
the disk. Only program files can be LOADed, but that's really the only
difference. Even the directory works like this, except that it is read-only. The
only difference is with relative files.

FORMAT FOR OPENING A SEQUENTIAL FILE:

OPEN file#, device#, channel#, "O:name,type,direction"

The file number is the same as in allyour other applications of the OPEN
statement, and it is used throughout the program to refer to this particular file.
The device# is usually 8. The channel# is a data channel, number 2 through 14.
It is convenient to use the same number for both the channel# and file#, to
keep them straight. The name is the file name (no wildcards or pattern matching
if you're creating a write file). The type can be any of the ones from the chart
below, at least the first letter of each type. The direction must be READ or
WRITE,or at least the first letter of each.

FILE TYPE MEANING

PRG

SEQ
USR
REL

Program
Sequential
User

Relative (not implemented in BASIC2.0)

19

EXAMPLES OF OPENING SEQUENTIAL FILES:

If the me alreadyexists,you can use the replaceoption in the OPEN

statement, similarto the SAVE-and-replacedescribedin chapter3. Simplyadd
the(0'0:beforethe file'snamein theOPENstatement.

EXAMPLE OF SEQUENTIAL FILE WITH REPLACE OPTION:

OPEN 2, 8, 2, "(Q?():DATA,S,W"

PRINT#andINPUT#.

The PRINT# command works exactly like the PRINT statement, except
that output is re-directed to the disk drive. The reason for the special emphasis
on the word exactly is that all the formatting capabilities of the PRINT
statement, as applies to punctuation and data types, applies here too. It just
means that you have to be careful when putting data into your files.

FORMAT FOR WRITING TO FILE WITH PRINT#:

PRINT# file#, data list

The file# is the one from the OPEN statement when the file wascreated.

The data list is the same as the regular PRINT statement-a list of variables

and/or text inside quote marks. However, you must be especially careful when

writing data that it is aseasy as possible to read back againlater.

When using the PRINT# statement, if you use commas (,) to separate

items on the line, the items will be separated by some blank spaces,as if it were
being formatted for the screen. Semicolons (;) don't result in any extra spaces.

In order to more fully understand what's happening, here is a diagram of a

sequential file created by the statement OPEN 5, 8, 5, "O:TEST,S,W":

char

The eof stands for the end-of-me marker. String data entering the file goes

in byte by byte, including spaces.

For instance, let's set up some variables with the statement A$=

"HELLO"; B$= "ALL": C$= "BYE". Here is a picture of a me after the

20

statement PRINT# 5, A$; B$; C$:

char

CR stands for the CRR$ code of 13, the carriagereturn, which isPRINTed

at the end of every PRINT or PRINT# statement unless there is a comma or
semicolon at the end of the line.

NOTE: Do not leave a space between PRINT and #, and do not try to

abbreviate the command as ?#. See the appendixes in the user manual for
the correct abbreviation.

FORMAT FOR INPUT#STATEMENT:

INPUT# file#, variable list

When using the INPUT# to read this data in, there is no way to tell that
it's not supposed to be one long string. You need something in the file to act as a
separator. Characters to use as separators include the CR, a comma or a
semicolon. The CR can be added easily by just uSingone variable per line on the
PRINT# statement, and the system pUtsone there automatically. The statement
PRINT# 5, A$: PRINT# 5, B$: PRINT# 5, C$ puts a CR after every variable
being written, providing the proper separation for a statement like INPUT#5,

AS, B$, C$. Or else a line like Z$=..,": PRINT# 5, A$ Z$ B$ Z$ C$ willdo the

job as well, and in lessspace. The file after that line looks like this:

char

Putting commas between variablesresults in lots of extra space on the disk

being used. A statement like PRINT# 5, A$, B$ makes a filethat looks like:

char

You can seethat much of the space in the file is wasted.

The moral of all this is: take care when usingPRINT# so your data will be

in order for reading back in.

Numeric data written in the file takes the form of a string, as if the STR$
function had been performed on it before writing it out. The first character will
be a blank space if the number is positive, and a minus sign (-)if the number is
negative. Then comes the number,and the last character is the cursor right
character. This format provides enough information for the INPUT# statement
to read them in as separate numbers if several are written with no other special
separators. It is somewhat wasteful of space, since there can be two unused

21

characters if the numbers are positive.

Here is a picture of the file after the statement PRlNT# 5, I; 3; 5; 7 is

performed:

char IS

Appendix B contains a program demonstrating the use of a sequential disk

fIle.
GET#

The GET# retrieves data from the disk, one character at a time.

FORMAT FOR THE GET# STATEMENT:

GET# f1le#, variable list

Data comes in byte by byte, including the CR, comma, and other

separating characters. It is much safer to use string variables when using the
GET# statement. You will get a BASICerror message if string data is received

where a number was requested, but not vice-versa.

EXAMPLES OF GET#STATEMENT:

GET# 5, A$

You can get more than I character at a time

GETS 5, A

The GET# statement is extremely useful when examining files with
unknown contents, like a file that may have been damaged by an experimental
program. It is safer than INPUT# because there is a limit to the number of
characters allowed between separators of INPUT variable.s.With GET#, you
receiveevery character, and you can examine separators as well asother data.

Here is a sample program that will allow you to examine any file on the

disk:

10 INPUT "FILE NAME"; F$
20 INPUT "FILE TYPE";T$
30 T$=LEFTS(TS,1)

40 IF TS < > "s" THEN IF T$ < > "P" THEN IF T$ < > "u" THEN 20

45 OPEN 15,8,15
50 OPEN5,8,5, "0:" + F$+ ","+ T$+ ",R"

60 GOSUB200

22

70 GET# 5, A$

80 IF ST< > 0 THENPRINT ST: STOP

90 PRINT ASC(A$+CHR$.l0) );

100 GOTO 70
200 INPUT# 15, A$, B$, C$, 0$
210 IF VAL (A$) > 0 THEN PRINT A$,B$,C$;O$:STOP

220 RETURN

Reading the Directory

The directory of the diskette may be read just like a sequential file. lust
use $ for the file name, and OPEN 5, 8, 5, "$". Now the GET# statement works
to examine the directory. The format here is identical to the format of a
program file: the file sizes are the line numbers, and names are stored as
characters within quote marks.

Here's aprogram that lets you read the directory of the diskette:

100PENl,8,2,"S

20 GET#I,A$,A$,A$,A$

30 T$(O) ="Del":T$(1) ="SEQ":T$(2) ="PRG":T$(3) ="USR":T$(4) ="REL"

401=17:GOSUBSOO ~~

601=2 ( ID

50N$=B$ @) ~

70 GOSUB500

In CaseOf Null
Character Being

Read In
Error With ASC
Function Otherwise!

- Causes

801$=B$
901=2

100 GOSUB500

( ( OPERATINGSYSTEM

1100$=B$

120FORL=IT073( (GETRESTOFBLOCK

130GET#I,A$,A$,A$
140NEXT

150GET#I,A$,A$,A$,A$,A$
160PRINTCHR$(147)

"Diskname:"N$,"ID: "I$,"OS: "0$

161 PRINT"Length" ,"Type" ,"Name"
165 FORP=IT08

170 GET#l ,T$,A$,A$
175IFSTTHENCLOSEl:END

180IFT$=""THENT$=CHR$(128)
1901=15

( ~

200 GOSUB500 ~

210N$=B$ ~

220GET#1,A$,A$,A$,A$,A$,A$,A$,A$,A$,A$,U,H$

225 L=ASC(U+CHR$(0))+25 6*ASC(H$+CHR$(0):IFL=OTHEN250
230 PRINTL,T$(ASC(T$)-128),N$
250 IFP < 8THENGET#1 ,A$,A$

260NEXTP:GOTOI65

23

500 B$=""
510 FORL=OTOJ

520 GET#I,A$ BUILD A
530 IFA$ < > CHR$(96)THENIFA$ < > CHR$(160)THENB$=B$+A$f STRING

540 NEXT ~SUBROUTINE
550 RETURN

Table 5.1: 1540{1541 BAM FORMAT

Track 18, Sector O.

BYTE CONTENTS
0,1 18,01

2 65
3 0
4-143

... 1 =available block

o =block not available

(each bit represents one block)

Table 5.2: 1540/1541 DIRECTORY HEADER

Track 18, Sector O.

BYTE CONTENTS DEFINITION

144-161

162-163 Disk lD.
164
165,166

166-167 160
171-255 0

160

50,65

Track and sectOrof first directory block
ASCIIcharacter A indicating 4040 format.
Null flagfor future OOSuse.
Bit map of available blocks for trac so1-35.

Disk name padded with shifted spaces.

Shifted space.
ASCII representation for 2A which is DOSversion

and format type.
Shifted spaces.
Nulls, not used.

DEFINITION

j

Note: ASCIIcharacters may appear in locations 180 thru 191 on some diskettes.

24

Table 5.3: DIRECTORY FORMAT

18,Sector1for4040

Track

Track 39, Sector 1 for 8050

BYTE

0,1
2-31
34-63

66-95
98-127

130-159

162-191

194-223

226-255

BYTE

0

1,2
3-18

19,20

21
22-25

26,27

28,29

DEFINITION

Track and sector of next directory block.
*File entry 1
*File entry 2
*File entry 3
*File entry 4
*File entry 5
*File entry 6

*File entry 7
*File entry 8

*STRUCTURE OF SINGLE DIRECTORY ENTRY

CONTENTS DEFINITION

128+type

File type OR'ed with $80 to indicate properly closed
file.

TYPES: 0= DELeted

I = SEQential

2 =PROGram

3=USER

4 = RELative
Track and sector of 1st data block.
File name padded with shifted spaces.
Relative file only: track and sector for first side sector

block.
Relative file only: Record size.

Unused.

Track and sector of replacement file when OPEN(a)is in
effect.

Number of blocks in file: low byte, high byte.

25

Table 5.4: SEQUENTIAL FORMAT

BYTE DEFINITION

0,1
2-256

Track and sector of next sequential data block.
254 bytes of data with carriage returns as record terminators.

Table 5.5: PROGRAM FILE FORMAT

BYTE

0,1
2-256

Track and sector of next block in program me.
254 bytes of program info stored in CBMmemory format (with

key words tokenized). End of file is marked by three zero bytes.

DEFINITION

6. RANDOMFILES

Sequential files are fine when you're just working with a continuous
stream of data, but some jobs require more than that. For example, with a large
mailing list, you would not want to have to scan through the entire list to find a
person's record. For this you need some kind of random access method, some
way to get to any record inside a file without having to read through the entire

fIle first.

There are actually two different types of random access files on the
Commodore disk drive. The relative files discussed in the next chapter are more
convenient for data handling operations, although the random files in this
chapter have uses of their own, especially when working with machine language.

Random files on the Commodore disk drive reach the individual 256.byte
blocks of data stored on the disk. As was mentioned in the first chapter, there
are a total of 683 blocks on the diskette, of which 664 are free on a blank
diskette. Each block of data really means I Track and sector of the same name.

The diskette is divided into tracks, which are laid out as concentric circles
on the surface of the diskette. There are 35 different tracks, starting with track I

at the outside of the diskette to track 35 at the center. Track 18 isused for the

directory, and the DOS fills up the diskette from the center outward.

Each track is subdivided into sectors. Because there is more room on the
outer tracks, there are more sectors there. The outer tracks contain 21 sectors
each, while the inner ones only have 17 blocks each. The table below shows the
number of sectors per track.

26

TRACK NUMBER SECTORRANGE

I to [7

o to 20

18 to 24 o to 18

25 to 30
31 to 35

o to 17 18

o to 16

TOTAL SECTORS

21

19

17

The DOS contains commands for reading and writing directly to any track
and sector on the diskette. There are also commands for checking to see which
blocks (tracks & sectors) are available,and for marking off used blocks.

These commands are transmitted through the command channel

(channe[# 15), and tell the disk what to do with the data. The data must be read

later through one of the open data channels.
Opening a Data Channel for Random Access

When working with random accessfiles, you need to have 2 channels open

to the disk: one for the commands, and the other for the data. The command
channel is OPENed to channel 15, just like other disk commands you've

encountered so far. The data channel for random access files is OPENed by
selecting the pound sign (#) as the file name.

FORMAT FOR OPEN STATEMENTFORRANDOMACCESSDATA:

OPEN file#, device#, channel#, "#"
or optionally

OPEN file#, device#, channel#, "# buffer#"

EXAMPLES OF OPENING RANDOM ACCESS DATA CHANNEL:

OPEN 5, 8, 5, "#" DON'T CARE WHICH BUFFER

OPENA.B.C,"#~

BLOCK-READ

FORMAT FOR BLOCK-READ COMMAND:

PRINT# file#, "BLOCK-READ:" channel, drive, track, block

orabbreviatedas .

PRINT# file#, "B-R:" channel, drive, track, block

This command will move one block of data from the diskette into the

selected channel. Once this operation has been performed, the INPUT# and
GET# statements can read the information.

27

SAMPLE PROGRAM TO READ BLOCK 2 FROM TRACK 18: (stores contents

in B$)

10 OPEN 15,8,15

20 OPEN 5, 8,5,"#" ~

30PRINT# 15, "B.R:" 5,0, 18,2 ~

"" ~ ~ - LOCK

B$

40= ~

50 FOR L=OTO 255

-B

}

60 GET# 5, A$
70 IF ST=OTHEN B$=B$+A$: NEXT L
80 PRINT "FINISHED"
90 CLOSE 5: CLOSE 15

BLOCK-WRITE

COLLECT ENTIRE BLOCK,

BYTE BY BYTE

The BLOCK-WRITEcommand is the exact opposite of the BLOCK-READ

command. First you must fill up a data buffer with your information, then you
write that buffer to the correct location on the disk.

FORMAT FOR BLOCK-WRITE COMMAND:

PRINT# file#, "BLOCK-WRITE:" drive, channel, track, block

or abbreviated as

PRINT# file, "B-W:" drive, channel, track, block

When the data is being put into the buffer, a pointer in the DOS keeps
track of how many characters there are. Whenyou perform the BLOCK-WRITE
operation, that pointer is recorded on the disk. That is the reason for the ST
check in line 70 of the program above: the ST will become non-zero when you
try to read past the end-of-file marker within thr record.

SAMPLE PROGRAM TO WRITE DATA ON TRACK 1,SECTOR I:

10 OPEN 15,8, IS

20 OPEN 5, 8, 5, "#"

30FOR L=I to 50

40 PRINT#5, "TEST"

50 NEXT

60 PRINT# 15, "B-W:" 5,0, I, I

70 CLOSE 5: CLOSE 15

28

BLOCK.ALLOCAIE

In order to safely use random files along with regular files,your programs

must check the BAM to find available blocks, and change the BAMto reflect

that you've used them. Once you update the BAM,your random tiles will be
safe-at least unless you perform the VALIDATE command (see chapter 3).

FORMAT FOR THE BLOCK-ALLOCATE COMMAND:

PRINT# file#, "BLOCK.ALLOCATE:" drive, track, block

How do you know which blocks are available to use? If you try a block

that isn't available, the DOS will set the error message to number 65, NO

BLOCK, and set the track and block numbers to the next available track and
block number. Therefore, any time you attempt to write a block to the disk,
you must first try to allocate that block. If that block isn't available, read the

next block available from the error channel and then allocate that block.

EXAMPLE OF PROCEDURE TO ALLOCATE BLOCK:

10OPEN15.8,15

20 OPEN5,8,5, "# DRIVE

30PRINT#5,"DATA" / ~

40T=I:S=1 ~ ~

50 PRINT#15,"B-A:"0, T, S~

60 INPUT#15, A, B$, C, D

70 IF A=65 THENT=C: S=D: GOTO 50

80 PRINT# 15, "B.W:" 5,0, T, S

BLOCK-FREE

The BLOCK.FREE command is the opposite of BLOCK.ALLOCATE, in
that it frees a block that you don't want to use anymore for use by the system.
It is vaguely similar to the SCRATCH command for files, since it doesn't really

erase any data from the disk-just frees the entry, in this casejust in the BAM.

FORMAT FOR BLOCK.FREE COMMAND:

PRINT# f1le#, "BLOCK-FREE:" drive, track, block
or abbreviated as

PRINT# file#, "B.F:" drive, track, block

UsingRandom Files

The only problem with what you've learned about random fIles so far is

29

that you have no way of keeping track of which blocks on the disk you used.
After all, you can't tell one used block on the BAMfrom another. You can't tell

whether it contains your random file, just part of a program, or even sequential
or relative meso

To keep track, the most common method is to build up a sequential file to
go with each random file. Use this file to keep just a list of record, track, and
block locations. This means that there are 3 channels open to the disk for each

random me: one for the command channel, one for the random data, and the
other for the sequential data. This also means that there are 2 buffers that you're
fillingup at the same time!

SAMPLE PROGRAM WRITING 10 RANDOM-ACCESS BLOCKS WITH

SEQUENTIALFILE: .

10 OPEN 15,8,15
20 OPEN 5, 8, 5, "#
30 OPEN4,8,4, "@O:KEYS,S,W"
40 A$= "Record Contents #"

50 FOR R=l TO 10
70 PRINT# 5, A$ "," R

90 T=I: S=1

100 PRINT# 15, "B-A:" 0, T, S
110 INPUT# 15, A, B$, C, D
120 IF A=65 THEN T=C: S=D: GOTO 100
130 PRINT# 15, "B-W:" 5, 0, T, S
140 PRINT# 4, T "," S
150 NEXT R
160 CLOSE4: CLOSE 5: CLOSE 15

SAMPLE PROGRAM READING BACK 10 RANDOM-ACCESS BLOCKS WITH

SEQUENTIAL FILE:

10 OPEN 15,8,15
20 OPEN 5, 8, 5, "#"
30 OPEN4, 8, 4, "KEYS,S,R"

40 FOR R=1 TO 10
50 INPUT# 4, T, S

~

Finds Next Track
& Sector Used

60 PRINT# 15, "B-R:" 5, 0, T, S

30

80 INPUT# 5, A$, X
90 IF A$ < > "Record Contents #" OR X < > R THEN STOP

110 PRINT# 15, "B-F:" 0, T, S "'"
120 NEXT R

130 CLOSE4: CLOSE 5

Checks To Make

Sure Data Is OK

140 PRINT# IS, "S0:KEYS"
150 CLOSE 15

BUFFER-POINTER

The buffer pointer keeps track of where the last piece of data waswritten.
It also is the pointer for where the next piece of data is to be read. By changing
the buffer pointer's location within the buffer, you can get random access to the
individual bytes within a block. This way, you can subdivide each block into

records.

For example, let's take a hypothetical mailinglist. The information such as
name, address, etc., will take up a total of 64 characters maximum. We could
divide each block of the random access file into 4 separate records, and by
knowing the track, sector, and record numbers, we can access that individual

record.

FORMAT FOR BUFFER-POINTER COMMAND:

PRINT# file#, "BUFFER-POINTER:" channel, location

or abbreviated as

PRINT# file#, "B-P:" channel, location

EXAMPLE OF SETTINGPOINTER TO 64TH CHARACTER OF BUFFER:

PRINT# 15, "B-P:" 5, 64

Here are versions of the random access wwiting and reading programs

shown above, modified to work with records within blocks:

SAMPLE PROGRAM WRITING 10 RANDOM-ACCESSBLOCKS WITH 4

RECORDSEACH:

10OPEN

15,8,15

20 OPEN 5, 8, 5, "#
30 OPEN4, 8,4, "KEYS,S,W"

40 A$="Record Contents #"

50 FOR R=1TO 10
60 FORL=1 TO 4

31

70 PRINT# IS, "B-P:" 5: (L-I)'" 64 \. P~sitionto 0, 64, 128, or 192
80 PRINT# 5, AS "," L

90 NEXT L
100T=I: S=I
110 PR]NT# IS, "B-A:" 0; T; S
120 ]NPUT# IS, A, BS,C, D

s.

]30 IF A=65 THEN T=C: S=D: GOTO ] 10
140 PR]NT# IS, "B-W:" 5; 0; T; S
150 PRINT# 4, T "," S
160 NEXT R
170 CLOSE 4: CLOSE 5: CLOSE 15

SAMPLE PROGRAM READING BACK 10 RANDOM-ACCESS BLOCKS W]TH
4 RECORDS EACH:

10 OPEN IS, 8, 15
20 OPEN 5, 8, 5, "#
30 OPEN4, 8,4, "KEYS,S,R"
40 FOR R=I TO 10

50 ]NPUT#4, T, S
60 PRINT# ] 5, "B-R:" 5; 0;T; S
70 FOR L=1 TO 4

80 PR]NT# ]5, "B-P:" 5; (L-l)* 64

85 ]NPUT# 5, AS, X

90 IF AS< > "Record Contents #" OR X=L THEN STOP

100 NEXT L
110 PRINT# IS, "B-F:" 0; T; S

120 NEXT R
130 CLOSE4: CLOSE 5

140PRINT# 15, "SO:KEYS"

150 CLOSE 15

USERl and USER2

The user commands are generally designed to work with machine language

(see the next chapter for more on this). The USERI and USER2 commands are

special versions of the BLOCK-READand BLOCK-WRITEcommands, but. . .

32

with an important difference: the way USERl and USER2 work with the

buffer-pointer.

The BLOCK-READ command reads up to 256 characters, but stops

reading when the buffer-pointer stored with the block says that block is finished.

The USERI command performs the BLOCK-READoperation, but first forces

the pointer to 255 in order to read the entire block of data from the disk.

FORMAT FOR USERl COMMAND:

PRINT# file#, "VI :,. channel, drive, track, block

or

PRINT# file#, "VA;" channel, drive, track, block

There is no difference between the VI and VA designations for this

. command.

The BLOCK-WRITEcommand writes the contents of the buffer to the

block on the disk along with the value of the buffer-pointer. The USER2
command writes the buffer without disturbing the buffer-pointer value already

stored on that block of the diskette. This is useful when a block is to be read in
with BLOCK.READ, updated through the BUFFER-POINTER and PRINT#

statements, and then written back to the diskette with USER2.

FORMAT FOR VSER2 COMMAND:

PRINT# file#, "V2;" channel, drive, track, block

or

PRINT# file#, "VB:" channel, drive, track, block

For a more complex sample program, see appendix B.

7. RELATIVEFILES

Relative files allow you to easily zero in on exactly the piece of data that
you want from the file. It is more convenient for data handling because it allows
you to structure your filesinto records, and into fields within those records.

The DOS keeps track of the tracks and sectors used, and even allows

records to overlap from one block to the next. It is able to do this because it

establishes side sectors, a series of pointers for the beginning of each record.

Each side sector can point to up to 120 records, and there may be 6 side sectors

in a file. There can be up to 720 records in a file, and each record can be up to

254 characters, so the file could be as large as the entire diskette.

33

Creating a Relative File

When a relative file is first to be used, the OPEN statement will create that

file;after that, that samefile willbe used.The replaceoption (withthe@)sign)

does not erase and re-create the file. The file can be expanded, read, and written
into.

FORMATFORTHE OPENSTATEMENTTOCREATE RELATIVE FILE:

file#, device#, channel#, "name,L," + CHR$(record length)

OPEN

EXAMPLES OF OPEN STATEMENT CREATING RELATIVE FILES:

OPEN2, 8,2, "FILE,L,"+CHR$(lOO)

OPEN F, 8, F, A$+ ",L,"+ CHR$(Q)
OPEN A, B, C, "TEST,L,"+ CHR$(33)

Table 7.1 RELATIVE FILE FORMAT

DATA BLOCK

BYTE DEFINITION
0,1

2-256

Trackand

254 bytes of data. Empty records contain FF (all binary ones)
in the first byte followed by 00 (binary all zeros) to the end of
the record. Partially filled records are padded with nulls (00).

sectorof nextdatablock.

Record Length

SIDE SECTORBLOCK

BYTE DEFINITION
0,1

2
3

4,5
6,7 Track and sector of second side sector (number 1)
8,9
10,11 Track and sector of fourth side sector (number 3)
12,13 Track and sector of fifth side sector (number 4)
14,15
16-256

34

Trackand sector of next side sector block.

Side sector number. (0-5)

Record length.

Track and sector of first side sector (number 0)

Track and sector of third side sector (number 2)

Trackandsector of sicth side sector (number 5)
Trackand

sectorpointersto 120datablocks.

Upon execution,the DOSfirstchecksto see if the file exists.If it does,

then nothing happens. The only way to erase an old relative file is by usingthe

SCRATCHcommand (see chapter 4), but not by using the replace option.
UsingRelative Files

In order to OPEN a relative fileonce it exists, the format is simpler.

FORMAT FOR OPENING AN EXISTING RELATIVE FILE:

OPEN file#, device#, channel#, "name"

In this case, the DOS automatically knows that it is a relative file. This
syntax, and the one shown in the above section, both allow either reading or
writing to the file.

In order to read or write, you must, before any operation, position the file
pointer to the correct record position.

FORMAT FOR POSITION COMMAND:

PRINT# file#, "P" CHRS(channel#) CHR$(rec# 10)CHR$(rec# hi)

or optionally as

PRlNT#file#, "P" CHR$(channel#) CHR$(rec#lo) CHR$(rec#hi) CHR$(position)

EXAMPLES OF POSITION COMMAND:

PRINT# IS, "P" CHR$(2

PRINT# 15, "P" CHR$(CH) CHR$(Rl) CHR$(R2)

CHR$(I) CHR$(O)

~

~

PRINT# 15, "P" CHR$(4) CHR$(R{fCHR$(R2) ~R$(P)

The 2.byte format for the record number is needed because one byte can
only hold 256 different numbers, and we can have over 700 records in the file.
The rec# 10contains the least significant part of the address, and the rec# hi is
the most significant part. This could be translated to the actual record number
by the"formula REC#= REC HI * 256 + REC LO.

Let's assume we have a mailing list. The list consists of 8 pieces of data,
according to this chart:

Field Name

first name

last name

address line 1

address line 2

city

Length

12

15
20
20

12

state 2
zip code 9

phone number 10

----------

TOTAL 100

35

This is how the record lel1gth is determined. We would probably want to

allow an extra character in length for each field, to allow for separations;

otherwise the INPUT# command would pick up a much longerpiece of the file
than needed, just like in sequential files. Therefore, we'll set up a file with a
length of 108 characters per record. In the first record, we'll put the number 1,
representing the largest record# used so far. Here isthe program as described so

far:

10 OPEN I, 8, 15

20 OPEN 2, 8, 3, "O:MAILINGLlST,L,"+CHR$(108)
30 GOSUB900

40 PRINT# I, "p" CHR$(3) (CHR$(l) CHR$(O)CHRS(l)

50 GOSUB900

60 IF E=50 THEN PRINT#2, I: GOTO 40
70 INPUT# 2, X

300 STOP
900 INPUT# I, E, B$, C, D
910 IF (E=50) OR(E < 20) THEN RETURN

920 PRINT A; B;C; D: STOP: RETURN

Error #50 which is checked in line 60 of the program is the RECORD

NOT PRESENT error, which means that the record hadn't been created yet.
Writing into the record will solve the proglem. This error condition must be
watched carefully within your programs.

So far, all it does is create the file and the first record, but doesn't actually
put any data in it. Below is a greatly expanded version of the program, to

actually allow you to work with a mailing list where the records are coded by
numbers.

MAILING LIST READ AND WRITE PROGRAM:

5 A(I) =12:A(2) =15:A(3) =20:A(4) =20:A(5) = 12:A(6) =2:A(7) =9:A(8) =10

10 OPENI,8,15:0PEN2,8.3,"0:Mailing List,l ,"+CHRS(108):GOSUB900
20 PRINT#I ,"p"CHRS(3)CHRS(I) CHRS(O) CHRS(1 ):INPUT#2,X
30 INPUT'Read, Writ., or End..JS:IFJS= THENCLOSE2:CLOSEI:END
40 IFJS="w"THEN200
50 PRINT:INPUT"R.cord #":R:IFR<00RR>XTHEN50
60 IFR<2THEN30
70 RI=R:R2=0:IFRI > 256THENR2=INT(RI/256):RI=RI.256°R2
80 RESTORE:DA TI,FI RST NAME,14,LAST NAME,30,ADDRESSI ,51,ADDRESS2
90 DATA72,CITY ,85,5T ATE.88.ZIP.98.PHONE#

100 FORL=I T08:READA,AS:PRlNT#1 ,"p"CHRS(IJ) CHRS(RI) CHRS(R2) CHRS(A):GOSUB900

110 ONA/50GOT050:INPUT#2,ZS:PRlNTAS,ZS:NEXT:GOT050
200 PRlNT:INPUT'R.cord #":R:IFR<OORR>5000TlIEN200
210 IFR<2THEN30
215 IFR> XTHENR=X+ I:PRINT:PRINT"Record# "R

220 RI=R:R2=0:IFRI >256THENR2=INT(RI/256) :RI=RI
230 RESTORE: FORL= 1T08: READA,AS:PRlNT#I, "p"CHRS(3) CHRS(RI) CHRS(R2) CHRS(A)
240 PRINTA$,:INPUTZ$:IFLEN(ZS) > A(L)THENZS=LEFT$(ZS.A(L»
245 PRlNT#2,ZS:NEXT:X=R:PRINT#1 ,"p"CHRS(3) CHRS(I) CHRS(O)
250 PRlNT#2,X:GOT0200
900 INPUT#I ,A,BS,C.D:IF A< 20THENRETURN
910 IFA < > 50THENPRINT A:BS,C;D:STOP: RETURN

920 IFJS="r"THENPRINTBS
930 RETURN

36

- 256°R2

" ..

This program asks for record numbers when retrieving records. It won't let

you retrieve from beyond the end of the file, and if you try to write beyond the

end it forces you to write on the next higher record.

A more advanced version than this would keep track of the items by
"keys", to index the records. For example, you would probably want to search
for a record by name, or print out labels by zip code. For this you would need a
separate list of keys and record numbers, probably stored in sequential files.

When working with a new relative file that will soon be very large, it will
save much time to create a record at the projected end of the file. In other
words, if you expect the file to be 1000 records long, create a record# 1000 as

soon as the file is created. This will force the DOS to create all intermediate
records, making later use of those records much faster.

EXAMPLEOF CREATING LARGE FILE:

OPEN 1,8, IS: OPEN 2, 8, 2, "REL,L,"+ CHR$(60)

PRINT# I, "P" CHR$(2) CHR$(O)CHR$(4) CHR$(I)

PRINT# 2, "END"

CLOSE 2: CLOSE I

8. PROGRAMMING THE DISK CONTROLLER

The expert programmer can actually design routines that reside and
operate on the disk controller. DOS routines can be added that come from the
diskette. Routines can be added much the same way as the DOS Support
Program is "wedged" into your memory.

BLOCK.EXECUTE

This command will load a block from the diskette containing a machine
language routine, and begin executing it at location 0 in the buffer until aRTS
(ReTurn from Subroutine) command is encountered.

FORMAT FOR BLOCK-EXECUTE:

PRINT# file#, "BLOCK-EXECUTE:" channel, drive, track, block

or abbreviated as

PRINT# file#, "BLOCK-EXECUTE:" channel, drive, track, block

MEMORY.READ

There is 16K of ROM in the disk drive as well as 2K of RAM.You can get
direct access to these, or to the buffers that the DOShas set up in the RAM,by
using the MEMORY commands. MEMORY-READ allows you to select which
byte to read, through the error channel.

37

FORMATFORMEMORY-READ:

PRINT# file#, "M-R:" CHR$(low byte of address) CHR$(highbyte)

(no abbreviation!)

The next byte read using the GET# statement through channel# IS, the
error channel, will be from that address in the disk controller's memory, and
successivebytes will be from successivememory locations.

Any INPUT# to the error channel will give peculiar results when you're
using this command. This can be cleared up by any other command to the disk
(besides a memory command).

PROGRAM TO READ THE DISK CONTROLLER'S MEMORY:

10OPEN15,8,15

20 INPUT"LOCATION PLEASE"; A
30 AI= INT(A/2S6): A2= A- Al *256

40 PRINT# IS, "M-R:" CHR$(A2) CHR$(AI)

SOFOR L=I TO 5
60 GET# IS, A$

70 PRINT ASC(A$+CHR$(O));

80 NEXT
90 INPUT "CONTINUE";A$

100 IF LEFT$(A$,I) ="Y" THEN SO

110 GOTO20

MEMORY-WRITE

The MEMORY-WRITEcommandallowsyou to write up to 34 bytesat a
time into the disk controller's memory. The MEMORY-EXECUTEand USER
commands can be used to run this code.

FORMAT FOR MEMORY-WRITE:

PRINT# file#, "M-W:" CHR$(low address byte) CHR$(high address byte)

#-of-characters; byte data

PROGRAM TO WRITE A "RTS" TO DISK:

I0 OPENIS, 8, IS. "M-W:" CHR$(O)CHR$(S); I; CHR$(96)

20 PRINT# IS, "M-E:" CHR$(O)CHR$(I 9): REMJUMPSTO BYTE,RETURNS

30 CLOSE IS -

MEMORY-EXECUTE

Any routine in the DOSmemory, RAMor ROM, can be executed with the

MEMORY-EXECUTEcommand.

38

FORMAT FOR MEMORY-EXECUTE:

PRINT#

file#, "M-E:" CHR$(1ow address byte) CHR$(high byte)

Seeline 20 above for an example.

USER Commands

Aside from the USERI and USER2 commands discussed in chapter 6, and
the UI+ and UI- commands in chapter 2, the USER commands are jumps to a
table of locations in the disk drive's RAMmemory.

USER COMMAND

UI or UA

U2 or UB
03 or UC
U4 or UD
US or UE
U6 or UF
U7 or UC
U8 or UH

U9 or VI

U; or UJ
VI+
VI-

BLOCK-READwithout changing buffer-pointer

BLOCK-WRITEwithout changing buffer-pointer
jump to $0500
jump to $0503
jump to $0506
jump to $0509
jump to $050C

jump to $050F
jump to $FFF A

power-up vector

set Commodore 64 speed

set VIC 20 speed

FUNCTION

Byloadingtheselocationswith anotherjump command,likeJMP$0520,

you can create longer routines that operate in the disk's memory alongwith an
easy-to-usejump table-even from BASIC!

EXAMPLES OF USER COMMAMDS:

PRINT# 15,"03"

PRINT# 15, "U"+ CHR$(50+Q)

PRINT# 15, "VI"

9. CHANGING THE DISK DRIVE DEVICE NUMBER

Software Method

The devicenumber is selectedby the drive by

jumper on the board and writing the number based on that jumper in a section
of its RAM. Once operation is underway, it is easy to write over the previous

device number with a new one.

FORMAT FOR CHANGING DEVICE NUMBER:

looking at a hardware

39

PRlNT# file#, "M-W:" CHR$(119) CHR$(O)CHR$(2) CHR$(address+32)

CHR$(address+64)

EXAMPLE OF CHANGING DEVICE NUMBER:

PRINT# 15, "M-W:" CHR$(l19) CHR$(O)CHR$(2) CHR$(9+32) CHR$(9+64)
PRlNT# Q, "M-W:" CHR$(119) CHR$(O)CHR$(2) CHR$(R+32) CHR$(R+64)

If you have more than one drive, it's sensible to change the address
through hardware (see below). If you must, the procedure is easy. Just plug in
the drives one at a time, and change their numbers to the desired new values.
That way you won't have any conflicts.

Hardware Method

It's an easy job to permanently change the device number of your drive for
use in multiple drive systems. The tools needed is a phillips-head screwdriverand

a knife.

STEPS TO CHANGING DEVICE NUMBER ON HARDWARE:

1. Disconnect all cablesfrom drive, including power.

2. Turn drive upside down on a flat, steady surface.

3. Remove 4 screwsholding drive box together.

4. Carefully tum drive right sideup, and remove case top.
S. Remove 2 screwson side of metal housing.

6. Remove housing.

7. Locate device number jumpers. If facing the front of the drive, it's

on the left edge in the middle of the board.

8. Cut either or both of jumpers 1 and 2.

9. Replace housing and 2screws, and case top and 4 screws.

10. Re-connect cables and power up.

The jumper number is added to the old device number (8) when cut. In
other words, jumper 1 adds 1, and jumper 2 adds 2, to the device number. If
none are cut, the number is 8, if 1 iscut it goes up to 9, and if only 2 is cut the
number is 10. If both I and 2 are cut, the number is 11.

40

Appendix A: Disk Command Summary

General Format: PRINT# file#, command

COMMAND

NEW
COpy
NAME
SCRATCH
INITIALIZE
VALIDA TE
DUPLICATE
BLOCK-READ
BLOCK-WRITE
BLOCK-ALLOCATE
BLOCK-FREE
BUFFER-POINTER
USERl. and USER2

POSITION

BLOCK.EXECUTE
MEMORY-READ
MEMORY-WRITE

MEMORY-EXECUTE
USER Commands

COMMAND FORMAT

"N
"CO:new file=O:originalfile

"RO:new name=O:oldname
"SO:filename
"I
"V

not for singledrives
"B-R:" channel; drive; track; block
"B-W:" channel; drive;track; block

"B-A:" drive; track; block
"B-F:" drive; track; block

"B.P:" channel; position
"Un:" channel; drive; track; block
"P" CHR$(channel#) CHR$(rec# 10)CHR$(rec# hi)

CHR$(position)
"B-E:" channel; drive; track; block
"M-R:" CHR$(address 10)CHR$(address hi)
"M-W:" CHR$(address 10)CHR$(address hi) CHR$
(# chars) "data"

"M-E:" CHR$(address 10)CHR$(address hi)
"Un:"

41

Appendix B: Summaryof CBMFloppy ErrorMessages

o

I

2-19

20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
39
50
51
52
60
61
62
63
64
65
66
67
70
71
72
73
74

OK, no error exists.
Files scratched response. Not an error condition.
Unused error messages:should be ignored.

Blockheader not found on disk.

Sync character not found.

Data block not present.
Checksum error in data.

Byte decoding error.
Write-verifyerror.
Attempt to write with write protect on.
Checksum error in header.
Data extends into next block.
Disk id mismatch.

General syntax error.
Invalid command.

Long line.
Invalid filename.

No filegiven.

Command me not found.

Record not present.
Overflowin record.

File too large.
File open for write.
File not open.

File not found.
File exists.
File type mismatch.

No block.
Illegaltrack or sector.

Illegalsystem track or sector.
No channels available.

Directory error.
Disk full or directory full.

Power up message,or write attempt with DOSMismatch.

Drivenot ready. (8050 only)

42

DESCRIPTIONOF DOSERROR MESSAGES

NOTE: Error message numbers less than 20 ~hould be ignored with the
exception of 01 which gives information about the number of files scratched

with the SCRATCHcommand.

20: READ ERROR (block header not found)

The disk controller is unable to locate the header of the requested data

block. Caused by an illegal sector number, or the header has been

destroyed.

21: READ ERROR (no sync character)

The disk controller is unable to detect a sync mark on the desired track.
Caused by misalignment of the read/write head, no diskette ispresent, or
unformatted or improperly seated diskette. Can also indicate a hardware

failure.

22: READ ERROR (data block not present)

The disk controller has been requested to read or verify a data block that
was not properly written. This error message occurs in conjunction with
the BLOCK commands and indicates an illegaltrack and/or sector request.

23: READ ERROR (checksum error in data block)

This error message indicates that there is an error in one or more of the
data bytes. The data has been read into the DOS memory, but the
checksum over the data is in error. This message may also indicate
grounding problems.

24: READ ERROR (byte decoding error)

The data or header has been read into the DOS memory, but a hardware
error has been created due to an invalid bit pattern in the data byte. This
messagemay also indicate grounding problems.

25: WRITE ERROR (write-verify error)

This message is generated if the controller detects a mismatch between the
written data and the data in the DOSmemory.

26: WRITE PROTECTON

This message is generated when the controller has been requested to write

a data block while the write protect switch is depressed. Typically, this is

caused by usinga diskette with a write protect tab over the notch.

27: READ ERROR (checksum error in header)

The controller has detected an error in the header of the requested data
block. The block has not been read into the DOS memory. This message

may also indicate grounding problems.

43

28: WRITE ERROR (long data block)

The controller attempts to detect the sync mark of the next header after
writing a data block. If the sync mark does not appear within a
pre-determined time, the error message is generated. The error is caused by
a bad diskette format (the data extends into the next block), or by

hardware failure.

29: DISK ID MISMATCH

This message is generated when the controller has been requested to access
a diskette which has not been initialized. The message can also occur if a

diskette has a bad header.

30: SYNTAX ERROR (general syntax)

The DOS cannot interpret the command sent to the command channel.
Typically, this is caused by an illegalnumber of file names, or patterns are
illegally used. For example, two file names may appear on the left side of

the COPYcommand.

31: SYNTAX ERROR (invalid command)

The DOS does not recognize the command. The command must start in
the first position.

32: SYNTAXERROR (longline)

The command sent islonger than 58 characters.

33: SYNTAX ERROR (invalid file name)

Pattern matching is invalidly used in the OPEN or SAVEcommand.

34: SYNTAX ERROR (no file given)

The file name was left out of a command or the DOS does not recognize it
as such. Typically, a colon (:) has been left out of the command.

39: SYNTAXERROR (invalidcommand)

This error may result if the command sent to command channel
(secondary address IS) is unrecognizable by the DOS.

50: RECORDNOT PRESENT

Result of disk reading past the last record through INPUT#, or GET#
commands. This message will also occur after positioning to a record
beyond end of file in a relative file. If the intent is to expand the file by
adding the new record (with a PRlNT# command), the error messagemay
be ignored. INPUT or GET should not be attempted after this error is

detected without first repositioning.

51: OVERFLOWIN RECORD

PRINT# statement exceeds record boundary. hiformation is truncated.
Since the carriage return which issent as a record terminator is counted in

the record size, this messagewill occur if the total characters in the record
(including the final carriage return) exceeds the defined size.

44

FILE TOO LARGE

52:

Record position within a relative file indicates that disk overflow will
result.

60: WRITE FILE OPEN

This message is generated when a write file that has not been closed is
being opened for reading.

61:

FILE NOT OPEN

This message is generated when a file is being accessed that has not been

opened in the DOS. Sometimes, in this case, a message is not generated;
the request is simply ignored.

'").

FILE NOT FOUND

..

6

The requested file does not exist on the indicated drive.

63:

FILE EXISTS
The file name of the file beingcreated already exists on the diskette.

64:

FILE TYPE MISMATCH
The file type does not match the file type in the directory entry for the

requested file.

65:

NO BLOCK
This message occurs in conju»ction with the B-Acommand. It indicates
that the block to be allocated has been previously allocated. The
parameters indicate the track and sector available with the next highest
number. If the parameters are zero (0), then all blocks higher in number

are in use.

66:

ILLEGAL TRACK AND SECTOR
The DOS has attempted to access a track or sector which does not exist in

the format being used. This may indicate a problem reading the pointer to
the next block.

ILLEGAL SYSTEM T OR S

67:

This special error message indicates an illegal system track or sector.

70:

NO CHANNEL(available)
The requested channel is not available, or all channels are in use. A
maximum of five sequential files may be opened at one time to the DOS.

Direct accesschannels may have six opened files.

71: DIRECTORY ERROR

The BAM does not match the internal count. There is a problem in the

BAM allocation or the BAMhas been overwritten in DOS memory. To

correct this problem, reinitialize the diskette to restore the BAM in

memory. Some active files may be terminated by the corrective action.

NOTE: BAM =Block Availability Map

I

45

72: DISK FULL

Either the blocks on the diskette are used or the directory is at its limit of
152 entries for the 2040, 3040, and 4040 or 243 entries for the 8050.

DISK FULL is sent when two blocks are available on the 8050 to allow
the current me to be closed.

73: DOSMISMATCH(73, CBMDOS V2.5 8050)

(73, CBMDOS V2) for 4040

DOS I and 2 are read compatible but not write compatible. Disks may be
interchangeably read with either DOS, but a disk formatted on one version
cannot be written upon with the other version because the format is
different. This error is displayed whenever an attempt is made to write
upon a disk which has been formatted in a non-compatible format. (A
utility routine is available to assist in converting from one format to
another.) This messagemay also appear after power up.

74: DRIVE NOT READY

An attempt has been made to access the 8050 Dual Drive Floppy Disk
without any diskettes present in either drive.

46

APPENDIX C: Demonstration Disk Programs

1. D/R

4 OPEN2.. 8,15
5 PRINT":1":GOTO 1121121121121

1101OPENL8..e, "$101"
2121 GETlll,A$,B$
313 GETIIL A$, B$
413 GETIIL A$, B$
5101 C=!!I
60 IF A$()"" THEN C=ASC(A$)
713 IF B$()"" THEN C=C+ASC(B$)i!!256
8101 PRINT" ~"MID$(STR$(C), 2); TAB(3); "~";
913 GETlll,B$:IF ST(>e THEN 11211313

lee IF B$(>CHR$(34) THEN 9121

11121 GETlll,B$:IF B$(>CHR$(34)THEN PRINTB$; : GOT011121
12121 GETlll,B$:IF B$=CHR$(32) THEN 12121
13121 PRINT TAB<l8); : C$=""

14121C$=C$+B$:GETlIl,B$: IF B$(>"" THEN 14121

15121 PRINT"~"LEFT$(C$,3)
16121 GET T$: IF T$O"" THEN GOSUB 21210121
17121 IF ST~12I THEN 3121
1121121121PRINT" BLOCKS FREE"

11211121 CLOSE1:GOTO 1121121121121

213121121IF T$="Q" THEN.CLOSE1:END
21211121GET T$: IF T$="" THEN 212113121

2132121 RETURN
413121121REM DISK COMMAND
4131121 C$="":PRINT")";
412111 GETB$: I FB$="" THEN412111
412112 PRINTB$; :IF B$=CHR$(13) THEN 41212121
412113 C$=C$+B$:OOTO 412111
41212121PRHITII2, C$
5121121121PRINT"~".:

51211121GETII2,A$:PRINTA$; :IF A$(>CHR$(13)GOT051211121
51212121PRINT"~"

11211210121PRINT "D-DIRECTOR'T"
11211211121PRINT ")-DISK COMMAND"
10020 PRINT "Q-QUIT PROGRAM"
101213121PRINT "S-DISK STATUS "
11211121121GETA$:IFA$=""THENl1211121121
102121121IF A$="D" THEN 1121
112131210IF A$="." OR A$=")" OR A$=">" THEN 4121121121

112131121IF A$="Q" THEN END
112132121IF A$="S" THEN 5121121121
1121999 GOTO 11211121121

2. VIEW SAM

1121121REM ************.*.*.*..*.*...

10.1 REM. VI~W BAM FOR VIC & 64 DISK *

102 REM ,..........................

1121:5OPEN15,S,15
11121 PRINTII15,"II2I":NU$="N/A N/A N/A N/A N/A":Z4=1

12121 OPEN2,S,2,"II"
13121 'T$~" j:!)roll)lnal!lwt~tljl)jll~l)q'a.aIQ)'OO)II~J"

14121 X$=" "
15121 DEF FNS(Z) = 2f(S-INT(S/S)i!!S) AND (SB(INT(S/S»)

47

1613 PRINTiI5."Ul:";2;0;18;a

17121 PRINTiI5."B-P";2;1

18121PRINT":'1";

19121 ¥=22:X=I:GOSUB43a

2130 FORI=0T020:PRINT:PRINT":T1"RIGHT$(STR$(I>+" ".3); :NEXT
21121GET#2,A$
220 GEHI2. A$
23121GET#2., A$
240 TS=0

25121FORT=lTOI7:GOSUB450
26121Y=22:X=T+4:GOSUB43e:GOSUB54a:NEXT
270 FORI=lT02a0a:NEXT:PRINT":'1"
28121Y=22:X=I:GOSUB430

29121FORI"0T02a: PRUIT: PRINT":T1"RIGHT$(STR$( I)+" ".3);: NEXT
31210FORT=18T035

31121 GOSUB450

32121Y=22:X=T-13:GOSUB43a:GOSUB~4a:NEXT
330 FORI=lT0100a:NEXT

34121PRINT"~"
350 PRIt~T#15. "B-P"; 2; 144
36121N$="":FORI=IT020:GET#2,A$:N$=N$+A$:NEXT
37121PRINT" "N$" "TS-17;"BLOCKS FREE"
38121FORI=IT04aaa:NEXT
3913 PRUIT":,]"
400 INPUT" J.MdIJFI~IOTHER DISKETTE t~I..I".: A$

410 IFA$="Y"THENRUN
42121IFA$O"¥"THENEND
43121PRINTLEFT$(Y$. Y)LEFT$(X$. >0 "II";
44121RETURH
45121GET#2.SC$:SC=ASC(RIGHT$(CHR$(0)+SC$.1»

460 TS=TS+SC
47121GET#2.A$:IFA$=""THENA$=CHR$(0)
480 SB(0)=ASC(A$)
4913 GET#2,A$:IFA$=""THENA$=CHR$(a)
51210SB(I)=ASC(A$)
51121GET#2., A$: I FA$= '''' THEHA$=CHR$ (.,)
52121SB(2)=ASC(A$)

530 RETUR~I
54121PRIHT"QI"RIGHT$(STR$(T). 1); "1m";
55121REM PRUITT" "SC" "SB(a)" "SB( 1)" "SB(2)=CHR$(e)
56121IFT>24AHDS=18THEH:PRINTMID$(NU$.Z4,1); :GOT066121
5713 FORS=0T020
58121IFT<18THEN62121
590 IFT>30AHDS=17THEN:PRINTMID$(NU$.Z4.1); :GOT066e
6121121IFT)24AHDS=18THEN:PRINTMID$(NU$.Z4.1);
61121IFT)24AHDS=19THENPRINTMID$(NU$,Z4.1); :GOT066a
6213 IFT>17AHDS=2aTHENPRINTMID$(NU$,Z4.1);

6313 PRIt~T" ::I".:
64121I F F~IS(S) =121THEN PR HIT" +".: :GOT066a
6513 PRIt~T"!!!+".: :REt1RIGHT$(STR$(S). 1); 24.1).: : GOT072

6613 PRU~T""I!!!";
6713 NEXT

6813 RETUR~I

:GOT066e

:24=24+1:GOT066a

48

3. DISPLAYT& S

lee REM"'''''..'*' ' *-.

lIe REt1'" DISPLA'T' A~JY TRACK $ SECTOR '"
1213 REM. ON THE DISK TO THE SCREEN .
1313 REM. OR THE PRINTER *-
1413 REM"'''''''''''''''''''''''''''''''''''''''''''*'''''''''*'''**'''''''''''''''..
1513 PRHH":'IIIiIIl
1613 PRHIT"DISPLA'T' BLOCK COtnENTS"
165 PRINT" ":

1713REM * "''''.'''.'''.........

1813 REM'" SET PROORAMCONSTANT ...

1913REM..".'."".." "'......_._.

21313SP$=" ": NL$=CHR$(e) :H7~$="eI23456789ABCDEF"
2113 FS$="":FORI=64 TO 95:FS$=FS$+"~"+CHR$(I)+"!!":NEXT I
2213 SS$=" ":FOR 1=192 TO 223:SS$=SS$+"~"+CHR$(I)+"!!":NEXT
2413

DIMA$(15),NB(2)

251 D$="0"
253 PRINT" ~!!!J;REENQ.DI..II.8)R QI:P!!RINTER"
254 GETJJ$: IF JJ$="" THEN254
255 IF JJ$="S"THE~IPRHIT"
256 IF JJ$="P"THENPRINT"
2613 OPEN15.8.15."I"+D$:GOSUB
265 OPEN4.4
2713 OPEN 2,8,2, "#":OOSUB 650
2813 REM."' ",,,,...*...,,, *,,,,,,.,,,***,,,
2913 REM'" LOAD TRACK AND SECTOR *
31313REM... INTO DISK BUFFER .

3113 REt1"'.************"'** *............

3213 INPUT" :ODITRACK, SECTOR".: T.'S

3313 IF T=e OR T>35 THEN PRINT#15."I"D$:CLOSE2:CLOSE4:CLOSE15:PRINT"END":E~1D
3413 IF JJ$="S" THEN PRINT":ODITRACK"T" SECTOR"S")1"
341 IF JJ$="P" THEN PRINT#4:PRINT#4."TRACK"T" SECTOR"S:PRINT#4
3513 PRINT#15."Ul:2,"D$;T;S:GOSUB650

3613 REM *** ** "' * *............

3713 REM. READ BYTE 13 OF DISK BUFFER ...

3913 REM................................................

4013 PRINT#15,"B-P:2,1"
4113 PRINT#15, "M-R"CHR$(e)CHR$(5)
4213 GET#15,A$(e):IFA$(e)=""THENA$(e)=NL$
428 IF JJ$="S"THEN43e
4313 IF JJ$="P"THE~146e

431 REM "'...** "'''''''*******''' * '''

432 REM* READ & CRT DISPLAY ...

433 REM'"REST OF THE DISK BUFFER ...

434 REM................................................................

436 K=l:NB(l)=ASC(A$(13»
438 FOR J=e TO 63: IF J=32 THEN GOSUB 7H): IF Z$="N"THEN J=80:00TO 458

4413 FOR I=K TO 3
442 GET#2, A$( 1) : IF A$( 1)='''' THEN A$( 1)=t.jL$
444 IF K=l AND 1(2 THEN NB(2)=ASC(A$(I»
446 NEXT I: K=0
448 A$="":B$=":":N-J.4:00SUB 7ge:A$=A$+":"
4~e FOR 1=0 TO 3:N=ASC(A$(I»:GOSUB 790
452 C$=A$(I):GOSUB 8513:B$=B$+C$
454 NEXT I:IF JJ$="S" THEN PRINTA$B$
458 NEXT J:GOT0571

)1~CREEN!!"
)1:PRINTER!!"

6513

49

4613 REM******************************

462 REM* READ & PRINTER DISPLAY *

464 REM********************_**_******

466 K~l:NB(l)=A$C(A$(e»

468 FOR J=0 TO 15

4713 FOR I=K TO 15

472 GETII2, A$<I): IF A$( I)="" THEN A$( I)=NL$

474 IF K=l AND 1<2 THEN NB(2)=ASC(A$(I»

476 NEXT I: K=0

476 A$="":B$=":":N=J*16:GOSUB 790:A$=A$+":"

4813 FOR I-a TO 15:N=ASC(A$(I»:GOSUB 7913: IF Z$="N"THEN J=4e:00TO 571

462 C$=A$(I):GOSUB sse:B$=B$+C$

4S4 NEXT I

486 IF JJ$="P" THEN PRINT#4,A$B$

488 NEXT J:00T0571

571

REM*_****_*_*********************

572 REM* NEXT TRACK AND SECTOR

573 REM*_***_**_*****_***************

575 PRINT"NEXT TRACK AND SECTOR"NB(1)NB(2) "II"

560 PRINT"DO YOU WANT NEXT TRACK AND SECTOR"

5913 GET 2$:IF 2$="" THEN598

6013 IF 2$="Y" THEN T=NB(1):S=NB(2):GOT0330
6113 IF 2$="N" THEN 3213

6213 OOTO 5913

6313REM********************_*********
6413REM* SUBROUTINES _

6513 REM******__****_**************__*

6613REM* ERROR ROUTINE *

6713 REM***_**************************

6813 INPUTII15,EN,EM$,ET,ES:IF EN=0 THEN RETURN
690 PRINT"=rDISK ERROR!!!"EN,EM$,ET,ES

7013 END

7113REM****************************_*
7213REM* SCREEN CONTINUE MESSAOE

7313 REM_*_***_*_*****************__*_
7413 PRINT" CONTINUE(Yt'N)"

7513 OET2$:IF Z$="" THEN 750

7613 IF 2$="N" THEN RETURN

7713 IF

7813 PRINT":'1TRACK" T " SECTOR"S ":']":RETURN
7913 REM*_****_*************__*_***.._
81313REM_ DISK BYTE TO HEX PRINT _
8113 REM*********.**.*****************

8213 Al=INT(Nt'16):A$=A$+MID$(HX$,Al+l,1)
8313 A2=INT(N-16*A1):A$=A$+MID$(HX$,A2+1,1)
8413 A$=A$+SP$:RETURN
8513 REM******************************

8613 REM* DISK BYTE TO ASC DISPLAY *

6713REM* CHARACTER *

sse REM******************************

89121 IF ASC(C$)<:32 THEN C$=" ":RETURN
9113 IF

920 C$=MID$(SS$,3*(ASC(C$)-127),:3):RETURN

2$O"Y" THEN 7513

ASC(C$)(128 OR ASC(C$»159 THEN RETURN

_

_

50

4. CHECK DISK

1 REM CHECK DISK -- VER 1.4
2 DN=8:REM FLOPP~ DEVICE NUMBER
5 DIMT(laa):DIMS(laa):REM BAD TRACK, SECTOR ARRA~
51 PRINT":'MWOO

113 PRINT" CHECK DISK PROGRAM"

12 PRINT"

213 D$="a"

313 OPEN15,DN,15

PRHITII15,"V"D$

35

45 N~=RND(TI)*255

513 A$= ''"':FOR I= 1T0255 :A$=A$+CHR$ (255AND (1 +Nr.» :NEXT

6a GOSUBSlaa

713 OPEN2,DN,2, "II"

813 PRINT:PRINT#2,A$;

85 T=l: 5=13

913 PRINTII15, "B-A: "D$; T.:$

11313INPUTII15,EN,EM$,ET,ES

1113 IFEN=aTHEN13a

115 IFET=aTHEN2aa:REM END

1213 PRINTII15, "B-A: "D$.:ET; ES: T=ET: S=ES

1313 PRINTII15."U2:2,"D$;T;$
134 NB=NB+l:PRINT" CHECKED BLOCKS"NB

135 PRINT" TRACK IIIII"T;" SECTOR 11111"S ":11"

1413 INPUT#15.EN,EM$.ES,ET
150 IF EN=0THEN85

1613 T(J)=T:S(J)=S:J=J+l
165 PRINT"~AD BLOCK: III",T; 5''"'

1713 GOT085
21313PRINTII15,"I"D$
2113 G05UBSla13

212 CLOSE2
215 IFJ=aTHENPRINT"mlD..tlO BAD BLOCKS!":END
2170PEN2.DN,2."#"
218 PRINT"~AD BLOCKS","TRACK","SECTOR"
2213 FORI=aTOJ-l
2313 PRINTII15,"B-A:";D$,T(I);S(I)

2413PRINT"T(I>.S(I) .

2513 NEXT

2613 PRINT":.I"J"BAD BLOCKS HAVE BEEN ALLOCATED"

2713 CLOSE2:END
511313INPUT#15.EN,EM$,ET,ES

9113 IF EN=a THEN RETURN

$1213PRINT":.lERROR !!"EN,EI1$;ET; E5''"'
9313 PRINTII15,"I"D$

"

5. PERFORMANCE TEST

1131313REM PERFORMANCE TEST 2.13
113113
113213REM VIC-2a AND COMMODORE 64
113313REM SINGLE FLOPP~ DISK DRIVE
113413
113513OPEN 1,S,15:0PEN15,S,15
113613LT=35
113713LT$=STR$(LT>

51

1"'81:1 NT=30

\1390 !>!>.IN,'':N

~~1%~~i~~':, ?ERFQR\~~HCE ,I::S,"

1121:1 PRINT

1131:1 PRINT" INSERT SCRATCH"

1.1413 PRINT

1150 PRINT" DISKETTE IN DRIVE"

11613PRINT

11713 PRHIT"~ PRESS ~ETURN!!!"
1180 PRINT
1Ige PRINT" WHEN READ'r'JII"
1200 FOR 1=0 TO 50:GET A$:NEXT
12110 GET A$:IF A$()CHR$(13) THEN 1210

'220
1230

1240 TI $=" 000000"
1250 TT=18
1260 PRINT#I, "N0:TEST DISK,e0"
12713 Cl$=" DISK NEW COMMAND "+CHR$( 13)
1280 C2$="JII WAIT ABOUT 80 SECONDS"
1290 CC$=Cl$+C2$:GOSUB 1840
131313

IF TI(NTTHENI37e

13113 PRINT"~'r'STEM IS"
1320 PRINT"~ NOT RESPONDING"

13313 PRH~T" CORRECTL'r' TO COMMANDS"

13410 GOSUB 18813

1358

13613
13713 PRINT":.IDRIVE PASS"
13813 PRINT" MECHANICAL TESTJII"
13913 TT=21
141313OPEN 2.8,2, "0:TEST FILE,S,W"
1410 CC$="OPEN WRITE FILE" :GOSUB 18413

1.420 CH=2:CC$="WRITE DATA" :GOSUB 19313
1430 CC$="CLOSE "+CC$ : GOSUB 18413
14413 OPEN 2.8,2, "13: TEST FILE,S,R"
14513 CC$="OPEN READ FILE" :GOSUB 1840
1460 CH=2:GOSUB 1990
1470 PRINT#l, "S0: TEST FILE"
1488 CC$="SCRATCH FILEJII":TT=1 :GOSUB 1848
14913
15013
15113 TT=21
15213 OPEN 4.8,4,"#"
15313 N~I~=( 1+RND(T I ) .254+NN~) AND255 :PR INTIT1 , "B-P" ; 4; NN~
15413 NN$="":FOR 1=1 TO 255:NN$=NN$+CHR$(I):NEXT
1550 PRINT# 4,NN$;
15613 PRINT# 1,"U2:";4;8;LT;13
15713 CC$="WRITE TRACK"+LTS:GOSUB 18413
15813 PRINT#I,"U2:";4;13;I;e
15913 CC$="WRITE TRACK 1" :GOSUB 1840
161313PRINT#I,"Ul:";4;e;LT;e
16113 CC$="READ TRACK"+LTS :GOSUB 18413
16213 PRINT#I,"Ul:";4;e;I;13
16313 CC$=" READ TRACK 1" :GOSUB 18413
16413 CLOSE 4
16513 : !
16613 :

52

167121PRINT"J.1 UNIT HAS PASSED"
168121PRINT" PERFORMANCE TEST!"

16913 PRINT")) PULL DISKETTE FROM"
171313PRINT")) DRIVE BEFORE TURNING"

1713 PRINT" POI~ER OFF."
172121END

1730
17413 :
175121PRINT" J.1CONTINUE (.../N)?";
17613 FOR 1=13 TO
17713 GET A$: IF A$="" THEt~ 177121
178121PRINT A$"JII"

17913 IF Af="N" THEN END
181313 IF A$=""''' THEN RETURN
18110

GOTO 17613

18210
183121
18413

PRIm CC$

18513

INPUT# 1,EN,EM$,ET,ES

18613

PRUITTAB( 12)" "EN; Et1$; ET; ES; ""

187121

18813
18913

191313

19113
19213
19313
1940
19513
19613
19713

19813

19910

21300
20113
21320
20313
2040
2050

212160

EN<2 THEN RETURN

IF
PRINT"JII UNIT IS FAILING"
PRINT"JII PERFORMANCE TEST"

TM$=TI$:GOSUB 175e:TI$=TM$:RETURN

PRINT"WRITING DATA"
FOR 1=1131310TO 2ee13:PRINT#CH,I:NEXT
GOSUB185e
CLOSE CH:RETURN

PRun"READum DATA"

GETA$
FOR 1=1131313TO 213130

INPun CH,J

IF JOI THEN PRItn"~EAD

t.IEXT

GOSUB

CLOSE CH: RETUR~I

50:GET A$:NEXT

ERROR:!!!":GOSUB 18513

18513

53

APPENDIX D: DISK FORMATS

NOTE
Not to scale

54

1540/1541 Format: Expanded Viewof a Single Sector

Block Distribution by Track

2040,3040

Track number

I to 17 o to 20

18 to 24 o to 19 20
25 to 30
31 to 25 o to 16

4040

Track number

1 to 17

18 to 24
25 to 30 o to 17 18
31 to 35

8050 Block or

Track number

1 to 39 o to 28
40 to 53
54 to 64 o to 24

65 to 77

1540/1541 BAM FORMAT

Blockor

Sector Range

o to 17

Block or

Sector Range

o to 20
o to 18

o to 16 17

Sector Range

o to 26 27

o to 22

Total
21

18
17

Total

21

19

Total
29
25

23

Track 18, Sector O.

BYTE

0,1 18,01

2 65
3 0
4-143

*1

=available block

O=blocknot available

(each bit represents one block)

CONTENTS

DEFINITION

Track and sector of first directory block.
ASCIIcharacter A indicating 4040 format.
Null flagfor future DOSuse.
Bit map of available blocks for tracks 1.35.

55

* STRUCTURE OF SINGLE DIRECTORY ENTRY

BYTE CONTENTS
0

128+type

File type OR'ed with $80 to indicate properly
closed file.

TYPES:

DEFINITION

0= DEleted
I = SEQential

2 = PROGram

3 = USER
4 = RELative

1-2 Track and sector of Ist data block.
3-18
19-20

File name padded with shifted spaces.
Relative file only: track and sector for first side

sector block.
21
22-25
26-27

Relative file only: Record size.

Unused.

Track and sector of replacement file when OPEN@

is in effect.

28-29

BYTE

0.1
2-256

SEQUENTIAL FORMAT

Track and sector of next sequential data block.
254 bytes of data with carriagereturn as record terminators.

Number of blocks in file: low byte, high byte.

DEFINITION

BYTE

0,1
2-256

56

PROGRAM FILE FORMAT

DEFINITION

Track and sector of next block in program me.
254 bytes of program info stored in CBMmemory format (with

key words tokenized). End of file is marked by three zero bytes.

1540/1541 DIRECTORY HEADER

Track 18, Sector O.

BYTE CONTENTS DEFINITION

144-161
162-163
164 160
165-166

166-167 160
177-255

Note: ASCII characters may appear in locations 180 thru 191 on some diskettes.

BYTE

0-1
2-31
34-63
66-95
98-127
130-159
162-191

194-123

226-255

50,65

0

DIRECTORY FORMAT

Track 18, Sector 1

Disk name padded with shifted spaces.
Disk 10.

Shifted space.
ASCIIrepresentation for 2A which is DOS

version and format type.
Shifted spaces.
Nulls, not used.

DEFINITION

Track and sector of next directory block.
*File entry 1
*File entry 2

*File entry 3
*File entry 4
*File entry 5
*File entry 6
*File entry 7
*File entry 8

57

DATA

RELATIVEFILEFORMAT

BLOCK

BYTE

0,1

2-256

SIDE SECTOR BLOCK

BYTE

0-1
2
3
4-5
6-7
8-9

10-11

12.13
14-15
16-256

Track and sector of next data block.
254 bytes of data. Empty records contain FF (all binary ones) in

the first byte followed by 00 (binary all zeros) to the end of the
record. Partially filled records are padded with nulls (00).

Track and sector of next side sector block.
Side sector number (0-5)

Record length
Track and sector of first side sector (number 0)
Track and sector of second sidesector (number 1)
Track and sector of third side sector (number 2)
Track and sector of fourth side sector (number 3)
Track and sector of fifth side sector (number 4)
Track and sector of sixth side sector (number 5)
Track and sector pointers to 120 data blocks

DEFINITION

DEFINITION

58

VIC-1541 User's Manual Errata Sheet.

INTRODUCTION

Commodore is constantly trying to bripg you the most efficient and reliable
computer in the world today. Alongwit~ the hardware improvements that come
from practical applications of the 154i disk drive inthe marketplace, the docu-
mentation should also reflect any changes and/or improvements that occur.
This is the most up-to-date information available for your 1541 disk drive.The
changes listed here s~ould be used to replace the comparable information in
your User's Manual..~Future updates will normally be available through the
Commodore User's Magazines(COMMODOREand POWERPLAY) as well as
the COMMODOREINFORMAT~ONN~TWORKon CompuServe.

The format ofthis update is as follows:
A. 1. Pageand Paragraphor Section ofthe VIC-1541User's Guide.

2. Oldinformation.

3. Newinformation.

Example:
A. 1. P.3, INTRODUCTION,paragraph 5

2. ... use your Commander 64 or VIC20 User's Guides. . .

3. ... use your Commodore 64 or VIC 20 User's Guides. . .

The followinglistingis performed innumerical order by page.
A. 1. P. 3, INTRODUCTION,paragraph 5

2. ... use your Commander 64 or VIC20 User's Guides. . .

3. ... use your Commodore 64 or VIC 20 User's Guides. . .

B. 1. P. 4, SPECIFICATIONS,paragraph 2, line 6

2. The "pipeline" makesthe disk abot to process commands. . .

3. The "pipeline" makes the disk able to processcommands. . .

C. 1. P. 7, CONNECTIONOF CABLES,paragraph 3, line 3

2. ... at one time, read chapter 8 . . .

3. ... at one time, read chapter 9 . . .

-

D. 1.

2.

3.

E. 1.

2.

3.

F.

2.

3.

G. 1.

H.

I. 1.

P. 9, USINGWITHA VIC20 ORCOMMODORE64, last paragraph
. . .explanation of the U (user)commands in chapter 7.
. . .explanation of the U(user) commands in chapter 8.

P. 10, EXAMPLES,example 3
LOADA$, J K
LOADA$, J, K

1.

P. 13, FORMATFOR THE SAVECOMMAND,first paragraph,line 1
Seethe LOADcommand (pages &
Seethe LOADcommand (page10) for an explanation. . .

P. 13, FORMATFOR SAVEWITHREPLACE:,example

2.

SAVE"=0:" + name$, device#, command#

3.

SAVE"@O:" + name$, device#, command#

1.

P.14, FORMATFOR THE OPENSTATEMENT:,example

2.

OPENftle#, device#, (command) channel#, text $

3.

OPENftle#, device#, channel#, text $

P. 15, paragraph after EXAMPLESOF OPENSTATEMENTS:,line 4

2.

. . . the disk drive, which LOADsit onto the diskette.

3.

. . .the disk drive,from whichit goesto the diskette.

) for an explanation. . .

J.

K.

L. 1.

1.

P. 19, CLOSE-- NOTE: (paragraph3 on p. 19), line 4

2.

CLOSE 15: OPEN 15,8,15: CLOSE15.

3.

OPEN 15,8,15, "I".

1.

P. 20, EXAMPLESOF OPENINGSEQUENTIALFILES:

2.

OPEN2,8,2, "ODATA,S,W"

3.

OPEN2, 8, 2, "O:DATA,S, W"
P. 20, EXAMPLESOF OPENINGSEQUENTIALFILES:

2.

OPEN8, 8, 8, "OProgram,P, R"

3.

OPEN8, 8, 8, "O:PROGRAM,P, R"

M. 1. P. 23, READINGTHE DIRECTORY,sampleprogram, line 10

2. 10 OPEN1, 8, 2, "s

3. 10 OPEN1,8,2, "$

N. 1. P.24,TABLE5.1,line4-143

2. 4-143 Bit map of availableblocks for trace 1-35

3. 4-143 * Bit map of availableblocks for trace 1-35

O. 1. P. 27, TABLETOPOF PAGE27

2.

3. Table6.1 TRACKANDBLOCKFORMAT

P. 1. P. 30, SAMPLEPROGRAMWRITING10 RANDOM-ACCESS.. . ,

lines40, 90, 100, 120, 130, 140

2. 40 A$="Record Contents #"
90 T=l : S=1

100PRINT# 15, "B-A:" 0, T, S
120 IF A=65 THENT=C: S=D: GOTO 100

130PRINT#15, "B-W:" 5,0, T,S

140 PRINT#4, T "," S

3. 40 A$="RECORDCONTENTS#"
90 T=1: B=1

100 PRINT# 15, "B-A:" 0, T, B
120 IFA=65THENT=C: B=D:GOTO 100

130PRINT# 15, "B-W:" 5,0, T, B
140 PRINT#4, T;B

Q. 1. P. 31-32 SAMPLE PROGRAM WRITING 10 RANDOM-

ACCESS..., lines40, 100, 110, 130, 140, 150

2. 40 A$="Record Contents #"
100 T=1 : S=1

110PRINT# 15, "B-A:" 0 ;T;S
130 IF A=65THENT=C : S=D: GOTO110

140PRINT# 15, "B-W:" 5,0, T; S
150PRINT# 4, T " ," S

3. 40 A$="RECORDCONTENTS#"
100 T=1 : B=1

110PRINT# 15, "B-A:" 0; T; B

130 IFA=65THENT=C: B=D: GOTO 110

140PRINT# 15, "B-W:" 5; 0; T;B
150PRINT#4, T;B

1.

R.

2.

3. RENAME

P.41, APPENDIXA: DISKCOMMANDSUMMARY,line3
NAME

"RO:new name. . .

"RO:newname. . .

S. 1.

2.

3.

1.

T.

2.

3.

U.

1.

2.

3.

P.46, 72:DISKFULL,lines2-3

. . .152entriesfor the 2040,3040,and4040or 243entriesforthe

8050 . .. .whentwoblocksareavailableonthe 8050to . . .

. . . 144 entries for the 1541 . . . .when two blocks areavailableon

the 1541to ...

P.46, 73:DOSMISMATCH,titleline
DOSMISMATCH(73,CBMDOSV2.58050)

(73,CBMDOSV2)for

4040

DOSMISMATCH(73,CBMDOSV2.61541)
P.46, 74:DRIVENOTREADY,line1

Anattempthasbeenmadeto accessthe 8050DualDriveFloppyDisk.
Anattempthasbeenmadeaccessthe 1541SingleDrive.. .