Atari Mega 2 User guide

TABLE

OF CONTENTS

LIST

OF

SECTION

ILLUSTRATIONS

ONE--INTRODUCTION

Main

Conponents

Case

design

Differences

TWO..THEORY

Overview

Main

OF OPERATION

Systen

Microprocessing

GIue

Main

Direct

MFP Interrupt

Audio/Video

Video Video Display

GIue

Memory Control-Ler

Sound

Video Interface

from

520l1040ST

Menory

l4enory

subsystem

Shifter

Synthesizer

unit

Access

Control

Menory

11

t.2 t.2 I.5

2.t

2.2

2.3

2.4

2.5

2.6

Mega

Service

Manua1

Input/output

MIDI

Intelligent Parallel Interface

RS232

Disk Drive

Hard

Systen Startup

System Errors

Functional

Systen

Interface

Disk

block

clock

i.1

subsystens

Keyboard

Interface

diagran

diagra-m

Table

2.8

2.9

2.70

2.Lt

2.L2

2.L3

2.t4

2.15

2.L6

2.t7

of Contents

SECTION

THREE--TESTING

THE

MBGA

Overview

Test equipnent Test Configuration

Trouble-Shooting

Diagnostic

ST

Power-up

RAM test

ROM

Cartridge

test

Color test

Keyboard

MIDI test

RS232 test

test

Audio test

Tining test

DMA test

Floppy

Disk test

Printer/Joystick

Monitor

Res

High

Blitter test

Codes

test

port

Quick

Clock

Expansion

Error

dead

a

test

Reference

unit

3.1

3.2

3.4

3.6

3.7

3.9

10

3.

11

3.

3.r7

3.r2

13

3.

3.t5

3.16

3.L6

3.L7

3.r7

3.18

SECTION

Mega Service

FOUR--DISASSBMBLY/ASSEMBLY

FIVE-.SYMPTOM

Display

Disk

Keyboard

MIDI

R5232

Printer

Hard

Real

Blitter

Manual

CHECKLIST

problems

Drive

problens

problems

problens

Problems

Disk

Time

Problens

í.2

Problens

Clock

Problens

Table of

5.t

5.L

5.2

Contents

SECTION

SIX.-DIAGNOSTIC

FLOIlICHARTS

SECTION

SEVEN..PARTS

EIGHT-.SCHEMATICS

NINE--GLOSSARY

LIST AND

ASSEMBLY

AND

SILKSCREEI'I

DRAWINGS

Mega

Service

Manual

i.3

Tab1e of

Contents

LIST OF

ILLUSTRATIONS

FIG 1 FIG FIG FIG 4 FIG FIG FIG FrG

FIG

FrG

FIG

FrG 12

FIG 13

MEGA

COMPUTER

2 BATTERY COMPARTMEI.IT

BACK PANEL

3

I,EM

SIDE

TOP

5

BOTTOM OF

6

MEGA MOUSE

7

t{oNrron

I

MIDI PORTS

9

10 MoUSE/JOY

11 PRINTER

RS232 PoRT

EXTERNAL

KEYBOARD

OF

FIG 14 EXTERNAL

PANEL

KEYBOARD

poRr

PoRTS

PORT

FLOPPY

HARD DISK

PORT

1.1

L.2

1.3

r.3

1.4

1.5

2.7

2.8

2.9

2.LO

2.tL

2.L2

2.L3

FrG 15

16

FIG

Mega Service

FLJNCTTONAL

SYSTEM

Manual

CLOCKS

BLoCK

DTAGRAM

11 List

2.16

2.r7

Illustrations

of

SECTION ONE

INTRODUCTION

The Mega

2

conputers with

are

styled as

2 negabytes

Mega

and

disk

drive,

a

of RAM,

4 have

and an internal switching

cooling fan.

Since the

size

of its RAM,

refers

to both

Power Light

Mega

and

sinilar

nain CPU

4 are Motorola

architectures

unit

with a detached

the Mega 4 contains 4 negabytes. Both the Viega

a built-in 1 Megabyte

onty difference between

nar¡ual

this

products.

will

use

MC68000 nicroprocessor based

to the

520ST/

1040ST line. They

keyboard. The Mega 2 has

(720K

'

fornatted)

power

Mega 2

the

Mega

inch floppy

3,5

supply with built-in

Mega

and

generic

as a

'

Disk

Drive

Drive Busy Light

4 is the

tern

2

which

Mega

Service

Manua1

FIG. 1

ItIEGA

COMPUTER SYSTEM

1.1

Introduction

The main

the

components

Main board assembly

o

Disk drive

o

Power supply

o

RF Shield

o

CPU

o

Keyboard assembly

o

Interface board

o

Keyboard

o

Mouse board assembly

o

Mouse Plastics

o

of

CPU

Plastic case

KEYBOARD

Plastics

MOUSE

Mega 2 and

& cooling

(upper

assembly

(upper

CASE

lower)

and

(upper

DESIGN

fan

and

Mega

lower)

and

lower)

4 are:

lower)

the

Mega

Figures

keyboard

Battery

Cover

size AA Batteries

Service

1

thru 4

portion,

Housing

--

Manual

CPU

shows

and figure

the

shows the

7

+

(+)(-)

FIG. 2

BATTERY COMPARTMENT

r.2

portion

of the

mouse.

IUEGA,

6

ar¡d

5

Top

of

Computer

Introduction

shows

On/Off

lo

Power

loppy

I

Js

Printer

Frc.

BACK PANEL

3

Midi

ln

Mega

Service

Cartridge

Manual 1.3

Keyboard

FIG. 4

LEFT SIDE PANEL

Introduction

Function

Keys

Calculator

Keypad

¡oyst¡Jx

I

Port

Computer Jack

V

MouseiJoystick

I

Arrow

FIG.

TOP OF KEYBOARD

5

Keys

Bottom

Keyboard

of

Mega

Service

Manual

FIG.

BOTTOM OF KEYBOARD

5

1

.ll

Introduction

Clicking

Left Mouse

Button

FrG.

MEGA

7

UOUSE

Right Button

Mouse

Differences

New version of

o

o More o o o o o

nenory requiring

ReaI

tine

clock chip

Graphics Co-Processor

Internal expansion

Cooling

New

fan

styling with

case

T0S

fron

520ST/1040ST

74LS243

buffers on

& support circuit,

(BITtsLiT)

connector

detached

& support circuit

keyboard

MAD lines

Mega

Service

Manual

r.5 Introducti.on

SECTION

THEORY OF OPERATION

OVERVIEW

T!{O

The Mega 2 and

LSI

chip set,

ba¡rk of

one

the Mega 4. systen

(central processing

and case styling.

2 Mega-bytes of

Ttre hardware can be considered

Mega 4 share a coruDon architecture,

Input/Output subsystens

Main

System

Mc680o0 running at SMltz

o

192 Kbyte Read Only

o

2

o

Direct Menory

o o Systen

Interrupt control

o

Bit Mapped video display,

o

anywhere

BITBLiT

o

Monitor

o

Audio output:

o

Mega-byte

or 4

tining and

Audio/Video Subsystem

in nenory.

32O

support

x 200 x 200 x

400

a.

b. 640

c. 640

interface analog:

Ttre only difference

RAM, for a total of 4

unit ar¡d

.

Memory

Randon Access Menory

Access

programmable

support

Bus control

There

pixel, pixel, pixet,

16

4

nonochrone

using

are

color

RGB, Monochrone

sound chip

Mega-bytes of

as consisting of

support chips)

bytes of

l2k

three display

palette

îron

fron

with

!12

J

using the sa.ne

is the addition

RAM

nain

a

a¡rd several

RAM, relocatable

nodes available:

jL2

selectÍons

selections

voices

of

on

Mega

Input/Output Subsystens

Intelligent

o

Parallel

o

RS-232C serial

o

Port & connector

DMA

o

Hard disk

o

Musical

o

Digital

Time Clock with

ReaI

o

Port

ROM

o

Service

ManuaL

Keyboard

printer

drive

instrunent

Interface

2

with

interface

button

(Centronics)

interface

for

external

interface &

network connunication

(MIDI).

battery

Laser

backup

2.7

mouse/ioystick interface

drive

Printer

Musical

:

Theory of Operation

Instrunent

MAIN

SYSTEM

microprocessing

The

(ROM

general

data

and

purpose

Mega uses

The

bus,

Glue

important

computer.

thè

Clock

KHz clocks.

Video

generãtlsignals

to

use¿

register

operation

Interrupt

main system

RAM)

,

DMA controller.

the

Z4 Uit

(naned

component

address

functions

The

because

dividers--

tining--

in Gtue

(done

by

B-Lank,

wfrich

the

priority--

includes

systen

MicroProcessing

Motorola

bus

that

takes

for

nay be

Operating

the

control,

MC68000

nicroprocessor,

Glue

it holds

is

it

nay be

ttre

DE

the

(Display

the

involved

sumnarÍzed

Mtlz clock

I

video

written

System).

interrupts

fron the

intepupt

Unit

16 bit

running

systen

in nearly

as

and outputs

Enable),

display.

configUre

to

MFP

codeffisofpriorityonoutputsIP11andÍPL2tothe

interrupts,

no

68000.

These

interrupt,

leve1s

HSYNC

correspond

interruPt.

to

unit,

control,

external/32

I

at

together)

every

follows:

2

Jlsync:

There

is a

for

and video

interrupts,

MFP

main

bj-t

Mflz.

is

nemory

internal

such an

operation

Mllz and

gnd Hsync

Ìead/Write

60 Hz

or

50

tining

VSYNC

and

in

500

are

Signa]

crrip

Genàrator,

DMA,

MFP,

Memory

It arbitrates

devices

from

IlleEal

certain

sized

the

respond within

read

DTACK.

Mega Service

conditions

to

data

processor

from

Bus

and

qlbitration--

Controller,

Menory

the

Controller,

bus

interfering

condition

violated,

are

a word sized

in user

is

required tine

the

nemory

Ma¡rual

and

Glue

DMA

,

ROMs.

and

to

during

with

detectiq4--Glue

DMA transfers

other

each

such

register,

mode.

AIso occurs

linit.

Memory

the

2.2

decodes

addresses

Controller,

receives

It

synchronize

to

(see

DMA

asserts

as

writing

or

if a

For example,

Controller

Progranmable

signals

data

prevent

below)

Bus

to

'

Error

ROM,

system

device

the

does

Theory

generate

to

Sound

from the

transfer.

CPU and

(BERR)

writing

DeII¡ory

does

tries to

CPU

not

of

assert

Operation

DMA

if

byte

when

not

Main

Menory

Main

two

banks

sLot alrows

addressable.

menory

(2

Mega-byte

access

The

buffers, Menory

nostly

tine bits

up

Mbytes,

giving

current

converts

All

is

determines how

Controller

RAMs,

data

in

ROM,

wíth

R.{M is

or of a word

1 Megabit

of

organized

8 bits

at a tine.

and odd addresses

X 1

while in

two tines

BAM menory

Note:

These

The

Operating

nap:

the

are reset

versions

Menory

Controller--takes

to Row Address

RAIì|

accesses

progrannable

loads

during direct nernory

for

poner-up.

at

the Video Shifter

consists

each) of d¡manic RAM.

of L92 kbytes

to 128 Kbytes

components

of

controller,

optional

as

chips; in

the Mega

nemory,

the

segnents loaded

16

bit

Even nunbered

the Mega 2

4 there is

or 4 Mbytes.

000008-000800

000800-1FFFFF

200000-3FFFFF

first

8 bytes

vectors

which the

Systen is located

(192k).

Strobe

are controlled

up to 4

Megabytes

nuch Eernory

Ttre Memory

access

rn

ROM.

of

ne¡nory

the

a¡¡d

Glue. Tt¡e

systen

fron

words

refer

nay

and

addresses refer

to the low

there

a¡r additional

Systen nenory

low

bank

high

bank

of ROM are napped

68000 uses

in

two

addresses fron

(RAS)

by this Atari

is

and Column

nenory.

of

present

proprietary

and

Controller refreshes

with display

(DMA).

data,

of ROM addition,

All

nenory is

are:

Operating

disk into RAM.

be

accessed 16

I bits. RAIII

are 16

chips,

bank

(priveliged

(Mega

4 only)

into

on start-up.

lMeg

x

I

the address

Address

Tt¡e

Operating

prograns

gives

and

the

one

or

cartridge

directly

ROM,

System resides

RAM,

bits

RAM

at a

to the high

ís made

giving

of L6

addresses

ROM

chips,

access)

O-7.

chips

in

bus and

receives

or

(CAS).

which

System

Menory

dynanic

Strobe

chip,

the the

I

z

Glue--decodes

signals

hardware

to

registers

functions.

Direct

Kilobits/sec)

500 controllers.

hard

speed.

address

disk

For DlvlA

of

Controller

many

bytes)

data. The Controller

transferred

Mega

Service Manual

addresses for RAM

enable these devices

provide

to

See Glue

description

Direct Menory Access

menory

access is

and

The floppy

(or

other devices on the hard

to take

provided

high

speed

disks transfer

place,

where to tal<e data

is

set up

and the

(which

channel,

peripheral

entire block of data and to or

peripheral

the

from menory

without intervention

a¡rd ROM

(also

decodes

chip selects,

above.

).

to

(up

support both low

to 8

data via low

disk

Menory

the

fron

given

is

(the

before the

2.3

put

or

high

speed or low

a

comnand to send

must

size

operation

a¡rd asserts

addresses for

as well as nany

speed

Megabits/sec)

port)

speed

transfer

Controller

data

in

Sbit device

DMA

given

is

RAM,

speed, and how

or

given

be

to

starts)

by the CPU.

Theory

of Operation

output

nost

other

(25O

to

and the at high

the

DMA

the

receive

DMA

the is

then

exanple,

For

floppy

the ready Ci".l will

which

nenory

requesting

is

assert

reaa.

This

to lost

by

Glüe

read

was

byte

äpecified

to

high

At

ready

to

ACK

The

,r."."".ry

is

transfer

slowing

or

conúro1ler

asserti"á

signal

will

byte

the

set

fron

fJ-oppy

data

previously.

up

thè

number

are

on

speed

transfer

tel

to

Controller

DMA

ä.roty.

to

down

in a

will

ponO,

the

fron

floppy

ôr

sinilár.

FDRQ.

(hard

to

peripheral

tne

if the

the

transfer

signal

óue chip

tn"

Menory

Óontrotler

DMA

the

The

controller,

uyt"s

disk

or

can

68000

Data

tra¡¡sfer

has

The

port),

fron

store

is using

nay

sector

a

of

the

DItlA,

will

Controller,

Controller

DMA

and

been

floppy

there

DMA chip,

the

know

up

be

speed'

the

to

the

input

the

fron

Controller

the

read

the

-and

a¡rd

place

it

will

process

the

transferred'

initiates

a

is

the

ís

byte

bytes

l2

bus,

fron

every

difference:

DMA

avaÍlable

in

and

port

the

in

the wait

repeat

to

a

ar¡d

Controller

floppy

that

byte

Menory

then

wítl

Tra¡rsfers

transfer

as

Controller

or

internal

nust

DMA

the

without

nenory'

byte

is

signal

address

for the

until

from

by

byte

a

will

has been

De¡rory'

wait

being

68901

The

used.

are

MFp.

ñ;

receives

MFp

if the

ready

Iow) assert will

Th;8

interrupt

respond,

to

GIue

and

DTACK

read

The

derecr

HDINT),

(MONOMOÑI-,--R5232

parallef'óort

iine),'S'giO

ñoi árr while

MFp

timers,

RS232

used

port

handles

MFP

interrupt

Each

inputs

inlerrupt

an

is enatled,-MFPlyf

it

*nilI

put

and

lo

use

and

interrupts

ior

IRQs

operations

l/O

waitini

tñe

by

transnit

for

MFP

up

can

also

äre

input,

signals

."""tt

calculate

keyboard

for

Operating

r¡cr

vector

a

controlted

(including

gÚSV,

operation

an

and

InterruPt

16

to

nasked

be

directly

or

interrupt

(interrupt

number

address

the

by

display

MIDI

and

interrupts.

use

System

receive

Control

interrupts.

or

off

readable

generates

driven

be

witt

acknowledge

acknowledge).

data

the

on

the

CTS,

enable

data,

conplete.

to

for

clocks'

of

MFP

999,

(DE,

event

the

are:

and The

Currently

disabled

the

by

interrupt

an

low.

(Fco-2ìigh and

bus, interrupt

nonochrone

RI),

equals

MFP timers. CPU can

The

tining

all

by

CPU.

When

The

which

disk start

also

MFP

used

and

one

but

progrernning

the

When

internally,

is

CPU

the

vltlA

will

MFP

cPU

the

routine'

monitor

(FDINT

of

poll has

a¡rd

display

the

four

the

by

Mega

Service

ltlanual

2.4

Theory

OPeration

of

The

Menory graphics

video

Generator

controller,

output.

AUDIO/VIDEO

video

processing

subsysten

Glue,

unit

The audio

consists

graphics

a

(BImLiT)

subsysten

chip with a transistor

SUBSYSTEM

of

the video display nenory,

control chip

and a discrete

,

consists

output

anplifier.

of

(video

section

Progra.mnable

a

shifter),

to drive

the

a

the

Sound

There

nay

be used in

only

is

Ievels

112

is

one

used

for inverse/nornal

of intensity

colors

taken fron logical shifter palette;

either the

network

monochrome

separate

origin

Display

plane (see will

note

on or off. Thus,

power

lrd

to

output.

Display

located

Eenory

resolution)

nemory

half

to forn

page

boundary. The

the Menory

Systen

or infornation Shifter

wirl strean. rn color, of red,

bits

green,

Video

are 16

used in high resorution

color

row resorution,

palette

Shifter

registers

nay

4

video). Each

possible.

the

output the red,

there are three

proportion

node,

nemory

For

palette

description

$. The

=

the

is

of red,

blue,

given

a referred

and

pixel,

to by

of

video

green,

outputs for

the nu¡nber three

the voltage level

color

Video Display

part

outputs

palettes

of nain nenory

at the top left

is

configured as 1, 2,

one

planes

Kilobyte

32

interwoven

physical

Iogical

starting address of display

Controller's

Video

Base

Address

application. The Menory

into

the video

decode this infornation

nonochrone

are conbined fron

and blue.

Shifter 16

mode,

each bit represents

each

plane

Ín

be used

(actuarly,

palette

green,

the coror

getting

dispray menory

and

blue

each color. Each

possible

of

are sr¡nmed

give

to

are bypassed

Menory

with

corner

or

by 16 bit

plane

register

Controller

uits

at a tine,

generate

to

generate

to

the shifter.

in

high

onry bit so

resolution,

progr¡mmed

is

there

which is

infornation

levers

specified

output levels

through

I equal

a¡rd there is

physical

the

of the

(nigh,

4

words into

nediun,

starting

Eer¡ory is

by

will load

and the Video

a seriar

pixer

1

the comect level

0

of

AII 16

register

are

a¡¡d

for

are 8 x

I x I

displayed

from

betow). The

by

each

that

is

output is

is

Z to

a resistor

steps. In

screen

screen.

1ow

or

contiguous

at a 256 byte

placed

in

the Operating

display

dispray

on or off. rn

0 8

=

a

For

exanple, in

the

Video Shifter for

Video

nunber

those revers,

from

Mega

Shifter

(0-15),

(e.s.

palette

the

Service ManuaÌ 2.5

conbines

and takes the

0101=5,

then takes

low resolution

each

use color from

referenced

(16

word

pixels

bit 0 from

color

bit

by those four

from

1 fron

(4

ptanes)

displayed

each word

the

palette

plane

each

bits,

4 words

on the

to forn

referenced

register

and outputs

etc.

Theory

loaded

are

screen. Tt¡e

a four

a¡rd

!)

the coror

of Operation

into

bit

by that

outputs

G1ue

GIue

output,

causes

the

scanned

off

scan

go the

sigPal.

and

the

address

Memory

anâ

the

not

is

the

to

nonitor

In addition output display

active-only

control

nenory

The

synthesis,

"¡.

"ii"t

Hz to

which

tZJ

are

provides

monitor/RF output.

starting

counter

Controller

data

video

in a

monitor

or

tining

address

during

a¡¡d

shoutd

output

be

fron the

dilplayable

output

T.V.

to

signals

vertical

inputs

the

associated

lñto tne

changing

when

yM2149

sound

The clock

KHz,

míxed and

Progranmable

effects,

input

There are

sent

control

the

of

vertical

Video

loaded

Video

part

RF

a¡rd

Menory

from

Video

the color

ís

to the

Shifter.

Sound

and audio

2 MHz; the

three

nonitor

the

to

VSYNC

input

display blanking.

ShÍfter

into

that

the

Vídeo

Shifter

screen.

the

of

modulator.

horizontal

a¡rd

Controller

nentioned

Glue

video.

with

CMPCS

attributes

SYnthesizer

Generator

feedback

frequency

sound

channels

speaker.

Menory

the

to

nenory

DISPLAY

a display

Shifter.

during

VSYNC

These

sweep

DCYC

(color

in

the

(PSG)

(e.g.

output

Controller,

Menory

to be

reloaded

EI{ABLE

line

periods

and

signals

to

above,

there

strobes

nap select)

color

produces

alarns

response

fron

video

Controller

into

(DE)

tells

ís being

BLANK shuts

when

HSYNC

synchronize

the

both

display

are two

data

from

is

palettes.

nusic

key

a¡rd

the

is

chip,

range

30

pSG

The

relating to

This

Iocation

Single

transfer

associated

addition, registers,

filling,

seãd

transformations,

For

included

Service

Mega

printer

a

r.s

a destination

to

multiple

or

to destination.

with

the

more infornation,

in the

Manual

is also

used

port,

DMA device

word

merging

the

16 wõrd

the

blit can

pattern

etc.

Developer

also

filling,

in

disk

Atari

that

location

increments

There are

system

the

drive,

Blitter

moves

source

of

block

through

and

16

patterns ran a¡rd

used to

be

brush

please

refer

Kit.

2.6

various

for

RS232.

and

nenory

of

given

a

decrenents

possible logic operation

destination

a¡rd

three

perforn

line

to

operations

drawing,

user

the

f/O

fron a source

data

logic

provided

are

L6 bit

such

and

text

nanual

Theory of

functions

operation.

for

rules

data.

end-nask

as area

graphic

which

Operation

In

is

Real

Tine

Clock

Ttris

device has

data

Iines

signal lines

RESET

The

will

the CLKOIJII

JV

down.

are expressed with BCD

are

used to

RTCCS, RTCRD, RTCh¡R

line is

naín clock supplied to

also

be adjusted by a trimmer condenser

line

battery backup ca¡¡ be used

counters for

program

provided

a standard

the device

to reset

the devÍce is

clock signal

Battery Backup

with

Time

and Calendar

code. The

and access

which

the chip when

keep

to

buÍIt-in. Clock

lower four

address

the clock

generated

a

32.768

so that it

16.384 Xfrz.

of

the clock running

fron

a decoder. A

the system is reset.

l<hz

oscillator

will output

In

and data

through

which

through

addition, a

during

power

For nore

nanufacturer

detail,

(RICOH

please

part

number RP5C15)

refer

to

the application na¡rual

fron

the

Mega

Service Manual 2.7

Theory

of Operation

The

RGB a¡rd

MONOMQN

the

Iow).

The

types

th¡o

nonochrone.

input

possible

interface

of

presence

The

(when

â

disPlays

Video

Interface

are

of

nonochrone

are:

provided in the

nonochrone

a

nonitor

is connected,

Megas

ís detected

are it

a¡alog

will

by

be

Monochrome:

the

of resistor

RGB:

colors

output.

Monitor

Inputs:

û

single

Video

network

each

enitter

Shifter.

sums

have an

Hsync--TTL

Vsync--TIL

level,

Ievel,

Monochrone--digital

R,G,B--analog

Audio

-

ComPosite

-

General

-

Monochrome

-

Audio

-

Green

-

Plus

-

Horizontal

-

P-P,

12-Voll

Audio--1V.

Monitor

1 2 3

4

5

6

7-Red

I

9

foltower

outputs

emitter

negative, negative,

0-1.OV

1k ohn.

Out

SYnc

PurPose

Detedt

ln

Pullup

SYnc

a.nplifier

for each follower

P-P'

1.0V

P-P'

75

OutPut

driving

color.

a.mplifier

k ohn.

3.3

k ohn.

3.3

ohn.

J!

ohn.

10 - Blue 11

Monochrome

-

12

Vertical

-

13

Ground

-

Ttre

Sync

the output

three

drive

to

Mega Service

Manual

FIG.

MONITOR

2.8

8

PORT

Theory

Operation

of

rNPUT/oUTPUT

SUBSYSTEMS

Musical

The

integration

other

and Kilobaud)

ptog"an ilfornation

"rrd

(MIDI

thar

by

oUT

data

one

of

devices

as¡rnchronous

also

co.rsi"f'ãi

bit.

stoP

Connunication

to

in

l[ã-OóiO

MFP

the

via

chip

inverters

two

order

writeJ-to

6850

outside transistor

through

THRU

Musical

Instrunent

Mega

the

supports

takes

in

interrupt

inverters

trdo

the

on

allow

to

Instrument

nusiõ

with

fossessing

current

provided

is

optionat

the

bits

A.t.

8

place

response

controller.

on

the

side.

output

input

to

chaining

Connunication

Digital

Interface

sysnthesizers'

MIDI

loop

interfaces.

serial

two

by

ttlt¡t

preceded by

6850

a

via

interrupts

to

the

of

Ttre

tra¡rsnit

The

connector

nultiple

(MIDI)

sequencers'

communication

ports, MIDI

ntnu

port)

one

nCfe.

which

systen

start

The

are

is

side

input

signal

where

devices

allows

HiSh

speed

of

gUT

MIDI

.

a¡rd

bit

CPU

passed

interfaced

an

a¡rd

is routed

is called

it

on the

MIDI

drun boxes

(3L'25

keyboard

MIDI

and

specifies

followed

reads

fron

to the

LED/photo-

around

bus'

the

IN

and

the

II{IDI

Mega

Service

Js

J¡

Manual

Midi

1

-

2

-

3

-

4

-

5

-

Midi

1

-

2

-

3

-

4

-

5

-

Out

Transmit

THRU

Ground

Shield

LooP

THRU

Transmit

OUT

ln

Not Not Not Connected

lN

LooP

Connected Connected

Receive

Return

LooP

FIG.

MIDI

2.9

Return

PORTS

Data

Return

Data

9

Theory

OPer'ttion

of

Intelligent Keyboard

keyboard

The

nouse data,

of-day data

requests by the

6850 device

Microconputer Unit.

ROM are self-test diagnostics which are

whenever the

by the CPU.

interrupts

The 2 Button Mouse is

joystick

(year,

The MC6850 is read

which are

trarismits

data,

month, day,

CPU. Comnunication is

a¡rd

RESET

the keyboard assenbly by the

on

The HD6301 has internal RAM

connand

passed

characteristics: a resolution of

10 inches/second

joystick/nouse

Ieft

button.

button

four

directions

is

The right

wired to the second

and a

port

(up,

has inputs

button

down, etc. ) and

v

nake/break

key scan codes,

in response

hour, minute,

controlled

is

sent over

a¡¡d written to

to

a¡r opto-mechanical

naxinum

Mouse/Joystick

1

-

2

-

3 - Left/YA 4 - Right/YB 5

-

6

-

7-

I

-

9

-

CPU by Èhe

the

100

counts/inch,

pulse phase

for

up, down,

equals the

joystick

Up/XB

Down/XA

Not

Fire/Left

+sVDC

Ground

Joyl

port

one trigger.

Connected

Bulton

Fire/Right

to external

the serial connunication

joystick

Bulton

ASCII

events, and

second)

on the

lMHz

and

perforned

by the CPU in response to

MFP interrupt

device with the

a

error of

in response

nain

board by

8 bit

RoM. Included in

poh'er-up

at

controller.

following

mæ<imun

velocity of

percent.

50

left, ríght, right

trigger, a.nd the

joystick

trigger.

The

3

codes,

tine-

to

a

HD6301

and

line

The

button,

left

has

Mega

Service Manual

Joystick

1-up

2

Down

-

3 - Lefl 4

Right

-

Reserved

5

-

Fire

6

-

7-

+SVDC

8

Ground

-

Not

9

-

FIG.

MOusE/JoY

Button

Connected

10

PoRT

2.ro

Theory

Operation

of

Parallel

Interface

parallel

The

printer

centronics

Data

Centronics

on

ohn resistor

read

chip

interface,

STROBE

and strobe

printers

the data lines

port

Ttre

directly

select.

port

but

BUSY

and

signals

are compatible

should

pull-up

can

on the

programned

be

by the CPU,

prinarily

is

can also

are

supported. BUSY

are output

not

exceed 2.3 mA.

printer

to

with

intended

be used as a

by the YM2149

with

this

(TtrÍs

side.

)

input

be

Gtue

doing

or output.

address

as

general

is read

port.

a Centronics

purpose

by the MFp

psc

chíp.

The

current

corresponds

The

PSG

decode

to

r/0

Not

loading

to

a

chip

provide

type

port.

chip.

all

2.2k

is

Mega

Service Manual

Printer

1

STROBE

ç

-

2-Dala0

Output

3-Data1

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?5 .r¡

2f

16

rr 16

!5

19

4-Dala2

5-Data3

10

Not

6-Data4 7-Data5

8-Dala6 9-Dala7

11 12-17

18-25

-

Connected

BUSY

Not

-

Ground

-

lnput

Connected

FIG. 11

PRINTER PORT

2.17

Theory

of Operation

RS232C Interface

RS232C

The

handshake control

five

with

Ready are

and

(Universal

data

output Detect are

Ring

Synchronous/Asynchronous

transmission

divided by the clock

second

+/-

for receiver

supported.

are

I2v. supply

interface

by the

input to the

and

tiner

D

and

meet the

provides

signals:

PSG chip;

asynchronous

Reguest to

Clear to

chip.

MFP

Receiver/Tra¡rsnitter)

reception.

(pin

16) output

transnitter.

The

Data

f488 tine drivers

EIA

RS232C

standard

Send,

2.4576

the

of

rate of

and

serial

a¡rd

Send

Carrier

Data

contains

MFP

The

MHz clock

to

MFP

50

1489

to

provide

19200

to

line receivers

for electrical

connt¡¡¡ication

Terninal

Data

Detect,

USART

a

the

handles

MFP

bits

is

basic

per

which

with

interface.

\

Mega Service

Manuaf

Modem

1

Protective

-

Transmitted

2

-

Received Data

3

-

4

Requesl

-

5 - Clear

Not Connected

6

-

7 - Signal

Data

8

-

9-19

-

Ground

Data

to

Send

lo Send

Ground

RePeat

Carrier

Not Connected

FIG.

RS232

2.L2

T2

PoRT

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20

-

21

-

22

-

23-25

Terminal Ready

Data Not Connected Ring lndicator

Not

-

Theory of

'¡

2t

Connected

Operation

Disk Drive

Interface

The Mega

lrJestern

Digital

conputers

L772) and

have

a

logic for

built-in floppy

selecting

double sided drives. The Mega has one built-in

provision

Controller outputs

through

Iine, via

comnands, such as

passes

and

Systen,

CPU

when the operation

overhead of disk I/0.

for

one external disk drive. The hlestern Digital WDt772

services both drives. Drive

on the

the

above,

YM2149 PSG

DMA

Controller,

MFP interrupt

the

seek,

data to the

for

details

chip. The CPU reads

Tl:e 1772

controller. Tl:re L772

fornat

DMA Controller

is

conplete.

track,

on DMA

and side selection

Ínterrupts

write

(see

DMA

tra¡rsfer).

The

CPU

is

disk controller

up to

floppy disk

a¡rd writes

the CPU on

sector,

trr¡o single

accepts

read

drive a¡rd

is

done

to the

the

high

sector,

controller under

The L772 ínbemupts the

freed fron

nuch

of the

(a

or

by

L772

INTR

level

etc.

Main

Mega

Service Manual

I

Floppy

2-Side0Select

3

4 - lndex

5-Drive0Select

6-DrivelSelect

7 - Logic

I

9 - Direction

10

tlsk

1 - Read Dala

Logic Ground

-

Motor

Step

Pulse

Ground

On

FrG.

EXTERNAL

FLOPPY

2.13 Theory of Operation

11

Write Data

-

12

Write

Track

Write

Gale 00

Protecl

ln

L3

PORT

13

14

-

hard

The

controller;

is sent

board

a¡rd

Interface)

l,Jriting

to external

accept

DMA chip acknowledge

Memory

to

go

low and

data,

Cóntroller

device.

Controller.

DMA

disk

the

command

drive

hard

conna¡¡ds

paraneter

the externâI

to

CAl

fJhen

HDRQ will

that

respond

is on the

data

nust

feeds

Transfers

can

Port;

Hard

interface disk via an

block.

controller

go

high.

is available,

data

driven

be

within

data

place

take

Interface

Disk

is

controller

SCSI-like

Data

causes

DMA tra¡¡sfers

high by

2!0

or

bus

to

HDCS

the

nanoseconds

been

has

or accepts

to

up

at

provided through

is off-board

(SnaII

is transferred

(Hard

are

the

or

external

1 Mbyte/second.

Conputer

Disk

controlled

device

controller.

with

fron the bus-

read

data

via

Chip

is

ACK

fron the

DMA

the

and is

System

DMA.

Se]ect)

the

by

ready to

(}ow)

The

to

The

DMA

Mega

Service

a

Manual

Disk

Had

1-Data0

2-Dala1

3-Data2

4-Data3

5-Data4 6-Data5 7-Data6 8-Data7

Chip

9

-

lnterruPt

10

-

11 - Ground

Reset

1

2

-

EXTERNAL

Select

Request

FIG. 14

HARD DISK

2.r4

PORT

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13

Ground

-

Acknowledge

14

-

'15

Ground

-

A1

16

-

17

Ground

-

18

Read/Write

-

19

Data

-

Theory of

Request

Operation

SYSTEM

STARTUP

After

a

executÍng at

(GIue

000004 FEFFFF).

maps

8 bytes of ROM

points

The following

1. Perforn

2. Read is a

cartridge tal<es over here). If not,

Check for

3. written), initialÍze

running

it

was a warm start.

Initialize

4.

Initialize

5.

If not

6.

Set up operating system variables in RAM.

7.

8.

Set up exception

RESET

the address

to the start

the

"nagic

(power-up

pointed

FC0000-J

at

of the operating

sequence is

reset instruction

a

longword

at cartridge

nunber",

or reset

execute fron

a warn start

the nenory

the application which

PSG

the

color

h,arn start, zero De[¡ory.

a

chip, deselect

palettes

vectors.

button) the

to by

then executed:

locations

into

the addresses

(outputs

address

systen code in ROM

the cartridge

continue.

(see

if RAM locations

running

was

disk drives.

a¡rd set screen

68000 will

4-J, which is RoM

reset

a

F40000. If

controller,

pulse).

before

address.

0-7).

vrere

Location

(FCOOOO-

the

data

(diagnostic

previ.ously

and continue

the reset if

start

read

Initialize MFP.

9.

10.

Set screen

11. Attempt

progran

The 68000 has a feature calted

place when the CPU detects an emor

instrtrctions

vector

routine

the

occurrences

general purpose

on operating

exception

Mega

when an Ínterrupt or bus error is indicated

are executed.

(address

pointed

operating system.

(interrupts

the screen

systen).

which occurred.

Service

ManuaL 2.15 Theory

resolutÍon.

to boot

if

succeeded.

to a

to by

floppy;

SYSTEM

An exception

routine)

the vector. E:<ception vectors

Those exceptions whích

being legitimate) have

routine which wiII

(nushroon

clouds in

The number of

attenpt to boot

ERRORS

exception

internally,

wiII cause the CPU to fetch a

fron

RAM

and start

display some

older versions of disk loaded

bonbs equals the

hard

processing,

by external

when certain

or

processing

are

not have legitimate

do

vectors

nunber

which takes

initialized

pointing

of bonbs

nunber

of Operation

disk;

logic, types of

at the

to a

showing

of the

run

or

by

nay or ¡nay

files

System

from disk wiII cause the

errors

Verify the diskette and

computer.

not

be

system to crash,

drive before

disk

recoverable.

necessitating

attempting

Errors

to repair

in

loading

reset.

a

the

NUMBER OF BOMBS

(No.

26,28,30, ana 64-79 wiII

2 Bus

]

Error.

Address Error. Processor attenpted

AND MEANINGS

Glue asserted bus error

sized data on an odd

IIIegaI or

Zero

5

Chk

6

this,

Trapv

7

Privilege Víolation. CPU

B

location in

Trace. If

9

execute

sofuware.

Instruction.

RAM which nas not a

Divide. Processor was asked

Instruction. This is a

it nust

install

Instruction.

supervisor

trace

bit

this exception after every

10 Line 1010 Ernulator.

Provided to allow user to

11 Line 1111 Emu1ator. See

12-23 Unassigned, shouLd

24

Spurious

25-3L Autovector

should

32-63

TRAP

ion

64-lg MFP

BO-255 User

Interrupt.

no

have

Instruction.

processing.

interrupts.

occurrence.

not bomb, as

address.

Processor fetched an

legal instruction.

to

legal instruction,

handler.

a

instruction.

Chk

See

was in user

address space.

is

be

Bus

The CPU read

in

set

CPU read

the

pattern

emulate

Line 1010

no

occurrence.

error

Even nunbered

during

instruction

they are

CPU detected an error.

or

to access word or

legitinate.

long word

instruction from

perforn

mode, tried to

status

division by zeto.

a

if

software uses

access

register, the CPU will

instruction. Used to debug

1010 as an

his own

Emulator.

instructions.

interrupt

vectors are used, others

which forced except-

instruction.

processing.

)

ROM

a

Note: If

Mega

Service

you

have an emor

possible

1- The 2- The

the 4O-folder

can be used to

No ha¡rdles left or

3-

Manual

errors are:

file in total

number of

bad.

as

"T0S

in

the sysLem

nessage such

progress

is

folders

linit. However, there

extend this

too

2.L6

limitation on

nany

open

ERROR

is

a

then the

35",

has

exceeded

program

folders.

files.

Theory of Operation

which

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THREE

Ttris

software,

repair

used if

when

below.

Since

it

shouldn't

problens

give

down

troubleshooting

68000

consideration;

little

component sub-assembly. Many

naybe

section

and test

Mega/ST

the

possible.

running

a

systematic

problen

a

processor

the cartridge,

level

the

be expected

pinpoint

or

due

tine can be

level

socketed,

naking

conputer

The following

computer:

i

Atari

i

Atari

r

Atari

I

Mega/ST

I

Mega

*

RS232

t

MIDI Loop-Back

ì

Mega/ST

t

Diskettes

I

RS232

pertains

procedures computers.

If

the unit

of

to the test

used to verify

Tt¡e

diagnostic cartridge

gives

see

conplexity

that this docunent

the causes; rather,

approach which

to Íts nost

systems

nay

be helpful. Economics

to the

low

justified

of

it

the

may be

¡nore

when

a

likely

cost

in

expensive

verification

TEST EQUIPMEI.¡T

equipnent will

SCl224 RGB Monitor

SM124

SF354 or

Expansion Test

Loop-Back

ternirral

Monochrone

SF314

Floppy Disk

Port Test Fixture

Fixture

Connector

Cable

Test

Diagnostic

(2)

(or

Mega in

equipment, diagnostic

correct operation and

no

rrTroubleshooting

in

display

the Mega/ST

can

or

systen is

cover all

the intent

technician

can use to narrolt

source. Experience

is

assumed. Knowledge

witl

be arì ínportant

of the

troubleshooting

cheaper to

and

be needed

Monitor

Cartridge

Mega/ST

(and

critical) cotrponents

replacenent

to test the Mega/ST

(or

sinilar)

(or

Drive

(Mega

tff52

enulator node)

conputer line,

exchange the

siniJ-ar)

only)

(Revision

should be

R5232

a Dead

possible

here is

of the

down

faster.

to the

4.0)

output

Unit'r

high,

to

in

entire

troubleshoot

Mega

Service Manual

In

addition,

the following

repair

and

r

0scilloscope

*

Digital Multimeter,

*

Snall

*

Spare Parts

Ha¡rd

failed

(100MHz

Tool,

itens

computers:

Recconmended)

1l

FS

& Soldering

3.1

(or

will

better)

lron

be necessary

Testing

to

TEST CONFIGI.JRATION

With the

(IMPORTAI.IT--if

BE SURE

Connect

port,

plugged

cornputer

and

nonitor

few seconds the

skip

THE

cables

and

in so that,

MIDI

into the

Power on the down to

next section

power

CARTRIDGE

joystick

ports,

loopback

"

"Troubleshooting

If the unit

it should

diagnostic;

and will send

diagnostic.

be disconnected

otherwise,

nessages which

In the event

pclwered

determining

taken,

compu+,er

no display

a¡¡d

the

such as

to verify

is working.

switch

cartridge

the

INSTALLED

IS

fron test

/

fixture

nouse

if the

cables

the

connectors

nonitor

output

unit. Some

nenu screen

Mega/ST

Diagnostic

is being used

the

TROIJBLESHOOTING

the

that

appears,

problen.

checking

the

This assr¡nes

the

unit

does

Ínstall

not

off,

into the

ports.

fixture

would

into their

(a

tests

should

Cartridge

Dead Unitrr.

a

a terninal

as

fron the

nay think

host

will act

A

systen

this

LED in the

powered

is

Diagnostic

have

WITH

The

ioystick

ports

not be

the

plastic

the

THE CHIPS

hard

disk

directly

were

crossed.

ports.

nonochro¡ne can

run autonatícally;

be

will

If

below.

",

the

appear.

for a

host before using

soneone

keystrokes

like

DEAD UNIÎ

is correctly

is the

elementary

and

procedure

forward

naking sure

left corner

Cartridge

enclosure,

FACINC

port,

cables

parallel

should

facing the

PIug the PIug

the

be used

screen appeArs,

instead)

not, read

If

host computer,

is logging

input to the

configured

use

to

steps

have

the

nonitor

DOIW)

R5232

color

in

the

oD,

and

for

been

the

of

.

be

a

1. Connect a test

emulator

cable

(IJ.U.T.

should connect

(serial

(sround)

bits of data, for

the

Insert the

the unit.

display of

computer.

iroubleshoot. for information on

If no activity

(2)

with

Mega

Service

dumb terninal

You can

).

program--see

in) of the

to

1 stop bit,

VT)2 enulator).

If

the terninal,

The terminal

7.

Diagnostic

the

If not, the

Refer

using

is

page.

to

use an

owner's

the

(serial

2

terminal,

parity

no

Cartridge

use

conputer

to

the cartrÍdge.

on

seen

3.2

RS232

the

Mega/ST

nanual

running the

for out) vice versa.

a¡rd

should

be set up

(this

into the U.U.T.,

Cartridge

diagnostic

the

have to be

will

"Diagnostic

the

RS232

port

setting

the unit

of

l/T52

up

of the U.U.T

Connect

for

is

the

messages

9600

default

8¡¡d

appear

to troubleshoot

disassenbled

Cartridge"

display,

or

under

terminal

tÆ52.

pi.n

to

bps,

condition

power

on

below

continue

Testing

The

3

7

I

on

the tire

to

2. Disassenble

exposed

a¡¡

Replace oscillator if necessary.

68000 CPU.

not,

(2)

on

observing

(see

oscilloscope,

the CPU

doubte bus error,

input

pín

should be

conponent is malfunctioning

the conputer

Section 4,

verify

It

should be a

is halted. The

of the tn¡o

22

high

inverters

of the CPU

always.

so that the

Disassenbly).

the SMHz clock

TIL

high. If so,

reasons may

bad CPU.

3)

(BERR)

If

there

a¡¡d

on

Tt¡en check

the

as the unÍt

Glue is

printed

Power up the conputer.

the

to

go

(1)

be:

Check

are

(1)

HALT line. Check

logic low

generating

Verify the clocks to GIue a¡rd Menory Controller

conponents

is

unable

responding

to verify then

read ROM or there is a

to

read or write

to a

or DMA Controller. The

The DMA

way

chip should

to check

possÍbilities,

second)

a

strongly

respond

(3)

other

although a

indicates

(if

socketed).

the CPU,

by

MFP

should respond to

FCS

to

than by elinination

hot CPU

a bad

by asserting RDY. There is

(too

hot

CPIJ.

If

still failing,

conponent wlr-leh is not

probably

an

to touch for nore

circuiÈ board is

Using

(pin

68000

bV observing signal

is

CPU

(HALT)

17

on ro

reset

bad

powered

I

pulses,

15).

of the

below. If

circuit,

(2)

on. It

some

by

the error.

replace

and

the

MFPCS

with DTACK.

of the other

the CPU

MFP

these

68901

no

two

than

If

3.

f'ron ROM

be toggling.

the CPU

(cartridge,

possibility Verify the output of the unit with

through the 1488 driver.

RS232.

connection

the cartridge

If

Verify also the output

nonitor,

for R,

will be

check

does

output

check the outputs to the sunnirrg

G, a¡¡d

possible.

input

the

not

read a low on this signal on

on the Video Shifter.

If

the

is unreadable,

is not halted, it

if installed)

(If

not, replace CPU. ) At this

that both

looks

all to the

B. Note

the video

good,

terninai.

that

If using nonochrone,

to the

Video Shifter

there

is

should be reading instructions

and data a¡¡d address lines will

RS232

and

MFP

installed. If

Note

there nay be sonething

of the

(pin

chip

data

+

that

a¡rd

Video Shifter.

if BLANK is not

check output

power-up,

MFP,

29, M0N0M0N. Note

is outputti.ng a signal, but

probably

problen

a

cartridge should be used to diagnose this

terminal

as a

display

device.

point,

subsystems are failing.

8)

while

is

being sent. trace it

12v. is required for

-

resistors

going

Ít will

there

powering

wrong with the

If

(if

high, no

that

on the

using an RGB

external)

picture

30.

if

the CPU

cause

picture

the

with screen RArY. The

problen,

with

the

is

AIso

RS232

the

RGB

Mega

Service Manual

3.3

Testing

MEGA/ST

DIAGNOSTIC CARTRIDGE

The

diagnostic cartridge

conponent failures

several

earlier

revisions;

versions

Guide. This section

in

the conputers

this docunent

should

refer to the appropriate

gives

a brief

of each test, error codes

recommendations

The

particular,

appear,

before the

background in nonochrone)

diagnostic

the

a¡rd the screen will appear scrambled

menu is

testing, with a

Kbytes of RAIü is tested on

error wiII be

RAM is failing,

execution will

progra¡n

The

screen will be displayed

If

connect

will continue to test

keyboard fails, it will

the

terninal to the

a

for keystrokes fron

repaír.

on

program perforns

nessage

"Testing

printed.

message indicating

printed

fail

to the

screen nay not be

Lhe

because there

(the

R5232

RS232

the

Power-up

The screen will

if

a¡r emor occurs

power-up;

R5232

screen

port.

device.

is used to detect a¡rd isolate

(52O/LO4O

refers to

guide

pass/fail

or

several tests on

MFP, GIue tining,

the

if

device.

is no

stack

RAM and

¡nay turn

inactivated. The

be

The

and Mega). There

revision

4.0. Users of

Troubleshooting

are

to use with a description

criteria, and

power-up.

In

Video will

for a few

turn in

red

the

seconds

(dark

initial

failure. The lowest

locatíon fails,

a

It is

assumed that

readable

or

print

system variables.

emors, but

red).

diagnostic

a¡¡d

Repair RAM.

user nust

progra¡n

the

if

program

no

looks

2

If

the display

used.

screen.

test title and

anount of

menu

corresponding to those tests, and then the

All nessages

The normaL

revision nunber

RAM

and

below that.

is

unreadable,

printed

are

Test Menu

screen will be dark blue

keyboard

To

controller

select tests, the user types the

to the

are displayed at the

iterations of the test or tests chosen ca¡r be

nunber

of cycles

cause the test sequence to

before

sone tests before

total

Mega

Service

completion,

numbers of cycles will be

Manual

just

before typing RETURN. Typing a zeto will

run continuously. To

hit the

the

test

escape

stops). As

3.4

key

RS232

the

R5232

terminal should be

port

as

weII

as the

with white letters. The

top,

with the

revision below, and a test

keys

return key. Many

run

by typing

in

stop a cycle

(there

each cycle conpletes, the

displayed

nay

be sone delay

on the screen.

Testing

the

in

MENU

MAIN

Mega

nnu

4u

RAI{

R

Keyboard

K

Audio

A

Fioppy

F

Graphics

G

ReaI-tine

L

Expansion

X

Run

0

iun

z

ST

and

o

Keyboard

Test

Oisk

chiP

clock

connector

Tests

AII

rnternal

Field

1987,

0 M T P

(Blitter)

tests

Service

Atari

Diagnostic

CorPoration--

revisioi-V----6O

ROltls

0'S'

MIDI

Timing

Printer/JoY

(R,o'c'K'A'T'L'G)

Ports

n"

Test

0S

c

S

D H

Rev'

Version

CoIor

Serial

Port

DMA

resolution

High

4'0

Port

2

USA

NTSO

Exanine/ModifY

E

B V

?

Enter

RS2l2

Set

iãÀgr"

Help

letter(s),

Pressing

decreases

Pressing

cartridge

After

status

space

arrA

bar

If

before

the either will

rhe

completion

current

continuini

be

"

keysr"oL"

nenory

rate

iia"o

outPut--5o/6o

and

up

the

it.

or

'?'

functions.

test

a er"ãr-".po"t,

return

to

nultiple

tests

test,

"or,"id"iabte

i"-ããlãðt"0.

REIURN

the

or to

series

the

increases

HELP

arrovJ

are

pres"ins-ihã

by

sequen"å

the

returning

or

delay

Hz

ons

e.

tion

quires disassemblY)

ishted,

hrough

seleðtion

tests.

or

e

brings

key

tests

of

any,

if

nenu'

selected'

"iff

to

Uãfore

iup-lã

i

will

These

requires

hardware

baud

pressing

it'

conpletes'

will

the

tey.

BéC

hali,

nenu'

the

minutes

highlighted

be

should

the

test

the

tests

the

all

sequences

Selection

registers'

the

on

rate

brief

a

up

displayed'

be

sequence

ttte

Át

with

In

current

test

with

be

Present

exPansÍon

If

'

check

wirl

except

through

enables

'E'

RS232

down

the

synopsis

pass/fail

the

Press

be

can

conpletion

options

the

cases

some

conpletes

of

meg

4

if

The

RAM'

these

in

test

these

for

RAM'

the

'B'

Port'

arrovr¡

the

of

the

halted

of of

there

and

)

Mega

Service

Manual

3.5

Testing

RAM TEST

Sumnary of

Tests

RAM is tested

64t¡, a¡rd

fron

0s, a counting

counting

counÈing

buffer

RAM

pattern (data=conplenent

pattern

into

the current

new

to a

until the top of

boundaries

of

each

is

64t Utoct.

in to top.

64t

pattern

is copied

area,

RAM

checked

three stages:

verifies

by writÍng

If an error occurs,

the address, data

In

E.g.: units

"

having nore than one ba¡rk

well as the bit

agree.

address as

correct chip.

the addresses and banks

O-7ffff

Soooo-rrrrr

written,

R2 45603E W:603E

The following table

520

bank 0

100000'lfffff

200000-3fffff

(A

bit x 16

is

bank

chips--256k

=

a

16 Mbit

16 bit wide

x 16

=

2 Mbytes.)

or

The test

(data=low

word of

fron the top

J2

Kbytes

the

of pattern,

is reached.

unique

the error

read, and the bits which did

data

R:613c bad bits:

position

gives

for

various

1040

bank

group

UUit or

4

Vlega

0

bank

1

barrk 0

bank

of RAMs.

JL2k

2 kbytes,

low

patterns

used

the address)

of address

botton of a

and

video

RAM, then shifts video

and

niddle

are: all ls, all

low

repeats

(up

reverse

'

word).

Kbyte

J2

the test,

Finally, addressing at 64t

pattern

is displayed, followed by

code

(i.e.,

nust be used to find the

a

models:

2

0

A bank

bytes--or

in last 216

bytes

1,8".

1040ST, MEGA4)

correspondence between

Mega

4

bank 0

0

bank bank 0

bank 1

nay

consist

of 256k

lMbit chips--lMbit

to

The

not

the

RAM ERROR CODES

Except where

corresponding to the

R0--1ow nenory failed while setting

Rl--failed walking

R2--failed

RJ--failed

address

64t< boundary

noted,

indicated bit(s).

1s

or 0s.

(counting pattern)

Controller.

Mega

n4--failed

Service

while displaying area

Manual

repair by

up to

test.

Probable failure

tested

3.6

replacing the

run

test.

.

(video

RAM).

in

RAM

Memory

Testing

chip

ROM TEST

Ttris

systen to deternine

(PAL

or and the checksuns are against known

deternine there

128K

checksun expected for

may

ROltls;

The

2, French). error is set,

replace

or replace

New

incorporated

receive T0S revisions

will

be

COLOR TEST

This

displayed:

Each

band consists of 8

are represented, each

screen

a straight

involved,

The lines in

sca¡r

outputs on the Video Shifter for that color, and verify the values

of the resistors on the output. Too

the nonitor

levels, making it

The

green

sunmed together by a resistor network to

(G0,

intensity for

The

on.

put.

The

is

twice that of

sumned outputs. For exanple,

Rl and R2 on

anplifier, this resistor in

later versions of the video shifter

which has

to

signal

1 connected to a

BLANK

will be connected

test reads

the configuration

the version, tanguage/country,

NTSC).

AII bytes from

calculated.

value

good

if

be only

sone have

or bad.

two

test fails if

Incorrect

with

Six checksuns

ROMs

in

1

two

neg ROM'S).

the

checksun calculated does

the configuration

checksums are

displayed, replace

low ROM if

the

high ROM if

the

revisions of

any of H0, H1,

T0S

witl cause this

into the current version

before

necessary

to

verify

the

test verifies the Video

red,

green,

leve1s

blue, cyan, nagenta,

palette

(strips

should

líne

keystroke

operator

the display.

will cause

Video Shifter

G1, G2)

each color,

values of the

value of the

=

7 /8.

fron there to the video

and

network is incorporated into the full custon chip

part

nunber C101608

not

be discernable, but each color

across

the

screen).

intemupts

should see

If lines

nonitor

the

appear there are only

has three

and blue

(80,

depending

resistors

resistor

R2. This

this

allows us to

R0

signal then

line BLANK. Shifter with

pull-down

to diodes D9, D10, D11.

bytes

operating

checksuns for

system

These

of the operating

and

ROMs

are then

values are conpared

this version

are displayed,

the machine

(sone

machines have six

not natch

found

byte

indicated

the correspondÍng

any of

L0, L1,

or or

test to

(e.S.

nessage. If

by a

ROM. In

L2

showed an

H2

showed an error.

fail if

of the diagnostic. If

receiving

checksr¡¡ns

diagnostic revision,

the

yourself.

Shifter. Seven color ba¡rds are

yellow,

intensity. All

of

is

a vertical strip across the

Because

will that

cause

there

the display

are

nissing,

are

low

a brightness setting on

16 color

of the tight tining

to

gaps

no

check the three

not to distinguish between fine

four levels

outputs

for red

81, B2l. Each

give

on which of the outputs are

give

different weight to each out-

R0

at

on

is twice that of R1, which

get

8 equal steps on the

R1

and R2 off

,

passes

through a transistor

nonitor

(C101608).

or CO7O7I3

part

has

nunber CO259I4 will

resistor R144,10K,

being output.

(R0,

these

of

eight levels of

L/8, R0

=

connector.

Video shifter

1

connected

and signat

TV standard

read

although

the

Version

a two

ROM

error,

not

you

and white.

palettes

should

jitter.

missing

or

R1, R2),

triples

off,

NOTE :

have

line

to

an

it

be

is

to

Mega

Service

Manual

3.7

Testing

Symtons

and

fixes:

Missing

1.

anplifier.

staircase

is

there,

backward

found.

Prinary colors

2.

Replace the

Coarse

3.

tra¡rsition).

output

color.

Specks or

4.

if RAM

Shifter.

Wavering

5.

place

interrupts

interrupts,

registers

interrupt

every

(pin

inputs at

the

(to

tne

MFP.

prinary

pattern

trace

to the

color.

is

06

blue,

(eight

forward to the

Video Shifter,

present,

Video Shifter.

change

of one

in intensity

Replace

Video Shifter

of the three

lines on the screen.

has

display,

every

(if

it will

during a

request

mícroseconds

L26

tested

been

horizontal

tine.

processor

the

The

not

horizontal

(pin

(2

20). If additional

pins

22-29 should all

Ufp) source

for the

output

Check

Q7

levels

the

green,

is

video

intensity).

of until

secondaries

(not

a snooth or

color

a¡rd

processor

outputs

This

is

lines

can

good,

not

is required

have

tÍner

time).

scan

32).

interrupts

There should be an

display

lines)

occur, locate the

be

interrupts

of the transistor is red. Look for a

Q8

If the

connector,

faulty conponent

the

if

níssing or

dark to

for

look

for

be

a short

the appropriate

caused

by bad

replace the Video

occurring

nay be

in

getting

to handle additional

to change aII

Exanine

fron Display

high. If

is found,

no

replace the

signal

not,

trace

incorrect.

light

on the

RAM;

sane

the

extra

L6

color

MFP

the

interrupt

Enable

source:

external

is

KEYBOARD

first, and

keyboard.

is run.

comesponding

color). screen. the arrow

indicates

keyboard

microcomputer,

Mega

Service

NOTE: if the

will be

TEST

Two types

keyboard

low, causing

of test are

if this

If multiple tests

The operator

character

The key The

screen.

will

will also

mouse

Connect

flicker.

a short.

The self-test

nicrocomputer,

and scans

Mar¡ual

not

is

continual

run.

passes,

buttons a¡rd

the

checks comnunication

a screen

have been selected,

presses

the

on

be displayed

mouse

Any key clicks while the

and

the keyboard

connected,

intemupts.

The keyboard self-test

is displayed

keys and observes

screen

changes

four directions are also

nove

and

checks

RAM and ROM

for stuck

3.8

input to the 6850

the

representing

only the self-test

(reverses

in the in

between

lower half of the

any direction

¡nouse

the

in the

keys.

is

that

background

shown

a¡rd the

is noving

CPU and

keyboard

Testing

done

t'he

the

on

the

KEYBOARD ERROR

CODES

KO--stuck

test was

K1--Keyboard processor

keyboard

the

6850 is not functional.

K2--Keyboard

keyboard,

status. Replace

MIDI

through

is

correct. This

MFP

the

sent

MIDI

MO--Data

6850, through

input

key. A key

executing.

not responding.

and no

needs

to

status

on conpletion

the

TESTS

This

test

the cable)

chip. The LED

(not

all cables have

ERROR

CODES

not received.

the drivers,

of the 6850. Replace

closure

status

be

was returned

replaced

error. The

of

keyboard.

sends data

a¡rd reads

also

tests

in

the loopback

the LED).

Trace

was detected whire

A

connand

nas

within the

or the connunicatÍon

setf test

the

test,

out

the MIDI

fron

the input

the interrupt

the signal from

loopback

the defective

coûDand was

keyboard

the

port, (data

cable will

cable,

component.

the keyboard

sent to

the keyboard

allowed

channel

sent

and verifies

fron

the

68J0

brink

the

output

receivers

and

tine. Ttre

through

to the

an

error

loops

back

the data

through

as

data is

of

to the

self

the

M1--ldrite/Read

data nisnatch.

the data read. Replace

M2--Input

noisy

MJ--Input

noisy

M4--Input

frane

error.

signal

parity

error.

signal.

data

byte

overrun. The

was

not responding

read.

Ttre

data b'ritten

6850.

ga¿

6850 or bad driver

ga¿

6850 or bad driver

6850 received

Probable

to the

bad

interrupt

6850,

request.

was not

or receiver

the

causing

a byte before

can

also

be caused by

same as

the

Mega

Service Manua1

3.9

Testing

RS232

TESTS

t'irst the together tested.

nethod

tra¡rsnission

receiver

and

lines this

port, & there

connector.

likely that

R5232

Data transmission S0--Data

via

Sl--Daca

by the

Data

first, then

Data

is transnitted

is chips.

are output

test

as the

does

RS,232 device

are

If

the

ERRoR

CoDES

not received.

1488 to J6

nisnatch.

is checked transnissing?receiving

no

the

integrity of

S2--Input

Probable

frane

MFP failure.

RS232 control

loopback

using

connect,or),

interrupts.

at

perforned

by the

Interrupts

by the

not

PSG chip and

thoroughly

nay

load resisters

passes,

test

1488 or

f489

error:

Check signal

3

to

Data read was

the signal.

error.

Incorrect

lines

MF?

are

600,

a

300,

test

requÍre

in the serial

but the

are

9

cfrips

MFP

May be bad

tine between

are

then

tested

(which

the data

using a

LãOO...t92OO

1488

the

and

function of the

input on the

drive

the

voltage

unit

bad.

path:

via

MF?

1489.

not what

driver,

MFP.

capability

swings

fails

was sent.

receiver,

start

loopback is

bps.

f489 driver

and

MFP. Control

Note that

of

port

diagnostic

in

use,

8 to J6

and stop

are tied

polling

Data

of the

12 volts

it is

Check

MFP.

or

bits.

2

S3--Input

S4--Input

S5--No

S6--Tra¡rsmit

S7--Tra¡rsnit

S8--Receive

S9-'RI/DTR

SA--DCD/DTR

SB--RTS/CTS

Mega

Service

parity

Probable MFP

data overrun.

emor.

faÍIure.

byte.

IRQ. CPU did

GIue failure.

error.

MFP

error

intentionally

to cause

error

intentionally to

respond.

connection.

Manual

Input data

A byte

MFP failure or,

not detect

transnitter

interrupt.

interrupt,

an

interrupt.

cause

Signal

an

sent at

Signal

Sig¡al

10

3.

incomect

had

received before

was

interrupt

an

failed.

An

error

An

error

interrupt,

DTR

at

sent

at

sent

parity.

less like1y,

by the,MFP.

condition

MFP didn't

and

condition

the

and

is not detected

DTR

is not detected

RTS

CPU read

the

failure.

GIue

MFP

was ereated

respond.

h,as created

MFP did

RI.

at

DCD.

at

CTS'

at

Testing

or

not

AUDIO

TEST

Outputs

channels.

a low

One cycle

nissing, replace

output

the

the test

TIMING TESTS

fron

HSYNC,

tested. Tt¡e

RAIII

patterns

tests

error

the test

occur

the

printed.

TIMING TEST ERROR

TO--MFP

of the

nonitor

PSG

(these

These

the

chip wÍth an oscilloscope,

output

Ís being

tests

nenu.

a¡¡d the Menory Controller video

video display

verifies

a¡rd

nay flash

which

Dessage

check the bus timing

is

passes,

and the nessage will renain. If

RS232

not

port,

tiner

generate

error.

the

to high of each cha¡rnel

PSG

the

connector.

selected

both select the PSG).

run

are

Ttre MFP

sweep on each of the three

chip.

at

If

no output from

running

by

power-up

timers, the

perforned.

is

no sound is heard,

and trace the

printer

the

as well as

GIue

tining for

the

being selectable

display

redirects

test

that

the correct

on screen as this test is run. Tt¡ere

addresses are

for

printed

the

to the screen,

nessage

1s

erased.

display nenory

1772

the

then the test is run. If

and

If

not, a Bus Error

a terninal is

nessage

CODES

One

interrupt

an

or

not

will

nore

on counting down

be erased,

of the

four

but

tiners in the MFP did

sound

If

a

channel

verify the

signal

PSG,

port

verify

RS232

or

VSYNC a¡rd

counters are

throughout

generated.

are

PSG

chips. An

connected to

'rPass"

will be

is

to

Odd

two

will

Tl--Vertical

required

T2--Horízontal

required

T3--Display

generating

not

t4--Video

Sync.

tine

Sync. Glue

time

Enable. Glue is not

Counter Error. The nenory

the correct addresses

broken-up dÍsplay in

T5--PSG

T6--L772 Bus Error. The LlJ2

Mega

Service Manual

Bus Error. Ttre PSG

GIue is not

period.

interrupt.

an

sone or all display

generating

is not

generating

controller is not

for

the display. This

is

chip

chíp

3.11

defective.

is

defective.

vertical-

horizontal

DE

output

will

nodes.

sync

or

in

s¡mc

the IIIFP

generating

result fn

.-

ruu

f

Testing

in

the

is

a

lt)

DMA TESTS

\/o'

(2048

the

Four

port

sectors

test fixture via high speed

verified. Tt¡is test Ís

throughout the

DMA TEST ERROR CODES

DO--DMA

tined out.

GIue, or

processed

íf

the

with

causes

D1--DMA

counter error.

rarìge

Memory

by the

DMA Controller responds to

ACK.

Verify the

INTR output fron the

an

bytes)

repeated nany

RAM.

of

No DMA

occurred due

Controller, or the

MF?.

The failure can be

MF? by seeing that the HDII{T input

the nunber

incorrect. The Menory Controller or

D2--Data nisnatch

not

the sa¡De as the data sent.

problen persists,

the

emor.

opens a¡rd shorts.

7lJ2 is

D3--DMA not responding. DMA

resquest fron

FLOPPY DISK

loading the bus.

the external controller.

TESTS

Ttre

check the

A

third

controller

of data

MFP.

received fron

data

Replace

possibility

are h¡ritten to the RAM

DMA,

tines

then

read

for RAIII

back a¡rd

addresses

to faulty DMA Controller,

HDII{Î interrupt was not

isolated

HDRQ fron

the test fixture

by seeing

of bytes transferred was

DMA

Controller is bad.

port

DMA

the

DMA

the

data lines

is

could not respond

Replace

Controller. If

to the

port

that a defective

to a data

DMA

the

chip.

on

was

for

The Floppy Main Menu

Floppy

(I{ARNING

1)

disk drive

Quick

--

Test

2) Read Alignnent Disk

Disk

3)

4

5)

6)

7) In

1.

)

Interchange

oist<

E;<erciser

Check copy

Test

Speed

InstaII

single test

Quick reads

a¡rd

test.

tracks

rvrites

overwritten.

drives are online and

assure that the drive are correctly tested, the

operator should

test. Once the

will

and

size).

Mega

Service

Manual

routine

all choices

Test

protect

disk dríves

noder

For

0,

track

If

displayed on the nenu screen

be

(80-82)

disk

79

if

they are

(nenu

run,

2,6,7

of side 0.

write to the disk)

installed, fornats,

If double

1

verifies

and

installed,

double or

that side 0 was

checks to see what

single

writes, and

sided,

option 6) before calting the

the drives become

sided.

installed,

except

tracks

r¡enu is displayed showing seven options:

a

each

L,

and

of side

79

no

disks are

install

test is

(below

3.72

fornats

the

Testing

not

To

RAM

2.

Read

track.

Continuously reads

with an analog alignnent

input

a nunber, the default

by the

operator.

diskette.

If

"Return"

is

track 40.

track,

a

for checking

The

track

pressed

is

alignment

be read

to

nay

without entering

be

Interchangeability test. Checks to see

3.

disk drives each can be

Disk exerciser.

4.

on the disk

Copy Protect Tracks. Tests tracks 80-82,

5.

softrùare conpanies for

some

are cause

drives will

Test speed.

6.

for

for replacenent because sone

not

A nore

a¡r

write to these tracks.

The rotational speed of the drive

displayed on the screen

acceptable

lowest key is

InstaII

7.

If nore

floppy nenu will

range is

values

pressed.

disks.

than

not

measured are displayed.

Specify

one test

appear,

read

by the other

thorough disk test;

indefinite

period

protection).

copy

as the

196-204 nitliseconds. The híghest and

how nany and what type of disks to test.

is

selected

but the

Quick

autonatically.

FLOPPY TE.ST ERROR

No floppies connected--the

The

cable

pohrer,

or the

CODES

nay be

drive

controller

inproperly connected,

is faulty.

if diskettes

of tine.

period

The

from

the

Test

cannot

or the clrive

fron two

disk drive.

tests all

which are used

Not all

nanufacturers disk

sectors

failures

Ís tested and

rotation.

of

test stops

when any

nain nenu, the

will be selected

read

:Lndex

pulses.

has

by

The

no

F0--Drive

resLore

to drive. Verify Listen for the sound

diskette should

1772')

of the interrupt to the asserting light), check the is

selected.

F1,F2,Fl errors of

nessage now says

and displays

errortt.

Mega

Service

not

selected.

(seek

track 0).

to

the

open).

go

should

Iow.

7772. If

INTR.

If the drive

PSG chip.

selected, and

not, replace the

If

nore

a

Manual

Drive

light

of the

If

installed, but

was

Check cornection of cables,

front

the

on

head

seeking

this occurs,

all

so,

check

for

none, replace the

MFP,

verify

that

is not being selected

19

versions

liriting"

specific

3.

Pin 20 should

should

PSG.

emor

13

go

have

(or

failed attenpting

of the

an

drive

(the

slide

(pin

TRO

interrupt on

1772. Else trace

MF? responds be

the

go

low when drive

deleted.

been

reading or

nessage, €.8.,

formatting),

pourer

goes

on.

on the

23

The error

on

B

CRC

"F9

Testing

the

28

the

(no

is

A

F4--Seek

t,l:e

but

error.

1772

Verify that the

are

sent to the drÍve. Probable failure

the drive is

also suspect.

STEP,

MO,

and

DIRC

outputs

in

the L772,

fron

Fl--lirite

If during not,

F6--Read

supposed

diskette,

F7--DMA

DMA. Replace

FDRQ

high

reset not,

protected.

0K, verify

the test; if it is,

problem

the

compare

to be

disk drive, L772,

error.

whÍle running

with

each data byte

button

trace RESHI

still stuck, replace

F8--DI{A

F!--CRC

FA--Record

count

not fix

error. Replace

it, replace

error. The

Ehe 1772.

not found.

be

a bad diskette,

but not

not

drive

A).

Check the

that the ldP input

is

with the

error. Data read

written. Check in

DMA

Controller

DMA

the

could

Controller. If

the test. It

transfemed. If

a¡rd verify

to

diskette

The L772

B,

Ehe

its

E}r'e

DMA

the

or disk

drive

1772 is

that

source.

1772.

the Memory

could not read

or

write

and

protect

(L772 pin

the 1772 Is

then

drive.

disk

from

the

DMA Controller.

not respond

should nornally

(L772

MR

If MR

Controller,

Controller.

drive

L772. If

not

at

tab on the

2l) is

defective;

disk

was not

the following

to a

emor

nay

the test. fails

fault

persists,

be low

stuck high,

goes

13)

is

0K, but FDRQ

be bad,

a

sector

(likewise

diskette.

going

low

what was

order:

request

check

and

push

low.

for

go

the

If is

if

that does

else replace

header.

May

drive A

fails

if

B

Mega

FB--Lost

1772

passes,

also be

FC--Side

select

both

sides of the

to

be overwritten.

FD--Drive

Probably

Could

Soft Error

Hard Error

Service

Manual

data. Data

could tra¡rsfer

the tJl2 is

fault.

at

was transferred

to the

probably

emor--single sided

diskette, but writing

not ready.

a

bad disk drive. Verify

also be a faulty L772.

does not

=

fail failed

=

of the

fornat

!

The fornat/write/read

cause a failure

a second time.

second

retry.

following:

errors.

14

3.

to t}:e L772 faster

DMA

Controller. If DMA

bad.

The DII{A

drive. The test tried

side

operation

by checking

after 1 retry.

)

Unit

20 read

halt if

will errors, 20

than the

Port

Controller

to

1

caused side

timed-out.

another drive.

(If

doesn't

you

reach any

write errors or

Testing

test

could

write

0

PRII.ITER AND

JOYSTICK

PORT TF"STS

port

The

port on

outputs data on the

joystick

and

the test

fixture and reads

test fixture joystick

connecting the

reversed,

Po--Printer

what was written. Verify that

(pins

the RS232 test.

chip

-

selects are being activated

the

If J1l is

PSG.

P1--Busy input

data

or the

port

6-13) are toggling

is

PSG is

the data

(Joystick

good

by testing

the STROBE output Joystick 0 occurs, see amiving at

the test

fixture

test

ports.

parallel port,

to the

Joystick

in response

joystick

printer

PRTNTER/JoYSTTCK ERRoR CoDES

and

error.

If

probably

selected and

the

not being

lines toggle, verify

0)

error.

3

another conputer.

The

fron

handling

MFP

is not connected.

I

pín

22 fron

fixture may be bad. Verify

is

used to test

parallel port

The

back data.

which

ports.

to connands

ports

to the test

joystick

Data read fron the

the

when

the test

RI-DTR

and

The

is

The keyboard

from

tests will

data

DCD-DTR

selected.

and

not

outputting signals,

the

2ütlz

continuity.

pulled

is

up. Verify the test

If it is

input

the

to the

PSG

MFP is

is not

If

for

that. Othervise,

J5

11. If no signal at J5, with

paralle1 printer

the

writes

test

joystick

directed through

CPU. The

the

a latch

to

port

reads

cables

test

the the

fixture nust not be

fail.

printer

lines

port

on the

was

PSG

not

chip

is run. If not, run

errors occur, the

Check if

cLock

is

the chip

present.

If

replace it.

AIso verify

that

fixture

replace

0K,

not being

read,

the

or

functioning, or

P0

the

look

error also

for

a signal

another conputer.

JO--Joystick

Busy input

the

pins

Jl--Joystick

Busy

the

pins

Port

keyboard. If error

1,2,3,4

Port 1. The

input error occurs,

keyboard. If

1

,2,3,4

J2--Joystick time-out.

outputting data on the test fixture to the

detected

This

keyboard faílure,

faulty

by

error ca¡¡ be

test

this elininates

Mega

Service

Manual

keyboard input is not functioning. If

Ttre

0.

error occurs,

to ltZ

pins

keyboard input is not functioning. If

error

to ttZ

pins

Joystick

joystick

keyboard and sent to the CPU via the 68¡0.

the

caused by

keyboard-CPU connunication line, or a

fixture.

any

If

problen

3.r5

fix

persists,

12,10,9,8 respectively.

fix

persists,

J,5,4,1

printer port

the

with

first.

that

check continuity

first.

that

check continuity

respectívely.

inputs

and routing Ít via the

ports.

porter-up

keyboard-CPU

othervise,

otherwise,

rdere si¡rulated Joystick

failure

keyboard

replace

fron J11

replace

fron J11

inputs

(code

test

communication.

passes,

Testing

the

by

are

P0),

J3--Left

0therwise continuity

button

replace

from J10

input.

If Pl emor

keyboard.

the

6 to ltZ

occurs,

0n the

11.

fix

520ST,

that

first.

also check

J4--Right

button

Otherwise

continuity

HIGH RESOLUTION

If this test

message

a waits

received

the

is

displayed

for an

interrupt

(the

dÍsplay to

horizontal and

reverse every

will

is

correct,

nonitor

RGB

GRAPHICS

he

a¡rd

CHIP

This tests the

around and

appear

(G0-G13)

chip.

REAL-TIIúE CLOCK

A faulty

perform

on the screen.

but the

,

input.

replace

fron J10

MONITOR

is selected

operator

high

vertical

two seconds.

unplugs

the display

(BLiTTER)

abÍIity

logical operations

action

BLiTTER

Pl

If

the

emor

keyboard.

6 to JtZ

while a color

connect the

to

from the

connects the

MONOMON

nonochrone

resolution. lines, each

ltlhen the

nonochrone

the

should

of the

Ma¡ry different

for

may

cause

return

BITBLiT to

any emor

BUS

a

fix

occurs

0n the

nonochrone nonitor. The

input

,

520ST,

6.

monitor

to the

that

is

MFP, and when

nonitor),

first.

also check

connected,

changes

Ttre display screen shows

pixels

2

nonitor and

on the

error

is the sa¡ne:

ERROR.

in

width.

operator sees the display

nornal.

to

Eove blocks

data.

messages are

Ttre

screen

re-connects

of nenory

patterns

No

possible

replace the

CPU

the

The test saves

time, waits

etc.

have all

verify all

EXPANSION

This fixture test

software,

interrupt

and

the CPU are after

Three LEDs will

BGACK

expansion

floppy test are

toggling.

Mega

Service

one second,

registers.

CONNECTOR

test,

(the

top cover

fixture).

the

and

lines are tested

tested

the systen

(bus

grant connector

A lit LED

Manual

current

the

and

rolled over.

modeJ.s,

Mega

for

and shield

It tests the

renainder

with the

is

turned

remain

acknowledge).

run.

neans the

on and

lit:

is run

test

The LEDs sinply

time and

verifies

is repeated

The

requires the expansion

must be

expansion

by LEDs.

in

software.

LEDs.

BR

line

3.t6

Most of the

the

(bus

These should

and

is not changing.

and writes a

minutes, seconds,

that

date,

hours,

for a¡rother

renoved to

interface,

The data and

The

control

LEDs will

Inenu appears on the

request),

(2)

either

BG

go

off after

indicate that

install Èhe in

address busses

(bus grant)

DltIA test or

the

new

date to

test

part

by

lines fron

go

off

screen.

and

(1)

the

line is

Testing

The software

bus,

and

tests

interrupts.

three

groups

signals:

of

bus, address

data

The first

setting

one bit

lines. If an

displayed.

The second

across address

RAM

If an error

byte" or

on

create

and

the test

on

I'EX2

whether

The third test

interrupt

INT7.

expected,

errort',

ERROR

or

CODES

Ttris

occur

INITIALIZATION

11 RAM

when

data

test

high

error

test

bits

fixture to check

is found, the

external

the error

uses

requests.

If the

then a

ttEXl

QUICK

is a

running the

nessage Ís displayed:

INTJ errortt.

REFERENCE

brief

(Errors

is stuck.

line

L2 RAM disturbance.

location.

RAM

13

14- MMU error.

I5

.

RAM

addressing.

sizing

DTACK after

No

error.

T6-

writes

at a

and

tine, to

is found, the

writes an

O-1!, then

message

RAM emor,

occurred

in

circuitry

There

appropriate

sunmary

diagnostic.

occurring

Location

Wrong

Uppernost

is

location

RAM access.

check

RAM on the

for open

reads the

nessage

increnenting

across

address

for open or

external

"EX1

high byte"

low or

the

on the

are

external

three

interrupt

"EX3

all error

of

before

altered

the

by write

is being

address

faiLs.

test

or shorted

bad

"EXO

pattern

16-23 to

bits

shorted

is

address

RAM error'

printed,

high address.

test

interrupts:

does

not

INT3 error,

code

title and

to another

addressed.

fixture,

data

bit"

is

(0,1,2,...1

the

bits.

low

depending

fixture

Il.¡T3,

occur

menu appear)

IlfT5,

"EX4

which

5

when

INT5

nay

V*,

to

tr

rrirl-

6

LU

!

¡'')

u¡ò1

tJ

"¡4

i4

Mega Service

EXCEPTIONS

El--E5

not used

E6 Autovector E7 Spurious

Device

EB Internal E9 Bad

Instruction

EA Address

address

address.

or bad

.--EB

Bus error.

externally

Displays

Manual

(may

occur

error.

at any

IPLO

interrupt.

interrupted,

Exception

Fetch.

error. or

Tried

read or write

Usually

instruction

Generated

GJ-ue. Usually

by

address of

the

tine)

grounded

is

Bus

error

to

not

read

word

but did

(generated

this error

fetch.

internally

caused

the device

3.17

or 68000

during

by 68000).

exception

provide

instruction

an

or

preceded

is

by

being accessed.

is bad.

processing.

interrupt

vector.

from an odd

long word at

by a

by

device

the 68OOO

bus emor

not responding.

an odd

or

Testing

RAM

R0 Emor

execution.

Rl Error

R2 Address

line R3 Address R4 Error

KEYBOARD

K0

Stuck

K1 Keyboard KZ

Keyboard

MIDI

in

in RAM

low

chip.

nenory

error.

not

working.

error at 64k boundary.

during

key

video

controller is not responding. controller

M0 Data not received.

Ml Data received

M2 Data M3 M4 Data

RS232

input franing

Parity

error.

overrun. Byte was not read fron

byte

arrÍved.

is not

(first

Bad RAItl

RAM test. Bad

error.

chip

reports

what was sent.

2K),

or

error.

possibly

memory

RAM

chip.

the 68!0

affecting

controller.

before

program

Address

il

>

Data not received.

S0 51 Data received is not 52 Data input franing

Parity

53 54 Data

error.

overrun.

Byte

what was sent.

emor.

not read fron

was

byte arrived.

55 IRQ. Ttre MFP is not

receÍve.

Tra¡rsnitter

56

No interrupt

57

No

58

interrupt from receive

59 DTR--RI.

connector.

SA DTR--DCD. SB RTS--CTS.

DMA

D0 Time-out.

Dl DMA

count eror.

Controller

error--MFP.

fron

These signals are connected

Changing

Same as 59 Sa.ne as 59

DMA did not take

error.

generating

transnit error

error

DTB

does

for

these signals.

for

these signals.

place,

Not

aII bytes arrived. Possible

D3 DMA Controller not responding.

MF?

the

interrupts for

(MFP).

not

cause change in RI.

interrupt

or

before

the

by the loopback

not

detected.

Menory

Mega

Service

Manual

3.18

Testing

TIMING

MFP

T0

timers

T1 Vertical sync

Horizontal sync

T2 T3 Display Enable

failed.

timing

tining

Interrupt T4 Menory Controller T5 PSG

Bus

the data

T6 1J72 Bus

data bus

the

PRINTER

AND JOYSTICK

P0 Printer Pl Busy

(printer port

J0 JoysÈick J1 Joystick

Joystick

J2

Left button

J3

Right button

J4

FLOPPY

FO

DISK DRIVE

Drive offline.

test.

bus too

test.

port

port port

(keyboard

PSG

L772

too

error.

0 failed.

failed.

1

line failed.

line faired.

Not responding to

F1 Format error.

(Note:

now

specific

former

will

F2,F3 write and

say

"error

error

found.

failed.

video address

is

chip

long.

chíp

long.

PORTS

causing

is causing

input) failed.

controller)

read emors

writing"

)

counter

a bus error

timed-out.

restore

are deleted.

reading]

[or

failed .

(seek

and

ltt - ¡r--^\

4'^

a

i'

b

ö

by staying on

track 0).

The nessage

display the

wJ

'

F4 Seek emor. F5 ['irite

Data conpare.

,F6

DMA error.

n FB DMA count

F9 CRC error. FA Record

Lost data.

FB

FC Side select

FD Drive

Mega

Service

protected.

error

not

ready.

not

Manual

(Data

found.

error.

read

(Menory

Tined-out

not equal

Controller

perforning

3.r9

to data

counLer.

the command.

written.

)

Testing

Top Cover Removal:

SECTION FOUR

DISASSEMBLY/ASSEMBLY

MEGA/ST DISASSEII{BLY

1) Renove keyboard

2) Turn unit

Renove

l)

the top case

is

to be exposed,

renove

the disk

Turn

4) stightly fron

underneat its

renoved

Upper

Shie1d

1)

Straighten

located

2) Lift

be free from

Push

3)

shield out of the botton cover and

Disk Drive

Removal:

connector fron the

upside down.

the

screws fron

9

to the bottom. If

the square holes. These fasten

side of the

the

or the disk drive is

the three screws fron

drive Ín

place.

the unit upright.

the back,

left rear

easily.

Renoval:

the six twist tabs.

under the disk drive.

the shield up fron

anythings

in

l{hile

unplug the battery

corner.

the

lifting

back

rear.

round

Note

gentlely

the disk drive up while lifting

pull

top cover.

printed

cÍrcuit board

to be renoved,

ho1es. Ttrese hold

the

top cover up

connector fron

Now

the cover

can

that there ís

so

up the front of top

forward.

that

it will

also

be

one

Mega

1) Lift

Power

Supply Removal:

1)

2)

3)

Service

the disk drive

connector

Remove

Unplug

corner of the

Lift

ManuaÌ

and the

the

the wire

poh,er

the

2

slightly and unplug

ribbon

screws at

harness

poh,er

supply up out of the

cab]e.

front

supply.

corners

connector in

4.r Disassenbly/Assembly

of

main

power

the

power

the

assenbly.

harness

supply.

right front

Renoval of

If

1)

the

2) Renove the

botton

Lift

3)

main assenbly

power

supply

six

case.

the assembly

fron botto¡n

has not

renoval

studs

already

whÍch

from the

up

section

case:

been

to

secure

front and

renoved,

renove

the

it.

I/0 shield

then

pull

follow

the

to

fon¿ard.

Renoval

1) Straighten

2)

3)

of Shield

twist

Renove the

Note:

convenient

a¡rd

side

tabs away

Now

disk drive

if those

the

Lift

Printed

Fron

six

twist

tabs.

fron the

I/0 shield

najor conponents

the

that

configuration

may be

components

printed

circuit

It

back.

Board:

nay be

slightly.

necessary

are exposed,

Circuít

board

in the

for troubleshooting.

re-connected

needed.

are

assenbty

and

away

pull

to

this

keyboard

The

placed

off

fron botton

the

is a

to the

shield.

I'tega Service

Manual

4.2

Disassenbly/Assenbly

Mesa/ST

RE-ASSEMBLY

1) Place

2) Attach the

on

Place the assenbly

3)

4) Secure

PIuS

5) with tabs

etace

6)

Fasten the

7)

corners supply shield

insulation

top of

the

power

in

assenbly

with tno

I/0

Botton

I/0

in slots.

power

hold the scree,,

Plus disk drive

8)

go

under

Push

t)

the

10) A1ign tabs on

fit

place.

in

shield),

the battery

rear

left

shield over

top

panel

shield

Shield

on botton

to the

over

Ín lower

shield

supply

in lower

in

or by

power

corner

bottom shield

to the

connector

plastic

supply to the botton case at

screws.

place,

and

corìnector

Tttis

using a

renoving the shield.

ribbon cables

and

position

up

of the

nain

assenbly.

shield.

ports.

I/0

insulator

plastic

botton case with the 6 studs.

case.

position porr¡er

and

case.

be done with the

car¡

magnestized

drive over standoffs.

fron the

top shield.

with slots on top

Twist

Place

panel.

screwdriver

into

drive

opening

the tabs

Main Board

supply

front

both

power

(cables

located

shield

lock

to

in

and

Mega

11) Place the top cover

12) Turn over the assenbly

longer screhrs

drive.

It is strongly

plastic

in

there are

and

Service

Manuaf

to

no shorts to

reconnended

nalce

sure

over the

go

into

A h¡ORD OF

that

Shield.

assenbly.

replace

and

round holes

the

CATITION

the

screws.

9

to secure

that the conputer be

re-assenbly

the

4.3

was done correctly

The three

the disk

retested once

Disassembly/Assembly

SECTION

SYMPTOM

FIVE

CHECKLIST

This

their

troubleshooting

on

Troubleshooting

Sympton

DISPLAY

Black

White

Dots/bars

screen

on

color

One

Scra.nbled

T.V.

section

probable óauses.

nost

PROBLEMS

screen

nissing

screen

output

bad

gives

in this

Guide.

Probable

No

Shifter.

a

Video

Controller,

with

RAM,

diagnostic

video

signals

Glue,

cartridge.

Ir{odulator,

with

a

power

Dead

Shifter,

Menory

your

For

summary

nore

brief

docunent,

Cause

(check

See

LED),

TESTING

Unit".

Glue,

68000.

terninal

Controller,

cartridge.

sunner,

oscilloscope.

$rith

Menory

Contro1ler.

phase

oscilloscoPe.

of detail, of the

bad

section,

Menory

Use

connected

buffer,

locked

loop.

comnon

refer

problens and

the

to

Diagnostic

GIue chip,

"Troubleshooting

Controller,

diagnostic

RS2l2

via

Video Shifter.

Use

Trace

Shifter.

the

Video

section

Cartridge

Video

bad

DMA

cartridge

port.

Use

Check

diagnostic

signal

the

DISK

Disk won't

won't

Disk

Systen

Ioading

Mega Service

boot

PROBLEMS

Power

chip,

supply,

disk

DRIVE

if not,

spinning.

drive

disk

working,

diagnostic

the

fornat

crash

files

after

FDC(1772),

Diskette,

Menory

the

Controller.

âiagnostics

Controllèr,

drive.

Manua1 5.7

drive.

check

not,

If

or

check

DMA

disk

Menory

(1772),

FDC

if select

See

outputs.

PSG

check

external

an

try

Controller

DMA

cart.

Controller,

dríve,

Swap

check

to

Controlleri

Controller,

DMA

Listen

power

the

drive. and

disk

FDC

ß772),

diskette,

FDC

or

Synptom

light

goes

for

supply.

L772

drive.

DMA,

retry.

(L7721,

replace

Checklist

If

PSG

on'

Eotor

Swap

not

with

ot

Use

DMA

disk

Systons

Probable

Cause

KEYBOARD

Keys

won't

Keys won't

nouse

but

UIDI PROBLEIUS

No

data Bad

RS232

No

data Bad

PRII.ITER

No

output

Does

not

to

a specific

PROBLEMS

work Bad keyboard work Keyboard

does

PROBLEMS

PORT

output Input inpedance

printer

powered,

, 74LS05).

+/-

lsolate

PROBLE}IS

PSG,

Bad

,nodify

controller, 6850,

cable was

recycle

opto-isolator

68901 MFP,

12v

supply

bad line(s).

MFP

receiver,

is

chips.

of

pullup

resistors

MFP.

inserted

power.

white unÍt

chip, 6850, inverter

driver,

blown.

printer

on

is less

or

Use diagnostics

than

printer.

PSG

was

(74LS04

chips,

to

ohn

lK

Does

Does not

after cold

No

is inserted

Does

Mega

Service Manual

DMA PORT

not

function

REAL

TIME

not

function Bad

save tine Bad batteries,

boot

BLiTTER

vídeo

PROBLEMS

when Blit

not functÍon

PROBLEMS

Bad DMA Controller,

(loading

CLOCK PROBLEMS

RTC PAL

Junpers

nust

be cut before

Replace

problen.

the bus).

chip,

below

blitter

5.2

clock

power

a¡rd

blitter

chip

Menory

Controller,

chip, crystal.

off

sense circuit.

right

to

will work.

if

above step

Synptom Checklist

of blitter

doesn't fix

L772

chip

This

in

taken

The

context

problems

ôartridge

user

troubleshooting

necessary

flowchari,

where

result

troubleshooting

details

of

in which

for which

is covered

would

Atthough

in solving

reading

necessary,

in repair

DIAGNOSTIC

sectÍon

using

the the the

in the

all

run

guide,

thorough

a

sone

the

and swapping

the

of

SECTION

sumnarizes

the

SIX

FLOII¡CHARTS

using

Mega

cartridge

cartridge cartridge

would

troubleshooting

the tests,

the

take

and

understanding

problens, in

docunentatíon

out

Problem.

diagra.natic

in

the

not sho$m;

are

be

not be

look up

action

of

most cases

the

on

indicated

the

forn

diagnostic

this

used,

including

useful.

guÍde.

In

errors

reconnended.

syste¡n

the

following

diagnostic

conponents

steps

the

cartridge'

of

the

sone

the

shows

Usage

general, the

the

in

be

may

the

cartridge

will

(if

more than

kno*n whether

system

good

Extreme

circuit

easily

can plastic

where

part.

first

the

has been

Handting

care

chips.

be

carriers

Replacement

replacenent

indicated,

is

one

other

If part

is

rePaired.

of

should

They are

damaged

or

by

conductive

on

Procedures

indicated,

is

components

good

by

Integrated

taken

be

sensitive

very

careless

replace

later

are

replacing

Circuits

handling

when

to static

har¡dling.

when

foan

replace

at a

one

replaced,

in

the

Keep chips

in use.

not

conponent

the time)

systen

the

with

once

integrated

electricity

in their

a

verify

the

and

Mega

Service

Manual

6.t

Diagnostic

Flowcharts

START

CONT\ECT

TERM¡NAL

TO RSæ2

CYCN-E POWER

DISPLAY TEFINô.¡AL

DAGNOSTIC

FEPLACE

PER

DIAGNOSTIC

GUIDE

PORT

ON

?

PARTS

IS DISPI.AY

RE.ADABLE

REPLACE

PARTS

PER

DIAGNOSTIC

GI,JDE

CYCLE POWER

?

TESTS

ALL

RI.}.¡

ERROR?

Mega

Service Manual

MEGA/ST DIAGNOSTIIC

6.2

FLOtll

CHART

Diagnostic

OTHER?

Flowcharts

NO ERROR ON

DAGNOSTIC

RUN DISK

DAGNOSTIC

OR

REPLACE

DRIVE

PROBLEM

FOLAD

CON¡TACT

TECHNICAL

SUPPORT

?

ATARI

TRACE

FROÌ\, VDEO

APPROPRIATE

CONTINUOUSLY

SIGNAL

SHFTER

OTJÏPUT

RUN

TEST

TO

Mega

Service

MEGA/ST

DTAGNoSTTTC

6.3

FLoW CHART

Diagnostic

Flowcharts

NIO

ON OR

DISPLAY

ìvlOÀtTOR

TEruINAL

t€

FEPLACE

GLUE

Fts232

DISPLAY

\ t/t/

t€

TN

\'

1. CI€q<

2. REPLACE

OSCILLATOR

1. GLUE

2. ltlBMORY

SHIFTER

FIEPLACE:

CONTROL

3.

CPU

FEIVIOVE

NSPECT

TEST FOR

SI-{OFITED

SHIELD PCB

+

5

V

YES

FEPLACE

POWER

SUPPLY

l€

?

REPLACE

PCB

FEIVIOVE

RE€HECK

Sl-lORT,

1.

SEE

THEORY

OF OPERATIO¡¡

2 REPLACE

3.

COf..¡TACT

.IECHNICAL SUPPORT

Mega

Service

PCB

ATARI

Ma¡rual

DAC¡l'.lOSTlC

REPLACE

PER

DIAGNOSTIC

GUIDE

PARTS

6.4

Diagnostic

Flowcharts

NO

Ì\¡O

DISPI.AY, ERROR

¡úHZ

32

cLoo< ?

OTJTPUT

FROM

SI-IFTER

FìEPLACE

FAT-}G

OUTPUT

PART

TRACE

TO COI\¡€CTOR

REPLACE

XTAL

RESTART

REPLACE

SHFTER

RESTART

Mega Service

Manual

MEGA/ST

REPLACE tì/EMORY

CONTROLLER

DrAGNoSTrrc

6.5

FLow

CHART

Diagnostic

RESTART

Flowcharts

PARTS

SECTION

LISTS

AND

SEVEN

ASSEMBLY

DRAWINGS

Mega service

Manual

7.I

Parts

List

Drawings

&

MEGA PARTS

LIST

PART

NUMBER

cA200055-00 cA200093-001 cA200008-001 cA200018-001

cA200022-001

cA200025-00L cA200039-001 cAz00040-001 cA200041-00L cA200042-001 cA200043-001 cA200054-00L

c070350-003 c070352-003

clû3047-001

cAo70025

DESCRIPTION

1

PCBA

PcBA

MEGA

MEGA 2/

MEGA MEGA MEGA KEYBOARD MEGA

MEGA KEYBOARD MEGA KEYBOARD MEGA MEGA

FDD FDD uNrr FDD uNrr

STM1

cAP

CAP 39pF

cAP

CAP 150pF

cAP

(l¡le

(1Me

POWER SUPPLY

2 CASE 4 CASE

KEYBOARD CASE

KEYBoARD

KEYBOARD CABLE

uNrr

MOUSE

30pF 50v

100pF 50V 330pF 50v

1000pF

cAP 0.1pF

cAP

O.221tE

CAP 0.47¡:F

cAP

4.7pF 25V ELEC

cAP

10pF

cAP 47ytF

cAP

100pF 16V

cAP

1000pF

cAP

4700¡rF L6v

cAP

L00L¡rF

cAP

5-30pF TRIMMER

RES O OHM

RES

5.1

RES

27 OHM 33

RES

47 OHM

RES

75 OHM L/AW

RES

1OO OHM L/4W

RES

].50 OHM

RES 220

RES

470 OHM

RES

].K OHM T/AW

RES 1.2K

no¡¿)

MEGA

no¡¿) MEGA

CASE

4

(1v

(r¡4

(ru

BOTTOM TOP TOP

COMPLEÎE

CASE

CONNECTOR

(on¡r,y)

eyre) gyre)

ayrn)

ASSEMBLY

+5% cH.

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L/4W 5å CARBON

5% CARBON

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5% CARBON

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59" CARBON

AXIAL AXIAL

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SUBASSEMBLY SUBASSEMBLY SUBASSEMBLY

SUBASSEMBLY SUBASSEMBLY SUBASSEMBLY SUBASSEMBLY SUBASSEMBLY SUBASSEMBLY SUBASSEMBLY SUBASSEMBLY SUBASSEMBLY SUBASSEMBLY

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DESCRIPTION

LOCATION

c070567-004

c070 1 59

c070

448

c014384 c070205 c070471

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6

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c0?0790

c07024L-002

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c10028

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c025982

c025913 c025915

c0259L4

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c0259L2

c025986

c025981

c025983

c025984

c025985

cr0L7t2

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2.2R

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5.1K

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12K

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51.K

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GLOSSARY

SECTION NINE

OF PART

NAMES

AND TERMS

the

source

graphic

patterns

and destination

chip which is

block

and

BITBLiT--Atari

used to tra¡rsfer

with

between

transfer.

BUS

ERROR--GIue

there

to

memory

an illegal

causes

CPU--the

is

a device not responding

68000 microprocessor.

DMA--direct

from

external

but the Menory

exception

has

problem

a

access

¡nenory

asserted BERR

with

(attenpting

processing.

access. Process in

storage device to RAM,

storage. Transfer is the CPU,

place.

DMA

CONTROLLER--Atari

process.

EXCEFIION--a

so the CPU

Glue

arbitrates the

All

disk I/0

state

proprietary

in activity, saves what it will later in RAM, fetches executing at the address

processing doing

by intemupts, instructions,

Section Two,

is

done, the

before the exception

Systen

detail.

actually

memory

of

a combination

which

to

the

current cycle. This

(for

Controller fails

to write

very fast,

can be

processing

bus between the

chip which

goes

through

which the

a vector

processor

need

(address)

vector. When

processor

occurred.

or

Errors,

or a 68000 reference for nore

DMA

a

from

a source to destination

of any

was set up

inforn

exa.nple, CPU

the

device.

logical

prior

processor

could be due

tries

to assert DTACK),

ROM).

which

or

takes

to

data

from RAM

place

A bus

is

independent

while DMA

CPU ar¡d DMA.

controls

this device.

stops the

resune

to

from RAIft,

the

the exception

will

continue what

Exceptíons

emor conditions.

can be caused

It is

operations

to the

that

read

to

op

error

tra¡rsferred

to external

of

is

taking

DMA

the

curent

acbivity

and starts

it was

Atari Mega 2 User guide

Specifications and Main Features

Frequently Asked Questions

User Manual