MITS 88-DCDD Operator's Manual

2450 A!amo SE Albuquerque. NM 87t06

PRELIMINARY DOCUMENTATION RELEASE

THE FOLLOWING INFORMATION IS A PRELIMINARY RELEASE ONLY.

THE COMPLETE THEORY OF OPERATION WILL BE ADDED TO THE ASSEMBLY MANUAL AT A LATER DATE. THE OPERATORS MANUAL

AND DOS DOCUMENTATION WILL BE DEVELOPED IN A SINGLE MANUAL ALSO. BOTH OF THESE, AND ANY UPDATES TO THIS ENTIRE SYSTEM DOCUMENTATION WILL BE SENT IMMEDIATELY UPON THEIR PRINTING DATE.

OISK OPERATORS MANUAL

INSCRIPTION OF SYSTEM A) DISK SPEC SHEET B) OISK SYSTEM BLOCK DIAGRAM DESCRIPTION

1. CONTROLLER BOARD 1: Controller Board 1 does all input functions to the ALTAIR

bus (Read Data, Sector Data, Status Information), as well as Control Addressing of all Disk to ALTAIR I/O.

2. CONTROLLER BOARD 2: Controller Board 2 performs all output functions from the

ALTAIR bus (Write Data, Disk Control, Disk Enable and Drive Selection).

3. INTERCONNECT CABLE:

An 18 pair flat cable with two 37 pin connectors, a male on one end, a female on the other. This cable connects the Disk Drive to the ALTAIR Disk Controller and "Daisy Chains" one Disk Drive to another in multiple Disk systems.

4. OISK DRIVE CABINET: a) POWER SUPPLY:

The Disk Drive Cabinet contains a power supply for powering the Disk Buffer and Disk Drive.

b) THE DISK BUFFER:

The Disk Buffer board contains the necessary line drivers and receivers for interconnection with long cables to the Disk Drive. In addition, it contains the Disk Drive Address circuitry that allows the Controller to select one of 16 Disk Drives.

The Disk Buffer board also contains the line drivers for connection of multiple Disk Systems.

c) THE DISK DRIVE:

The Disk Drive, a Pertec F0-400, contains the mechanism and electronics that actually reads ar.d writes data on the Diskette.

CONNECTION OF OISK SYSTEM: A) CONTROLLER BOARDS:

1. Items Supplied: a) CONTROLLER BOARD 1 (white vert strips)

b) CONTROLLER BOARD 2 (with short cable wired to it) c) CONTROLLER CABLE (with 37 pin on one end, 3 Molex connec-

tors on the other end)

d) Connector Mounting Bracket and Hardware

2. Connection of Controller Boards a) Take cover off ALTAIR (power off!)

b) Feed Molex (flat) connector ends of Controller cable through

hole in back of ALTAIR on connector panel: (37 pin con- nector outside chassis, molex connectors inside chassis).

c) Lay board 1 flat in front of you on the ALTAIR chassis with

components up and stab connector to your right (as facing the front of the ALTAIR).

d) Take the short wired cable of board 2 and connect it to the

20 pin connector on board 1 (note polarization key of

connector and missing pin on the PC board). e) Place board 2 flat, to the left of board 1. f) Connect 20 pin Molex connector on the Controller cable to

the 20 pin connector on board 2. Note Keying. g) Take the 10 pin connector on the Controller cable with the

orange and yellow wires connected to it and connect it

to the 10 pin connector on board 2. Note Keying. h) Take the remaining 10 pin connector on the Controller cable

with white and gray wires on it and connect it to the

10 pin connector on board 1. Note Keying. i) Take both boards, hold together and slide into slots, with

board 1 on right, board 2 on the left. Be sure wires

from connector go out between card guides, and do not

catch on card guides, j) Push cards firmly into connector in ALTAIR mother board, k) Install 37 pin connector in bracket and on back of ALTAIR,

straddling 2 connector holes. Use #4-40 x 5/16 screws,

lockwashers and #4-40 nuts.

B) DISK DRIVE CONNECTION TO ALTAIR:

Take the 6 ft. flat cable with 1 male and 1 female connector; connect male end to Disk Controller connector on ALTAIR, and female end to connector on the Oisk Drive marked "To Controller".

THE ALTAIR FLOPPY

D!SK SYSTEM

The ALTA/R Disk offers the advantage of nonvolatile memory plus relatively fast access to datu The AL7A/R Disfc Controffer consists of tv,o PC boards lover 60 IC s) that fit in [he AL7A1R

nect to the disk through a 37 pin connector mounted on the back of the ALTAIR Data is transferred to and from the disk senally at 250K bits sec The disk controller converts the senal data to and from Sbit parallel words (one word every 32 « sec! The ALTA/R CPU transfers the data, word by word to and from memoty. depending on wnether the disk is reading or writing The disk controller also controls all mechanical functions of the disk as well as presenting disk status to the computer All timing

tasks Since the /loppy diskette is divided into 32 sectors, a hardware interrupt system can be enabled to notify the CPU at

The Disk Dnve unit, using a PERTEC FD400 mounted in an Optima case 15'?" high—same depth and width as computer), includes a poaer suppfy PC board and a 8u//er Address Line

temperature ior continuous operation The disk dnve cabinet has two 37 pin connectors on the back panel, one is the input from the disk controller, the other is the output to additional disk dnves Up to ]6 dnves may be attached to one controller

The Mb DCDD consists of the disk controller and one disk dnve with an interconnect cable The

Disk is one disk dnve for

adding storage capability to the

DCDD and includes the inter

The AL7AJR Disk Format allows storage of over 300.000 bytes. Since the disk is hard sectored 132 sectors for each track), we wnte 137 byies on each sector. 9 of which are used internally [tracks checksum) leaving 128 data bytes per sector. 4096 per track One floppy diskette is supplied with each drive: extra flop- pies are available for purchase A so/Mare driver for the floppy disk is available at no charge and is supplied with the disk as a source listing The disk operating system—which has a complete file structure and utilities for copying, deleting and sorting files—costs extra Extended BASIC. which uses random and se- quential tile access for the floppy disk, is also available.

Speed Access Times

Head Life

Disk Life

Rate Power

Diskette

Specifications

360 rpm 1166.7 ms/rev)

Track to track. 10 ms Head settle. 20 tin

Average time to read or

write. 400 nis

Worst case. 1 sac Over 10.000 hours of head

to disk contact

Over 1 million passes/track

250K bits/sec 117VACH0W

Dysan 101 floppy disk. 77 tacit*

DISK SYSTEM BLOCK DIAGRAM

10 NEXT DISK DRIVE

DISK CONTROLLER BLOCK DIAGRAM

SHEET I EXTERNAL CONNECTIONS AND AOORESS SELECT

A00HE99

> /

LIHES < LIWCS

CLOCK

^as" — ooivt

OISK

CONTROLLER

AOORESS

SELECT

CIRCUIT

READ

CIRCUIT

STATUS

CIRCUIT

SECTOR/

tNOEX

CIRCUIT

ouT on [cot

CLOCK

r I

[

' ' e LINES

PIMT OH ALTM"

Vt7 IMPUT

ALU

POC

BOARD 2

WRITE

CIRCUIT

I WHITE MT4

! o*.*

DISK

DRIVE

SELECT

o*.a

DISK

DRIVE

SELECT

o*c ^

DISK

DRIVE

SELECT

0*0 ^

OHK ENA9LE

STEP IX STEP IX

FUNCTION FUNCTION

CONTROL CIRCUIT

TBI* EMSE ?

OHIVE

DISK CONTROLLER BLOCK DIAGRAM

SHEET 2 INTERNAL CONNECTIONS

80AR0 I

ALTAIR DISK CONTROLLER I/O INFORMATION

A. Address codes for I/O

Address Mode

010

Out Select, latches and enables controller

and disk drive.

010

Indicates status of disk drive and controller.

011 Out Controls disk function.

011 In Indicates sector position of disk

012

Out

Write data.

012

Read data.

8. Definitions (In order as listed above)

1. Selection of Disk Drive "OUT" on CH #010 D0 LS8 Enables 1 of 16 drives (each drive has a unique ad-

D1 dress, selected by 4 jumper wires) and enables con- D2 troller (on disk drive buffer P.C. card). D3 MSB

D4 D5 Not used, don't care.

D7 Clears disk control if set to 1 (D0-D6 don't care).

Disables disk control. Oisk control also cleared by opening door of disk drive or turning disk drive power off.

NOTE: a) If disk drive door is open, drive and controller

cannot be enabled.

b) If disk power is off, drive and controller cannot

be enabled.

c) If disk interconnect cable is not connected between

the controller and the drive, drive and controller cannot be enabled.

C) MULIIPLL DISK DRIVE CONNECTION:

1. With multiple Disk Drives, the Disks should have sequential addresses (i.e., for a .1 drive system you should have Disks

with addresses 0, 1, and 2). They may be connected in any or- der. There serial # sticker has the Disk Address written on

it. The Disk Address is determined by four jumper wires in the Disk Buffer P.C. card inside the Drive, and may be changed.

2, Connect the Disks by using the 6 ft. flat cable. Connect the

male connector to the connector marked "From Next Disk" on the Disk Drive connected to the Controller. The other end of the cable connects to the next Disk Drive connector marked "To Con- troller". This procedure is repeated for added Disk Drive.

III. USING THE DISK DRIVE:

A) DISKETTE INFORMATION:

1. Always keep Diskette in envelope when not in use.

2. Keep Diskette away from heat, magnetic fields (flourescent lights, power transformers, etc.) and dust and dirt.

3. Never touch recording surface of Diskette (opposite label side).

4. Always mark your Diskette with what is on them. Use adhesive labels, but don't write on them after they are attached to the Diskette.

5. The Diskette used is hard Sectored (32 Sector holes, 1 index

hole). Blank Diskettes are available from MITS for $15.00 each. The Diskettes are not IBM compatible.

B) OPERATING THE DISK DRIVE:

1. Open door to Disk Drive by pulling out and down.

2. Insert Diskette into Drive with label side up, making sure

it catches on retaining tab.

3. Close door to Disk Drive.

4. If Disk power is on, wait 10 seconds, after closing door before activating any programs to access the Disk. Wait 10 seconds after turning power on with Diskette in Drive before activating any programs to access the Disk. This is to allow motor speed to stabilize.

5. NEVER: open Disk Drive door or turn power off when Disk Enable

and Head Load lights are on. There would be a good possibili- ty that you would interrupt the software during a write func- tion, and destroy data on the Diskette.

6. Consult software documentation on methods used to load basic or

use software. For applications where the user wishes to

write his own software. See last section, "Controller I/O

Information".

2. Status (010 - INP) indicates disk status when drive and controller enabled. Also gives valid "INTE" status (05) from the ALTAIR bus

when controller enabled. True condition = 0, False = 1. All false if disk and controller are not enabled, and all false if

no disk in drive. D0 - ENWO - Enter new Write data - indicates write circuit is ready

for new data byte to be written. It occurs every 32 us and starts 280 ps after sector true (when Write enabled). It is reset by outputting to the Write data channel (012).

Dl - Move Head - Indicates head movement allowed when true (step

IN, step OUT,). Goes false for 10 ms, true 1 ms, false 20 ms after step command. May step every 10 ms. Goes false for 40 ms after head load. Goes false during Write and 475 us after Write to allow completion of trim erase.

D2 - HS - Head Status - True 40 ms after head loaded or step command

Ii*f stepping with head already loaded). Indicates when head

is properly loaded for reading and writing. Also enables sec- tor position channel when true.

03 - Not Used, = 0. D4 - Not Used, = 0. D5 - INTE - Indicates interrupt enabled. D6 - TRACK 0 - Indicates when head is on outermost track.

D7 - NROA - New read data available - indicates that the read cir-

cuit has 1 byte of data ready to be taken from the read data channel (012). After the SYNC* bit is detected, it occurs every 32 ps and is reset by an input instruction on channel

012. The byte containing the SYNC bit is the first byte

read from the disk.

* See "Write Enable"

Control (011 - Out) - Controls Disk operations when disk drive and controller enabled. A true signal, logic 1, on a data line will control the disk as follows:

00 - Step IN - steps disk head in one position to higher numbered

track.

D1 - Step OUT - steps disk head out one position to lower numbered

track.

D2 - Head Load - loads head onto disk - enables sector position

status.

D3 - Head Unload - removes head from disk surface, may be unloaded

immediately after "Write Enable" (write and trim erase circuits hold head loaded until through).

D4 - ^E - Interrupt Enable - enables interrupts to occur when SR0

true (see sector definition).

D5 - H) - Interrupt Disable - disables interrupt circuit. Interrupt

circuit also disabled by clearing disk control.

D6 - HCS - Head Current Switch - must be true when outputting a write

instruction with the head on tracks 43-76. This reduces head current and optimizes resolution on inner tracks (automatically reset at end of writing a sector).

D7 - Write Enable - initiates write sequence as follows:

1. Disk selected and enabled, head loaded, enabling sector status.

2. (Sector True) detected for desired sector, write circuit

enabled by software.

3. 200 us from Write Enable, trim erase automatically turned

on. 280 us from start of sector, "ENWD" goes true, sync byte written by software.

4. First byte written always has most significant (D7) bit A

"1" (SYNC Bit) (most sifnificant bit written first).

5. ENWD goes true every 32 us. MAX. no. of data bytes per

sector 137 (including SYNC).

6. Last or 138th byte written must be a 000. This will be

written for the remainder of the sector. Ignore "ENWD" from this point to end of sector.

7. At end of sector, the write circuit automatically disabled,

trim erase disabled 475 us later.

NOTE: a) Write circuit will continue writing last byte out-

putted on CH #012 to the end of that sector.

b) Head may be unloaded anytime during write cyclr it* no

read or write function is cxpcctcd after current write cycle. Once Write is enabled, it holds the head loaded for the required time. (For writing and trim erase).

4. Sector Position (011 - INP) with disk drive and controller enabled, and 40 ms after head is loaded, the sector information is as follows

00 - SR0 - Sector True - True when = 0, and is 30 ps long. The write mode should begin as close as possible to the time that D0 goes true. Write data will be requested 280 ps after D0 goes true. Read data will be available 140 ps after SR0 goes true.

SECTOR #

2 3

U1-SR1-

D2-SR2-

0 0

1 1

D3-SR3-

0 0 0

D4-SR4-

0 0

D5-SR5-

0 0 0 0

b. Write Data (012-OUT) Outputted on the "ENWD" status request.

6. Read Data (012-IN) Inputted on the "NRDA" status flag.

( )

READ/URITE TIMING

DURING READ OR URITE FUNCTION

NLh READ DATA AVAILABLE

(NRDA) ) r^

[_]

false ENTER NEh URtTE DATA (ENWD) J4-6 (Board 2)

SECTOR* TRUE -^J— soVs

(BOARD 1) .

F4 - S

WHITE DATA ENABLE

(BOARD 1)

WRITE EhABLEF.r.

(BOARD 2) E2

- 9

EKhD (Board 2)^-6

32 ps-

] itrue

—J k- DOWN TIME DEPENDENT ON SOFTWARE CYCLE TIML

TRIM ERASE

(BOARD :)

READ CLEAR

(BOARD 1)

Jl -9

-4

2SO

tJS

j—-

200 tJS-*-

—-j ! 40)JS ——

5.2 MS

47 5 PS-

NRDA(BOARD l)a:-n

2ao ps

*********** ERRATA SHEET ***********

ALTAIR FLOPPY DISK

DRIVE & CONTROLLER - HARDWARE DOCUMENTATION

March 1976

THE FOLLOWING CHANGES HAVE BEEN MADE TO THE ABOVE TITLED MANUAL ON THE PAGES INDICATED.

PAGE 32: No heat-sink should be used for either XI or X3. Mount both

of these regulators directly to the board.

PAGE 95: Use a length of wire and connect the two pads labeled +8V to-

gether along the bottom edge of the board.

IT IS GENERALLY A GOOD IDEA TO GO THROUGH YOUR MANUAL AMD MARK THESE CHANGES ON THE PAGES INDICATED BEFORE BEGINNING THE ACTUAL PROCESS OF ASSEMBLING YOUR UNIT.

HITS, Inc.

3/16/76

^k ccntro^er assembly procedure

ASSEMBLY H!MT$

Before beginning the construction of your unit, it is important that you read the "M!TS Kits Assembly Hints" booklet included with your kit. Pay particular attention to the section on soldering, because most problems in the Altair occur as the result of poor soldering. It is essential that you use the cor- rect type of soldering iron. A 25-30 watt iron with a chisel tip (such as an Ungar 776 with a 7155 tip) is recommended in the assembly hints booklet.

Some important warnings are also included in the hints booklet. Read them

carefully before you begin work on your unit -- failure to heed these warnings

could cause you to void your warranty.

Check the contents of your kit against the enclosed parts list to make sure you have all the required components, hardware and parts. The components are

in plastic envelopes; do not open them until you need the components for an assembly step. You will need the tools called for in the "Kits Assembly Hints" booklet.

As you construct your kit, follow the instructions in the order they are presented in the assembly manual. Always complete each section before going on to the next. Two organizational aids are provided throughout the manual to assist you: 1) Boxed-off parts identification lists, with spaces provided to check off the components as they are installed; 2) Reproductions of the silk screens showing a) previously installed components, b) components being installed and c) components yet to be installed, (see below)

previously installed components

components yet to be installed

components bei

installed

-un inE

COMPONENT INSTALLATION METHODS

This section of the manual describes the proper pro- cedures for installing various types of components in your kit.

Read these instructions over very carefully and refer back to than whenever necessary. Failure to properly install components may cause permanent

damage to the component or the rest of the unit;

it will definitely void your warranty.

More specific instructions, or procedures of a

less general nature, will be included within the

assembly text itself. Under no circumstances should you proceed with an

assembly step without fully understanding the pro- cedures involved. A little patience at this stage will save a great deal of time and potential "head- aches" later.

PIM t

PIN I

°o

PIM I

INTEGRATED CIRCUITS (IC's) CAN COME WITH ANY ONE OF, OR A COMBINATION

OF, SEVERAL DIFFERENT MARKINGS. THESE MARKINGS ARE VERY IMPORTANT IN

DETERMINING THE CORRECT ORIENTATION FOR THE IC's WHEN THEY ARE PLACED

ON THE PRINTED CIRCUIT BOARDS. REFER TO THE ABOVE DRAWING TO LOCATE

PIN 1 OF THE IC's, THEN USE THIS INFORMATION IN CONJUNCTION WITH THE INFORMATION BELOW TO PROPERLY ORIENT EACH IC FOR INSTALLATION.

j WARNINGl INCORRECTLY ORIENTED IC's MAY CAUSE PERMANENT DAMAGE!

E C E

THE DRAWING ON THE LEFT INDICATES VARIOUS METHODS USED TO SHOW THE POSITION OF IC's ON THE PRINTED CIRCUIT BOARDS. THESE ARE SILK-SCREENED DIRECTLY ON THE BOARD. THE ARROWHEAD INDICATES THE POSITION FOR PIN 1

WHEN THE IC IS INSTALLED.

IC Installation

All ICS must be oriented so that the notched end is toward the end with

the arrowhead printed on the PC board. Pin 1 of the IC should correspond with the pad marked with the arrowhead. If the IC does not have a notch on one end, refer to the chart on the proceeding page for the identification of Pin 1.

lb prepare ICs for installation:

All ICs are damaged easily and should be handled carefully — especially static- sensitive MOS ICs. Always try to hold

the IC by the ends, touching the pins

as little as possible.

Mien you remove the IC fran its holder, CAREFULLY straighten any bent pins using needle-nose pliers. All pins should be evenly spaced and should be aligned in a straight line, perpendicular to the body of the IC itself.

1. Orient the IC so that Pin 1 coincides with the arrowhead on the PC board.

4. Tape the IC into place on the board with a piece of masking tape.

5. Turn the board over and solder each pin to the foil pattern on the back side of the board. Be sure to sol- der each pin and be careful not to

leave any solder bridges.

6. Turn the board over again and remove the piece of masking tape.

2. Align the pins on one side of the IC so that just the tips are inserted into the proper holes on the board.

3. Lcwer the other side of the IC into place. If the pins don't go into their holes right away, rock the IC back, exerting a little inward

pressure, and try again. Be patient. The tip of a small screwdriver may be used to help guide the pins into place.

S-3ien the.

tips of all the pins have been started into their holes, push the IC into the board the rest of the way.

Resistor installation

Resistors have four (or possibly five) color-coded bands as represented in the chart below. The fourth band is gold or silver and indicates the tolerance. NOTE: In assembling a MITS kit, you need only be concerned with the three bands of color to the one side of the gold or silver (tolerance) band. These three bands denote the resistor's value in ohms. The first two bands correspond to the first two digits of the resistor's value and the third band represents a multiplier.

For example: a resistor with red, violet, yellow and silver bands has a value of 270,000 ohms and a tolerance of 10%. By looking at the chart below, you see that red is 2 and violet 7. By multiplying 27 by the yellow multiplier band (10,000), you find you have a 270,000 ohm (270K) resistor. The sil- ver band denotes the 10% tolerance. Use this process to chose the correct resistor called for in the manual.

2ND BAND

VIOLET

1ST BAND

RED

4TH BAND

SiLVER

3RD BAND

YELLOW

RESISTOR COLOR CODES

BANDS

3rd BAND

COLOR

1&2

(Multiplier)

Black

0 1

Brown

Red

10^

Orange

10^

Yellow

4 10"

Green 5

105

Blue

106 Violet 7 10? Gray 8

10S White 9

109

Use the following procedure to install the resistors onto the boards. Make sure the colored bands on each resistor match the colors called for in the list of Resistor Values and Color Codes given for each board.

1. Using needle-nose pliers, bend the leads of the resistor at right an-

gles to match their respective holes on the PC board.

2. Install the resistor into the cor- rect holes en the silk-screened side

of the PC board.

3. Holding the resistor in place with one hand, turn the board over and

bend the two leads slightly outward.

4. Solder the leads to the foil pattern

on the back side of the board; then clip off any excess lead lengths.

Capacitor Installation A. Electrolytic and Tantalun Capacitors

Polarity requirements must be noted on the electrolytic capacitors and the tan- talum capacitor before they are installed.

The electrolytic capacitors contained in your kit may- have one or possibly two of three types of polarity markings, lb determine the correct orientation, look for the following.

One type will have plus (+) signs on the

positive end; another will have a band or a groove around the positive side in addition to the plus signs. The third

type will have an arrw on it; in the tip

of the arrow there is a negative

(-)

sign and the capacitor must be oriented so the arrow points to the negative polarity side

The tantalum capacitor is metallic in appearance and smaller than the elec- trolytic capacitors. Its positive end has a plus sign on it or a red dot.

Refer to the chart included for each

board for correct Capacitor Values and

install the electrolytic capacitors and tantalum capacitors using the following

procedure.

1. Bend the two leads of the capacitor at right angles to match their re- spective holes on the board. Insert the capacitor into the holes on the silk-screened side of the board. Be sure to align the positive polarity side with the "+" signs printed on the board.

2. Holding the capacitor in place, tum the board over and bend the two leads slightly outward. Solder the leads to the foil pattern and clip

off any excess lead lengths.

B. Ceramic Disk Capacitors Refer to the chart included for each

board for correct Capacitor Values, and install the ceramic disk capacitors using the following procedure.

1. Choose the correct value capacitor

and straighten the two leads as necessary to fit their respective holes on the PC board.

2. Insert the capacitor into the cor-

rect holes fron the silk-screened side of the board. Push the capaci- tor dwn until the ceramic insula- tion almost touches the foil pattern.

3. Holding the capacitor in place, tutrn the board over and bend the two leads

slightly outward.

4. Solder the two leads to the foil

pattern on the back side of the board; then clip off any excess lead

lengths.

Transistor Installation

Diode Installation

lb install transistors, use the foll- owing instructions.

NOTE: Always check the part number of each transistor before you install it.

(See listing of Transistor Part Numbers for each board.) Sane transistors look identical but differ in electrical char-

acteristics, according to part number.

If you have received substitute part

numbers for the transistors in you kit, check the Transistor Identification Chart which follows these instructions

to be sure you make the correct sub-

stitutions.

NOTE: Always make sure the transistor is oriented so that the emitter lead is installed in the hole on the PC board labeled with an "E." lb determine

which lead is the emitter lead, refer to

the Transistor Identification Chart.

1. After the correct transistor has been selected and the leads have been properly oriented, insert the transistor into the holes on the silk-screened side of the board.

2. Holding the transistor in place, tum the board over and bend the three leads slightly outward.

NOTE: Diodes are marked with a band on

one end indicating the cathode end.

Each diode must be installed so that the end with the band is oriented towards the band printed on the PC board. Fail- ure to orient the diodes oorrectly may result in permanent damage to your unit.

Use the following prooedure to install diodes onto the board. Refer to the list of Diode Part Numbers included for each

board to make sure you install the correct diode each time.

1. Bend the leads of the diode at right angles to match their respective holes on the board.

2. Insert the diode into the correct holes on the silk screen, making sure the cathode end is properly oriented. Tum the board over and bend the leads slightly outward.

3. Solder the two leads to the foil pattern on the back side of the board; then clip off any excess

lead lengths.

3. Solder the leads to the foil pattern on the back side of the board; then clip off any excess lead lengths.

TRA.'iSISTOR IDENTIFICATION CHART

-rh-.

2N4410 EN4410 PN2907 2N2907 EN2907*

IN THE ILLUSTRATION ABOVE THE OUTLINE OF EACH TYPE OF TRANSISTOR IS SHOWN OVER THE PADS ON THE CIRCUIT BOARD WITH THE CORRECT DESIGNATION FOR EACH OF THE THREE LEADS. USE THIS INFORMATION TOGETHER WITH THE INFORMATION IN THE ASSEMBLY MANUAL FOR THE CORRECT ORIENTATION OF THE TRANSISTORS AS YOU INSTALL THEM.

THE FOLLOWING IS A LIST OF POSSIBLE SUBSTITUTIONS: IF ANY OTHERS ARE USED YOU WILL RISK DAMAGING YOUR UNIT:

2N4410 = EN4410 = CS4410 = CS4437, CS4438, TIS98, ST98, S38473 (NPN)

EN2907 = 2N2907 = PN2907 = ST2907, CS4439 (PNP) WHEN MAKING SUBSTITUTIONS, REFER TO THE ILLUSTRATION TO DETERMINE THE CORRECT ORIENTATION FOR THE THREE LEADS.

'Configuration of the leads on EN2907 may vary.

disk drive assembly procedure

t'A.'iK T<)t' M-:W;VAL

Remove the top from the Disk Drive case by withdrawing the two screws indicated in the drawing below. Slide the case top backwards, lifting the back slightly, to remove it entirely from the chassis.

Also remove the 4 screws in the side of

the case bottom, and remove the entire

chassis assembly.

DISK DRIVE BACK PANEL ASSEMBLY

Remove the back panel from the case by

withdrawing each of the four screws in

the comers of the panel. These four

screws are shown inserted in the draw-

ing below.

Save these four screws for remounting

the back panel later in the assembly

procedure.

Terminal Block Installation

Mount the terminal block to the back panel as shown in the drawing below. Use the screw sizes and other hardware indicated

in the drawing.

NOTE: Be sure that the back panel is

oriented as shown; be careful

not to mount the terminal block

on the wrong side of the panel.

Tighten all four screws firmly into place.

Transformer Installation

There are two transformers included in this kit. The larger of the two will be refered to as Tl, the smaller as T2.

Wire Preparation

Before mounting these transformers, the wires must-be cut to the proper length and screw-mount crimp terminals attached to each of them. There are also three wires which will not be used at all, and will be cut off at the transformer coil.

Refering to the drawing on the opposite page, cut the wires on transformers Tl and T2 to the lengths indicated. The three unused wires should be cut off at the point where they enter the trans-

former coil itself.

Next, as indicated in the bottom of the drawing, strip exactly 1/2" of insula- tion from each of the eleven wires and bend the exposed portion in half to 1/4".

There are several screw-mount crimp ter- minals included with this kit. These have a slot in one end and an insulated portion on the other end (usually red) for attaching wires. One of these crimp terminals must be attached to each of the eleven transformer wires.

Mounting

Refering to the drawings following the

"Transformer Wire Preparation" drawing, mount transformers Tl & T2 to the back panel.

NOTE: For proper orientation, transformer

Tl should have the two yellow wires

towards the top of the panel (with

reference to the drawings), and T2 should have the two black wires to- wards the top of the panel.

Be sure to install a terminal lug on transformer Tl as shown in the

drawing. This is a solder type

lug, and not the screw-mount type

used for the transformer wires.

Use the hardware indicated in the drawings

to mount the transformers and tighten the

screws firmly into place.

Insert one of the wires into one of the terminals as shown in the drawing. Push the wire in as far as it will go without distorting it or pushing it all the way through. NOTE: Save all wires that you cut oM

for later use. The wire should then be permanently con- nected to the terminal by either soldering it in place or crimping. To crimp the terminal use a crimping tool, if avail- able, or else flatten the insulated por- tion of the terminal as tightly as possible using pliers.

Prepare each of the eleven transformer wires in the above manner.

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MITS 88-DCDD Operator's Manual

Specifications and Main Features

Frequently Asked Questions

User Manual