Zenith Z-39 Technical Training Manual

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Technical

Z-39

VIDEO

TERMINAL

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Training

DISPLAY

Contents

Chapter

Introduction

THE

LIST

LIST
LIST
SPECIFICATIONS

1:

Description

Z-39

OF

TOO

OF

TEST

OF

SUPPLIES

SERVICE

DISPLAy

CURSOR

KEyBOARD
EDITING
TERMINAL
PRIliTER
ENYIRONMENT
POWER
DIMENSIONS

Installation

Voltale

leyboard

Video

Conneotions

Interfacing

DTE
SELF-CHECK TESTS
POWER-ON

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Keyboard
leyboard

Display

and

INDICATOB

and

Specifications

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MANUAL

LS

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AND

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COMMUNICATIONS

COMMUNICATIO.S

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Selection

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Indicators

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Un1t

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DCE

Devices

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FUNCTIONS

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Adjustment

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

. . . . . . . . . . .

1-10

1-10

1~11

1-14
1-14
1-15

1-15

1-1

1-1

1-2
1-2

1-3

1-3

1-4

1-4
1-4

1-5
1-5
1-5

1-6
1-6
1-6
1-6

1-7
1-7

1-9

1-7

Chapter

Theory

DETAILED

2:

General

of

Operation
Vertical
Video
Horizontal
Horizontal

I:EYBOARD

TERMINAL

VIDEO

POWER

Amplifier

CIRCUIT DESCRIPTION

Pover-Up
Serial
CPU

and

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CLOCK
CHARACTER

DEFLECTION/DRIYER CIRCUIT
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Horizontal
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Video

su~PLr

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Oscillator

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Scan

ASSEMBLY
LOGIC

and

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Control

Map

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CIRCUIT

GENERATION......................

Circuits

Clrcuits
Scan

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and

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BOARD

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2-2
2-2
2-2
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2-3
2-3
2-4
2-4

2-5
2-7

2-9

2-11

2-12

2-15

2-15
2-15

2-16

2-17

2-17

i

Cbapter

Introduction

KEyBOARD

ALPHABETIC
CONTROL

SPECIAL PURPOSE KEyS
lEY

Setup

Entering

Menu

3:

Operation

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Menu
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3-8

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3-9

3-1

3-12

3-13

3-1.11

3-16

3-16

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Cbapter

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Introduction

CABINET
CHASSIS
TERMINAL LOGIC
POWER
VIDEO CIRCUIT
CATHODE-RAY

Cbapter

SUPPLY

5:

Introduction

Satety

WARNINGS:

CAUTIONS:

Cleaning

AdJust.ents

YideQ
CRT

In~pection

Testing

Pover

Ter.inal

Terminal

Video

YideQ
Transistor
CRT

Keyboard

Detailed

Disas~e.bly

and

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TOP
BASE

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REMOYAL
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BOARD

TUBE

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Servicing

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Procedures

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1-2:

1-3:

1-4:
1-5:

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2-1:

2-2:

3-1:
3-2:
3-3:

3-4:

3-5:
3-6:

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4-2:
4-3:
4-4:
4-5:
4-6:

5-1:

5-2:

5-3:

5-4:

5-5:
5-6:
5-7:

5-8:

5-9:

5-10:
5-11:

5-12:

Video
USA

LED

Tilt
Voltage
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Overall

Z-39

Overall
Alpbabetic
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GERMAN
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UNITED
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THE

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terminal.
THEORY

theory
DETAILED

OF

OPERATION/CIRCUIT DESCRIPTION

of

operation

DISASSEMBLY

disassembly
SERVICE

INFORMATION
inspection,
level.

PARTS
component

APPENDIX
APPENDIX

LIST

views,
A
B

is

divided

--

Describes

and

testing,

--

Provides

Provides
Provides

into

Describes

interfacing,

the

with

--

reassembly

--

Provides

and

exploded

and

reference

foreign
escape

the

following

the

hardware

and

keys,

circuit

Provides

to

functions,

descriptions.

instructions

the

circuit

information

troubleshooting

views

designator

keyboard

sequence

and

power

--

to

with

information.

information.

parts.

provides

on.

and

modes

Describes

for

board

on

cleaning,

the

part

numbers,

index

hardware

level.

circuit

to

part

information

of

the

the

hardware

board

board

numbers.

SCHEMATICS

LIST
The

OF

TOOLS

following

terminal:

• Nut

•

•

•

•

• IC

•

•

driver,
Standard
Phillips
Small

diagonal

Long-nose

puller,
Desoldering
Soldering

Detailed

list

of

1/""
screwdriver,
screwdriver,

cutters

pliers

HE-490-111

bulb

station

circuit

tools

is

1/4"

'1

and

and

HE-490-189

blade

Weller/Heath

board

schematics.

recommended

12

point

GDP-110B

for

servicing

the

2

LIST
The

servicing:

OF

following

TEST

EQUIPMENT

list

of

test

equipment

is

recommended

for

NOTE:

•

•

•

•

•

•

•

LIST

The
servicing.

Equivalent

Oscilloscope

Logic

pulses,
impedance

Digital
zero

Variable

Oscilloscope

50

pF,

Video

monitor.

High

OF

following

probe

to

4

monitor

voltage

SUPPLIES

--

and

indicating

states.

voltmeter
one

megohm.

power

ns

rise

Zenith

list

items

--

DC

DC

supply

probe

--

Hodel

probe

of

of

test

to

100 HHz,

to

20 HHz,

logic

Heath

--

High

Heath

--

--

Low

time.

RGB

color

ZVH-135.
Zero

consumable

equipment

capable
one,

Hodel

Zero

IT-7410.

impedance
Hodel

to

capacitance,

and

to

40

supplies

may be

dual-trace,

of

logic

input,

SH-2215.

120

VAC,

adjustable

monochrome

KV.

Heath

is

substituted.

triggered-sweep.

detecting

zero,

recommended

and

zero

3

composite

Hodel

to

amperes.

10

ns

high

1000

from

wide

IH-5210.

for

single

volts,

15 pF

band

to

•

Heat

•

Cable

•

Solder,

•

Desoldering

•

Lint-free

sink

ties,

compound,

HE-354-59

60/40,

braid,

cloths

HE-205-0303

HE-331-13

HE-490-185

3

SPECIFICATIONS

DISPLAY
CRT

Display
Display
Character
Character

Character

Video

Attributes

Format

Size

Type
Size

Set

12"(30.5

video

25

6.0"

8 x 10

0.2"(5
wide

Normal:
upper­punctuation,
characters

Alternate:
superscript,
scientific
characters

Normal
underline
intensity
character

screen

rows

of

high

character
mm)

(approximate)

128

and

or

cm),

P31,

80

characters

x

8.5"

high

characters;

lowercase,

and

128

foreign
notation,
(VT-100)

reverse
character,
character,

green,

wide

cell

x

0.1"(2.5

numerics,

33

graphic

characters;

characters,

and

character,

normal
normal

nonglare

mm)

95

ASCII,

95

33

graphic

or
or

ASCII,

normal

half­blinking

or

Refresh

CURSOR
Type

Attributes
Controls

Addressing

Rate

60

Hz

Underline
block

On,

off,

Up,

down,
tab,
return

Direct

back

or

or

or

left,

tab,

(CR),

relative

reverse

blinking

right,

home,

and

line

(solid)

backspace,

carriage

feed

video

(LF)

4

KEYBOARD
Unit

Layout

Indicators

EDITING
Editing

Erasing

AND

ERASING

91-key,
key

keyboard

DIN

ergonomic

6-foot
Split:
style
and

14-key

Visual:
and

CAPS

Audible:

(programmable

1 kHz

FUNCTIONS

Insert
delete

Erase

of

line,

and

erase

detached,

(182

77-key

with

POWER

LOCK

Key

for

200

or

delete

line

page,

erase

to

conforming

standards

em)

coiled

standard
special
numeric

ON,

(LEDs).

click

on/off),

ms

character.

erase

to

beginning

low-profile,

to

with
cord
typewriter

function
keypad

KEYBRD

with

line,

beginning

LOCK,

each

beep

erase

of

page.

sculptured-

European

a

keys

OFF

key

entry

tone,

Insert

to

end

of

line,

LINE,

or

TERMINAL
Type
Baud

Hode
Code
Format
Word
Stop

Sync
Parity

Rates

Length
Bits

COMMUNICATIONS

75,

ASCII
Serial
7-data
2

all
Auto

EIA

2400,
Half-

at

Even,

RS-232C

110,

other

150,

4800,

or

asynchronous

bits,

75 and 110

XON

odd,

9600,

full-duplex

baud

and

mark,

300,

one

baud

rates

XOFF

600,

or

parity

or

space

1200,

19200

bit

rates,

baud

1

1800,

at

5

PRINTER

COMMUNICATIONS
Type
Baud

Rates

Mode

Code
Format

Word

Length

Sync

Parity

ENVIRONMENT

Operation

Storage

EIA

RS-232C

Rates

same
Half-duplex
ASCII
Serial
7-data
Hardware
Parity

asynchronous
bits,

handshaking

same

Temperature:

(O-~O

degrees
Humidity:

Temperature:
or

-~O

to

Humidity:

as

main

one

as

32

Celsius)

10-90S

-~O

66

degrees

0-95S

port

parity

main

to

port

105

(relative)

to

150

(relative)

setting

bit

only

setting

degrees

degrees

Celsius

Fahrenheit

non-condensing

Fahrenheit

non-condensing

POWER

Voltage

Range
Frequency
Consumption

DIMENSIONS
Video

Unit

Keyboard

Weight

90-132
60

~5

13.6"
(34.5

1.35"

(3.3
Video

Hz
watts

high
x

high

x

unit:

volts

~6.3

Keyboard:

33.0

3.8

x

12.9"
x

x

18.25"

x

18.9

wide x

28.0

20.5

cm)

pounds

pounds

cm)
wide

(1.73

11.0"

x 8"

(8.50

kg)

deep

deep

kg)

6

Installation

This
connectors
start-up.

Voltage
The Z-39

while

either

into
voltage
instructions

WARNING:
cord

1.

2.

3.

4.

section

the

a

must

Place
that

Remove
then

Remove

shield

Set

the
two
heat

terminal
power

4-32

describes

on

the

Selection

is

configured

Z-39E

source.

other

The

the

the

remove

sink

and
power

be

unplugged
terminal

base

the

the
from

base

x

bracket.

than

four

6-32

1/2"

video

is
has

the

Figures

supply

chassis

6-32

the

base
x

the

underside

chassis

screws

the

display

during

configured

not

been

To

change

configured

1.1
develops

before

on

its
screws

x

5/8"

chassis.

5/8"

screw

down on

securing

location

and

manufacture

for

reconfigured

the

and

4.2.

proceeding.

side

are

screws

securing

of

the

the

of

controls,

keyboard

220

volt

terminal

one,

on

refer

lethal

the

accessible.

at

base
work

the

shield

necessary

for

operation.

before

to

to

DC

voltages.

work

points

the

chassis.
surface;

surface

power

to

indicators,

120

volt

it

operate

the

A,

then

the

for

operation

Verify

is

plugged
on a

following

The

so

a, C, and

supply

power

protectivE

remove

and

basic

that

power

D;

the

supply

5.

Carefully
power

6.

Select
operation.
to

marked

7.

Replace

screws

8.

Carefully
screws

9.

Place

the

lift

supply

the
pin

on

the

the

that

replace

that

the

terminal

the

power

circuit

jumper
Pull

corresponding

the

circuit

power

were

were

board.

for

white

supply

removed

the

removed

upright

supply

either

to

board.

shield
in

base

in

120

jumper

the

step

chassis

step

on

its

7

shield

or

240

straight

desired

and

the

4.
and

2.

mounting

until

volt

up and

operating

two

4-32

the

four

base.

it

clears

terminal

reconnect

voltage

x

6-32

1/2"

x

the

it

as

5/8"

Keyboard
The

following

1.2.

Voltage

1s a description

Figure

of

1.1

Selection

the

keyboard.

Refer

to

Figure

Keyboard
Keyboard

indicators,
Refer

to

information.

Cable

-~

The

and

Appendix

Connects

keyboard

is

available

A,

Figures

the

consists

in

1

Figure

USA

keyboard

of

several

through

1.2

Keyboard

td

91

keys,

different

6

. . . .

-=-

"::"!" ~ -::

t~e

for

video

four

foreign

display.

visual

languages.

keyboard

8

Keyboard

Indicators
Refer
POWER

to
ON

properly
KEYBRD

host

OFF

computer

LINE

computer.

CAPS

NOTE:

POWER

LOCK

All

ON

Figure

--

Lights

connected.

LOCK

--

--

Lights

--

LED

(green).

1.3.

Lights

control.

Lights

indicators

when

when

when

power

when

The

the

the

illuminate

.....

is

the

keyboard

keyboard

terminal

CAPS

o

•

.'9"

011

"OC.

ON

and

must

LOCK

red,

•

•

•• C ....

"'IIC

LOCK

the

unit

is

off-line

function

keyboard

is

be

enabled

except

locked

to

from

is

on.

for

is

or
operate.

the

under

host

Keyboard

Refer

The

to

tilt

located

Tilt

Figure

of

at

Adjustment

the

the

rear

1.~.

keyboard

of

LED

can

unit.

Figure

Indicators

be

1.3

adjusted

9

by

pressing

the

two

tabs

Figure

Til

t Adj

1.4

ustment

Video
The

video

Refer
Power
Contrast

Rotate

screen

1.

Grasp

the
in

2.

Grasp
or
22

Display

display

to

figure

ONIOFF

Control

the

video

to

the

both

desired

either

both

down

to

degrees

Unit

unit

1.4

Switch

display

desired

sides

position.

direction.

the

top

the

desired

of

overall

is a monitor

for

the

--

Turns

Adjusts

on

viewing

of

the

This

and

tilt.

location

the

the

contrast

the

cha!sis

angle

CRT

and

movement

the

bottom

position.

mounted

of

terminal

as

swivel

of

This

on a swivel

the

following

on

of

the

base

follows:

it

is

restricted

the

CRT

movement

or

and

right

off.

video

tilt

or

and

is

base.

controls.

display.
the

left

to

45

tilt

it

restricted

CRT

to
degrees

up

to

Video

Figure

Display

10

1.5
Unit

Connections
Place

the
in

Keyboard

the

rear

figure

ClUTION:

telephone
computer

Locate
keyboard

DTE
signals

DCE

RS-232

NOTE:

securely
When

RS-232

computer's

for

the

Connector

Connector

signals

Verify

connecting

cable

the

video

is

facing

1.6.

Connector

The

coiled

cord.

to

the

coiled

connector

to

a modem

that

or

improper

into

DCE

proper

display

you.

cable

Do

not

telephone

keyboard

on

(Main)

(Auxiliary)

to

the

connector
connector).

--

and/or

data

the

operation

terminal

the

on a

The

Provides

assembly

attempt

system

the

rear

Provides

computer.

--

terminal

DTE

and

DTE

connector

(refer

solid
terminal

cable.

Provides

DCE

directly

the

to

connect

or

Connect

of

the

the

devices

cable

of

the

to

work

resembles

the

surface

connections

necessary

damage

video

necessary

the

or
connections

terminal
to

a

and

the

computer

and

signals

a

conventional

the

keyboard

could

the

cable

display.

ElA-standard

necessary

a

printer.

may

computer,

other

hardware

turn

are

illustrated

for

or

result.

to

the

EIA-standard

are

result.

plug

end

into

it

until

the

RS-232

tightened

the

the

manual

keyboa

When

into
connector
connector).

When

(HE-134-1454)
manual

auxiliary
both

primary

POWER

to

After

cable

terminal's

Turn

Plu~

lAC

connecting
the

DTE

connecting

for

(DCE)

ports,

(DTE)

LINE

the

terminal.

verifying
into

the

video

the

power

receptacle);

(refer

the

connector

to

the

may

the

proper

connector.

the

printer

port

Connector

that

the

power

base

unit.

display

cable

then

terminal

the

terminal

have

for

--

the

connector

into

to

and

the

modem

to

connection).

must

the

Connects

power

until

press

hardware

to

be

used

Since

operate

host

the

an

appropriate

the

a modem,

other

a

printer,

(refer

Plug

the

baud

computer.

1'5V

switch
located

front

power

end

manual

the

at

the

power

is

on

is

switch

plug
into

a

to

the

rate

off,

the

facing

power

the
the
for

null

printer

printer

setting

same

source

plug
rear

source

to

ON.

RS-232
modem's
the

modem

cable

baud

via

the
of

you.

cable

(DCE)

proper

cable

hardware

into

applies

rate

power

power

the

as

the
to

the

cord

"

POWER-ON

INDICATOR

When

the

keyboard
either
or

the

After
corner

0:00:00

or

INSERT

you

turn

the

terminal

10

to

of

and/or

on

should

keyboard

30

seconds,

the

screen.

one

MODE.

the

terminal,
light.
is

is

not

The

or

more

~

fp:O~D

..

Terminal

If

not

connected

connected

a

cursor

25th

messages

•• n •••

Figure

the

the

to
should

line

~

CABLE

Connections

POWER-ON

POWER-ON

to

the

an

acceptable

appear

may

also

such

1.6

as

CABLE

indicator

indicator

terminal

in

display:

CAPS

LOCK,

on
is
correctly

power
the

upper-left
time

not
source.

OFF

lit,

LINE,

Interfacing
The

terminal

a

computer

through

following

interface
CAUTION:

to

a

radiation.

DTE
On

the
connectors,
connector
connector

Table

provides

~~7~:

RS-232C

telephone

computer

and

DCE

rear

1.1

The

standards

is

designed

system.

discussion
with

FCC

connects

to

provides

information

computer

a

regulations

with

Devices

panel

marked

the

printer

It

may

lines

computer.

a

of

DCE

to

information

or

or

(via

covers

shielded

the

terminal,

(auxiliary)

the

on

the

modem

improper

to

be

be

directly

a modem)

the

require

host

or

other

DCE

used

used

cable

computer

on

operation

as

necessary

that

to

there

and

peripheral.

the

connector.

with

an

input/output

connected

to

any

information

the

terminal

minimize

are

two

DTE

(main).

or

modem and

DTE

connector

the

terminal

may

result.

or

connected

computer.

be

spurious

standard

The

must

device

The

for

proper

connected

RF

DTE

the

DCE

and

Table

meet

for

1.2

12

Primary

-------------------------------------------

PIN

#

-------------------------------------------

,

2

3

4

5
7

20

Serial

SIGNAL

NAME

GND

XMT
REC

RTS
CTS
GND

DTR

Connector

Inputl
Output

o

I

o

I

o

(DTE)

SIGNAL

FUNCTION
Protective

Transmitted

Rec

e i

ved

Request
Clear
Signal

Data

to

to

Ground

Terminal

Ground

Data

Data

Send

Send

Ready

Auxiliary
PIN

,

--------------------------------------------

1

2

3

4

5

6

7

8

20

HOTE:

SELF-CHECK
As

check
is
video
sound.
error
further

SIGNAL
NAME

GND

REC
XMT
RTS
CTS
DSR

GND

CD
DTR

soon

detected,

Serial

Input/
Output

*

indicates

TESTS

as

you

tests

screen.If

Table

messages.

are

an

1.3

infor~ation

Connector

I

o

I

I

•

o
o

*

o

pins

turn

on

performed

appropriate

no

faults

lists

Refer

to

and

(DCE)

SIGNAL
FUNCTION

Protective

Received
Transmitted

R e

que

s t t 0

Clear

• 0 a t a Se t
Signal
Carrier
Data

tied

the

are

the

Chapter

instructions.

to

Terminal

to

terminal,

to

verify

error

found,

tests

Ground

Data

Data

Se

Send
Rea

d y

Ground

Detect

line

20

message

performed

5,

"Service

n d

Ready

a

series

proper

a

short

will

of

internal

operation.

be

beep

and

the

Instructions"

self-

If

a

displayed

tone

corresponding

will

for

fault

on

the

Self-Check

TEST

ROM
RAM
CRT

Controller
Keyboard
.,_

...

.;,latlle

Tests

RAM

ERROR
ROM

RAM

CRTC

Keyboard
NVRAM

MESSAGE

Checksum
Fault

Error

Checksum

13

/

Chapter

2:

General

Information

Theory
The

following

the

terminal's

Refer

US[~

......

~ILI.EL£

~":'.£ L I'.r--~

of

to

Operation

paragraphs

major

Figure

!xPAIo;S

D

2.1,

IO~.

soon

OR

u

~

OC

P.

H'

OR

',\0:;'('.,

~OCK[l

provide

assemblies.
the

overall

a

block

block

diagram

diagram.

Ii

CO,:lROtL[P

description

I

D!O

of

CDI.'

(K

P~OC'~·.~

RO~1

115

BYT[S

UA1

C[UCH£D

K!YBOU:

\~

IT

!~cor·I·.c.

M

IOCIC

Figure

Overall

Block

2-1

Diagram

UlRl&UT[S

co,.

TAOLLE~

1

Vertical
The

transistor-transistor
terminal
to

synchronize

pulse.

Oscillator

logic

The

oscillator
amplifier.
complementary
sweep
retrace
period
provide
are

current

stage

of

normal

located

the

This

output

to
generates
sweep

on

board

the

vertical

in

turn,

drive

display

the

video

(TLB)

output

feeds

amplifiers

the

a

output.

height

deflection

logic

is

coupled

frequency

is

the

vertical

fast

vertical

The

on

(TTL)

applied

vertical

I

and

deflection

VERT

the

board.

input
to

with

to

II.

retrace

SIZE

CRT.

signal

the

the

a

driver,

This

control
The

from

vertical

incoming

differential

which

stage

yoke.

for

the

is

vertical

the

oscillator

sync

drives
develops
The

vertical

retrace

adjusted

circuits

the

to

Video
The

Amplifier

positive
amplifier
cascade.
drive
located

the

on

Horizontal
The

positive
horizontal
the

incoming
information
inverter
inverted
gain
driver
output
develop
the
the
the

via

is

circuit

CRT.

CRT

video

the

raster.

video

stage

This

stage

cathode

the

Oscillator

horizontal

oscillator

pulse.

on
stage,
signal
the

coupling

applied

ramp·

The

WIDTH

deflection

which

of

video

the

which

is

to

uses

voltage

The

signal

consist

amplifies

the

driver

which

The

PHASE

CRT

screen.

amplifies

applied

transformer.

the

a

winding

coil

is

horizontal

board.

from

of
the

CRT.

The

board.

sync

pulse

syncs

control

The

to

a

horizontal

on

for

the

adjusted

oscillator

the

TLB

two

Signal

video

from

the

oscillator

the

signal.

driver

The

output
the
horizontal

to

is

applied

transistors

to

a

amplifier

the

horizontal

is

used

The

stage

output

stage.

flyback

deflection

provide

circuit

to

connected

level

circuit

TLB

is

coupled

frequency

to

center

signal

amplified

to

provide

signal

The

transformer

normal

is

the

video

necessary

is

the

is

fed

and

current

from

the

horizontal

to

yoke

width

located

in

to

with

video
to

of

for

on

to

the

an

Horizontal
The

horizontal

Scan

conjunction
the

retrace
flyback
focus
using

transformer

and

acceleration

rectifier
transformer.
reference

voltage

potentiometers.

~uooly

circuitry

output
with
pulse

The

and

Power

the

develops

also

diodes

voltage

for

The

horizontal

is

stage

flyback

grids

at

from

the

located

Supplies

functions

transformer,

12

kV

provides

of

low

voltage

the

FOCUS

on

for

the

and

scan

the

2

as

the

various

CRT.

windings

diode

rectifiers

BRIGHTNESS

and

rectifier

video

an

electronic

the

high

anode

of

supply

This

is

on

control

deflection

switch.

amplitude

the

CRT.

voltages

for

accomplished

the

1s

the

diode

power

board.

In

of

The

the

DETAILED

CIRCUIT DESCRIPTION

This

section
keyboard
the

power
KEYBOARD
Refer

to

following
NOTE:

The
represent
device's

The

keyboard
single-chip
and

a

timer

the

status
provides
matrix
under

for

All

keys

control

more

the
comprise
eleven
diode

scan

are
generation
The

port
lines
the
line,

of

selected

the
keyboard.
the

eight

port

0

bits

provides

assembly,

supply.

ASSEMBLY

the

keyboard

paragraphs.

symbols

the

logic

design.

assembly

microcomputer

US.

U1

indicator

serial

communication

are

of

information).

keys

a

matrix

except

lines

placed

of

phantom

2

bits

the

1

of

scan

sense

lines
Resistors
sense

AO

through

terminal

on

flow

performs

LED(s),

scanned

U1

(refer

RESET

keyboard

or

an 8 x

at

each

CO

(LSB)

16

decoder

line

R11

lines.

a

detailed

assembly

the

schematics

of

contains

U1, a 1

utilizing

to

BREAK,

consisting

crossover

key

signals

through

being

are

checked

through

The

active-low

A7.

circuit

logic

board,

schematic

the

circuit

an

8 x

to

keyboard

enables

with

a

data

sheets

CTRL,

l'

configuration.

point.

due

C3

U2.

The

driven

for

R18

in

11

16

matrix

the

the

strobe

of

to

(MSB)

port

low.

a

serve

sense

description
video

as

this
rather

matrix

circuit

you

read

service

than

keyboard,

decoder/multiplexer

scanning,

timer

terminal

for

logic

beeper

scanning

on

the

8021

and

the

two

SHIFT

eight

The

multiple

of

2

After

key

as

sense

A

keyswitch

diodes

U1

control

bits

selecting

closure

pullup

lines

key

drive

on
resistors

are

of

the

board,

the

manual

any

specific

a

U2,

controls

T1,

board.

The

technique

microcomputer

keys

lines

and

and

prevent

the

closures.

the

scan

U2

with

a

scan

the

matrix

read

by

and

and

for

RESET

The
active-low
These
keys
and

The

NORed
input
R19

keys

to

input

output

together

of

and

resetting

hardware

inputted
of U 1.

The

chip

sen~

the

to

line

BREAK,

keys

all

send

to

unique

port

of

U1

via

capacitor

U1.

reset

directly

U4D

buffers

the

keyboard)

pullup

CTRL,

utilizing

have

the

by

the

The

of

resistor.

special
keycodes.

1

(Bn

SHIFT

U3A.

RC

C8

provide

output

the
to

port

the

to

and

the

pullup

functions

of

keyes)

The

output

network

of

U3A

terminal.

1 (B2) and

data

input

Port

two

resistors

The SHIFT

U1.

and

of

composed

a

minimum

is

The

stream

T1

of

1 (B3)

3

SHIFT

and may

RESET

U3A

reset

also

RESET

the

(RCV)

U1.

outputs

keys

are

R8, R9, R10,

be

keys

of

are

BREAK

is

applied

R19

key

and C8.

pulse

buffered

BREAK

CTRL

key

Signal

Resistor

the

direct-drive,

used

ORed

with
together

are

to

width

by

U4E

key

also

to

port

(serial

R22

serves

serial

and

R21.

other

logically

the

RESET

Resistor

for

for

is

1

(80)

data

data

as

generated
logic

A

for

board.

3.579
the

drives

Resistors

timer

OFF
U4B,
LEOs

interval.

LINE,

and

02, 03,
(POWER
and

D4
terminal
of

power

by

MHz

internal

timer

R1
and

U4C.

ON)

are

logic
to

the
Resistor

crystal

circuit

and

KEYBRD
Resistors

and

fed

turned

the

keyboard

is

control
R2

and

Port

04.

directly

on

board.

keyboard

R23

connected

and

US

for

capacitor

1

bits

LOCK

R4, R5,

Resistor

from

by

U1

The

assembly.

(XMT)

serves

via

as

between

timing

the

piezoelectric

B4, B5, and

LED

indicators

and

R7

is

the

+5

in

response

LED

01

is

buffer

the

references.

cg

are

R6

are

the

volt

to

turned

U4-F

line

pullup

XTAL 1 and

beeper

selected

B6

drive

via

the

bias

bias

line.

resistor

The

commands

on

by

to

the

resistor.

XTAL 2 of

The

port

to

set

the

CAPS

buffers

resistors

LEDs

from

the

application

terminal

1

T1.

the

U4A,

for

D2,

the

bit

LOCK,

for
LED

03,

U1

B7

01

Approximately
through
+5

volts

pin

DC
Capacitors
volt
connector

TERMINAL

Refer
following
Power-Up

To
being
reset

pressing

The
0401,
circuit

C416

of

pulls

(Vcc)

to

set

the
changed
can

power-up

resistors

U406C. When

is

in

NAND

gate

this

ground

LOGIC
the

paragraphs.

and

be

the

microcomputer
C416
inputs

output

charg~&"th~ough

for

allows

+9.4

8

to

with

C3

through

to

the

BOARD

terminal

Reset

terminal

by

initiated

SHIFT

reset

R408

a

discharged

U406C

output

U433

U406C

U433

volts

voltage

C1

and

C7

keyboard's

pins

are

logic

Circuit

back

software

either

and

RESET

circuit

and

the

low

voltage

resets.

resistor

to

become

to

exit

DC

is

regulator

C2

used

and

C10

integrated

1

and

board

to

its

escape

keys

for

R423,

terminal

condition.

and

the

to

a

After
high;

the

applied

as

provide

U5.

line

to

US

filter

decoupling

circuits.

3.

schematic

original

operating

sequences,

by a power-up

on

the

the

terminal

capacitor

is

This

output

level

this

R408.

thus

reset

first

This

C416,

holds

(pin

that

initial

action

the

condition.

the

keyboard

regulates

capacitors.

as

you

U433
or

by

keyboard.

consists

and

turned

one

8)

high.

insures

reset,

causes

resulting

assembly

the

output

for

the

The

keyboard

read

mode

must

be

the

after

reset.

simultaneously

of

diode

integrated

on,

capacitor

input

(pin

Resistor

that

capacitor

both

low

at

to

+5

A

10)

R423

its

Simultaneously
also
terminal,

power

resets

up,

the

capacitor
immediately
the

same

input

to

function

U406C.

sufficient

operate

properly.

preSSing

U433.

probability

begins

to

override

Since

C435

to

charge

as

the

Capacitor

When

the

two

of

is

capacitor

C435

the

reset

the

SHIFT

SHIFT

keys

have

accidental

in

a

discharged

through

finally

condition

and

4

and

and

RESET

to

be

reset

resistor

resistor
charges

RESET

keys

actuated

is

condition,

R425.

on

to

and

allows

keys

are

on

the

to

minimal.

but

This

the

other

a

level

U433

keyboard
reset

the

At

performs

that

to

is

simultaneously

pin

2)

causes
discharges
the

terminal.

protected

accidentally

The

low

that
also
(U427).
inverted

reset

Resistors
pulses
composed

less

keys

down

applied

Since

by

input

R425

that

of

than

the

together.

to

initiate

capacitor

to

a
Because

from

unplugged
is

as

the

U~25D

is

could

R401,

time

pressed,

TTL

low,

a

false

sent

the

clear

enable

before

pulled

and

R401

otherwise

R425,

it

This

reduces

the

the

reset

from

to

low,

takes

reset.

a

logic

C435

the

reset

the

input
input
it

and

and

low

to

discharge.

output

lines

1n

the

the

video

reset

to

to

is

applied

the

screen

capacitor

reset

C435

to

actually

the

time

from
of
event

circuit

the

U~27

the

forms

the

U406C

float

that

display

from

video

is

to

is

blanked
C435
terminal.

a

time

press

the

two

keyboard

Once

goes

high,

the

unit.

the

suppression

pulled

the

data

integrate

constant

the

keys

this

high

the

keyboard

keyboard

high

input)

during

The

SHIFT

must

(plug

capacitor

and

terminal

circuit

(and

reset.

any

noise

network

that

and

be

P~03

resets

is

is

and

is

RESET

held

is

the

After
begin
display

Serial

The

asDTE

DCE
connect
can

a

reset

the

RAM

Ports

terminal

(Data

(Data

the

be

connected

initialization

Computing

Microcomputer
This

terminal

for

for

IC

contains

to

an

asynchronous

linking

protocols.

U433

reading
serial

responds

or

IIO

-pa<t.

writing

communications
terminals,

port
overrun,

receiver's

Since
double

contains

which

U433

buffer,

interrupt

can

is

complete,

and

initializes

has

two

Terminal

terminal

to

U433

controls

a

built-in

communicate
peripheral

to

a

serial

to

provides

with

printers,

two

buffers

could
usually

only

firmware

routine.

the

RS-232

compatible

Equipment),

Equipment).

to

a

computer

a

printer.

the

serial

with

other

communications

devices

port

the

serial

using

interrupt

asynchronous

standard

or

computers.

occur

before

to

eliminate

if

the

UART

the

maintain

one

buffer

is

causes

This

two

CRT

and

the

The

DTE

or

modem

operation

port

peripherals,

element.

standard,

port's

modes

devices,

The

CPU

fails

beginning

the

transmit

used

U433

clears

controllers.

ports,

other

port

is

while

of

which

This

request

buffer.

to

such
receiver
the

possibility

to

of

the
link

at

the

to

the

scratch

one

is

configured

is

configured

normally

the

the

serial

enables

without

port

asynchronous

by

either

This

full-duplex

facilitate

as

other

input

respond

next

without

transmitter

used

DCE

ports.

the

the

is

useful

to

this

of

to

frame.

pad

and

as
to

port

need

the
a

output.

In

the

on

the

samples

asynchronous
received

taken

frames.

near

modes,

the

false

For

center

noise

of

start

rejection,

each

5

bit

rejection

received

a

majority

bit

is

must

provided

of

three

agree.

The

1/0

operation

port

modes

may

be

programmed

as

follows:

to

function

in

any

of

the

four

Mode

o

1

2

3

Proper

transmission
of
upon
uses

U433's
divided

in

TH1
software).
transmission
are
7200,

The

U433, a

line

timing

transmission

the

transmission

clock

by

if

75.

110. 150,

9600,

hardware

2-line

driver

Synchronous
CMOS
UART
variable
UART
variable
UART
variable

for

rate

operating

frequency.

12

(or

counter

This

rate.

and

required

to

(U442),

shift
interface

transmission

interface

~ransmission

interface

transmission

the

serial

generator

rate

generation

mode

mode

the

T1

1

is

configured

frequency

The

300.600,

19200

baud.
to

1-line

and a

Operation

1/0

expanslon

registers.

with
with
with

inside

of

the

1,

the

In

this

input

is

then

baud

rates

1200.

complete
output

quadruple

10-bit

rate.

l1-bit

rate.

ll-bit

rate.

1/0

data

U433.

are

possible

serial

transmission

mode,

is

in

the

divided

the

divided

that

1800.2000.2400,3600.4800,

the

multiplexer

ltne

using

frame
frame
frame

is

provided

Three

port.

Since

rate
oscillator
by

auto-reload

by

this

terminal

serial

receiver

TTL

or
and
and
and

different

and

are

is

256.
32

to

link

(U431),

by

a
dependent

this

terminal

generated

frequency

minus

mode

provide

will

consists

a

quadruple

(U429).

methods

the

value

by

the

support

of

from

is

Pin 4 of

U433.
the
this

When

auxiliary

line

computer
The

transmit

on U433

these
the
high

OR

port

regardless

Therefore.
transmits.

OR

gate

to

be

transmitted

select

The

clear
Signals
to

the
terminal
Signal

multiplexer

this

is

a

port

line
through
gates

s~le-ct·

when

When

U4430

bit

on

line

is

to

send

the

drivers.

.is

ready

detect

line

port

logic

to

the

drivers

an

is

from

bit

of
the
the

high

because

low,

OTE

OTR.

(RLSO)

U431
is

to

0,

the

is

logic

receive

U431

receive

are

OR

gate

the

is

high,

the

logic
port
port

select

~elect

regardless

of

the

OTE

(CTS) and

port

On

data

are

the

set

signals

connected

1,

sends

pin

tied

(U443C

port

select

the

level

bit
bit

inverter

port

transmits.

data

taken

auxiliary

ready

are

6

U431

pin

sends

of

data

of

U433's

directly

or

U4430).

output

of

the
is
is

of

the

terminal

directly

port,

(DSR),

all

tied

to a latched

data

U433's

received

serial

to

The

bit

(UQq8,

of

the

data

a

logic

a

logic

logic

UqqqC.

level

Thus

ready

from

the

and

the

together.

received

serial

from

port.

the

transmit

second

pin

OR

gate

to

be

1,

the

0,

the

when

(OTR)

U433

CTS,

received

1/0

pin

from

port.

the

input

7).

When

UQ43

transmitted.

OCE

port

output

of

the

data

the

control

and

passed

data

on

When

pin

to

is

of

port

line

Another
P r i n t "
DTE

mod

port
printer.
U432,
be

pin

enabled.

applied

7.

CPU

and

The

main
U433
U433
access
five-source
chip
serial
the

logic

and

contains

memory

oscillator/clock

channel.

total

board

feature

e • T

his

to

be

Integrated

1. The
At

from

U432,

Control

timing

its

two-priority

terminal

for

of

the

a

11

0 w s d a t a a r r i v

immediately

circuit

logic

this

time,

pin

Circuitry

and

control

associated

a

4K

x 8

(RAM), 32

circuit,

The

internal

firmware.

installation

serial

channeled

U448,

0

will

handshaking

11

directly

for

circuitry

read-only

I/O

lines,

level

ROM

ports

in g tot

pin

allow

to

the

(ROM,

memory

two

nested

and a high

holds

A

socket

of

additional

is

a

pass

h e

out

the

12

sets

the

pass

from

the

U433,

terminal

RAM,

(ROM), a 128

16-bit

interrupt

performance

approximately

is

included

firmware.

through

't

e r

min

a 1

DCE

port

a

logic

through

DCE

port

pin

is

established

and

control

timer/counters,

structure,

on

or

"Blind

fro m the

to

a

1

or 0 to

operation

will

logic).

x 8

random

full-duplex

one-half

the

terminal

by

an

to

be

a
on-

of

The 32

I/O

open-drain

bidirectional
separately.

Port

order

this

0

--

address

terminal

circuitry

respective
100

nanoseconds

goes

applied
the

Port

1)

riSing

is

low.

1

--

used

to

keyboard.
line
are

RFI

Bit

0,

allows
by
This
logical
the

15
setup.
all

from

buffered

suppresst'on.

2 (U433

this

bit

the

U433,

feature

rows

screen

minutes

This

RAM,

lines
bidirectional

I/O

Port

0
lines.
do

must

demultiplex

buses.

The

low

address

edge

Port

as

Bit

the

1

the

1 (U433
keyboard

by

pin

inverted

video

this

bit

is

of
saver
of

inactivity

bit

including

are

divided

ports.

functions

Since

not

have

The

address

later,

at

the

this

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of

the

is

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general

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pin

to

U425B

3)

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and

used

by U425D,

to

be

displayed.

causes

particularly

video

in

operation,

blanks

the

video

port,

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as

the

on-chip

the
address

pin

U441,

signal

2)
the

U425F,

as

the
SO

if

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RAM

into

of

the

memory

exits

is

(ALE).

purpose

line

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terminal

the

video

useful

Hz

where

this

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four

while

the

ports

ports

multiplexed

address

address

at

latch

inverted

where

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between

used

as

respectively,

video

is

connected

When

information

in

operation.

the

feature

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will

and

peripheral

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port

0

enable

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address

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the

terminal

the

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logic

enable

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blanking

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screen

is
a

manual

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enabled

initialized.

ports.

be

data

lines

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(U433,

U444B

is

Bit

board.

and

bit.

U427

to
to

the
also
turned

Port
3

are

0

is

described

bus

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low

devices

U433

onto

their

approximately

pin

30)

before

latched

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and

it

on

pin

the

communications

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filtered

When

pin

logic

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used

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reset,

lines

for

at

logic

13

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1

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unused

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off

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in

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7

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volts,
the

logic

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Bit

t

his

bit

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1

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4 (U433

handshaking

connector

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5 (U433
handshaking

connector

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Pr

int"

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the

For

bits,

refer
logic

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video

further

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to
board

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pulled

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5)

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through

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7)

pin

8)

circuit

information

video

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bit s the

up

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computer

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computer

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bit,

descriptions.

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as

OTE

line

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as

OTE

driver

as

as

a

pin

1).

regarding

and

paragraphs

output.

TU

P mod

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the

the

port

the

port

the

initial

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the

eke

recognized

keyboard

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signal

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CTS

signal

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RTS

input

synchronization

keyboard

RS-232

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y v i a

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to
firmware.
as

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the

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+5

at

SET

signal

bits,

terminal

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key

to

Port

order

2

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address

combination

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and
serial

3

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port
asynchronous
asynchronous

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character
indicates
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5
transfer

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at

character

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as

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instruction
video

memory

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byte

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pins
circuitry.

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CRT

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pin

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10

12)

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1

level

at

gate

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13)

last

14)
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become

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pins

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0

and

used
and

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data

as

11,

0

input,

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buffer

buffer

U401F.

CRTCs.

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21

to

28)

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2

form

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general

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respectively)

functions

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output.

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the

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logic

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ready

ready

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the

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signal

last

value

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external

total

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the

bit

1

0

level

the

0

level

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the

to

quickly

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memory.

16-bit

IIO

part
serial

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0

input

loading

(BRDY)

initiates

1

input

character

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of

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address

port.

of

at

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circuitry.

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The

Bits

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character

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higher

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bit

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DMA

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row

bus.

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bit

pin

of

8

Bit

5
request
the

PRT

(U433

to

CTRL

pin

send

signal.

15)
(RTS)

is

used

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as

from

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input

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to

the

selected

serial

port,

port

as

depending

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on

Bits
for

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U433

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6

and

transferring

PSEN

(pin

normal

internal
U433

receives

information

computer.
converts
attribute

provided).

attribute

U446

with
directly
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attribute

to

the

four

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writes

(U436).

placing

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The
enables
(U428)
are

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associated
location

7 (U433

signal

29).
fetch

program

character

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to

data

U433

display

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connecting

data

possible

the

character

20K

the

memory

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attribute

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pins

data

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the

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enables

operations

memory.

either

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key

character

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address

the

is

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address

chip

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secondary

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microcomputer

to

16

bytes

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data

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is

pressed,

data

with

sends

the

Signal

attribute

a

four-bit

attributes.

data

out

signal

select

data

a

in

video

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17)

between

store

external

versus

and

keyboard

and

the

attribute

(U~37

data

to

and

and

data

display

screen

are

port

enable

attribute

interface

the

keyboard's

sends

character

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U438)

and

the

bus

wide

1n

the

the

character

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the

bus

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places

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the

WR

0

and

output

program

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to

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data

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primary

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display

write

Signal

bidirectional

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the

character

chips

position.

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RD

signals

the

data

control

memory

to

microcomputers

or

the

host

microcomputer

the

terminal

already

to

the

enabling

Signal

(WR),

data

memory,

display

memory

from

bus

primary

data

and

in

an

used

bus.

from

the

bus

(the

bus

buffer

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bus.

applicable

U433

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U433
driver

bus

address

(U1)

After
appropriate
character
their
This
is

Memory
Figure

through
well

U433

corresponding

operation

described

Map

2.2
A12

as

other

has

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in

depicts

are

circuits.

placed

occurs

selector/demultiplexer

map.

the

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CRT

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data
and

the

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way

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display

terminal's

to

the

Chip

and

U423

selects

must

attribute

direct

9

data

be

transferred

(U418

circuit

memory

memory

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a

4K

increments

in

the

display

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memory

description.

map.

select

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from

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access

Address

circuit

to

8-output

of

the

memory

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respectively).

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lines

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data

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A15

as

ADCRES~

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m

m

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character
buffer

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m

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di

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access

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(U431

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bus

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signal

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follows:

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attribute

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hex

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in

from

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U438),
display
are

CRTC

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from

flip-flop

the

memory

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signal

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for a CPU

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accessed

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selected

active.

eight

read

four

in

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at

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map

at

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to

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latch

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signals

10

single-direction

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direction

quad-controlled
32K. The

registers,

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the

the

held

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function

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same

by

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select

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are

write

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data
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setup

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setup

Description

this

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the

stored

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PRT

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PASSTHRU

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character
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RD

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auxiliary

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the

to

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U408A)

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the

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the

portion

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that
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blink

computer

information
of

RAM

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used

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This

to

produce

the

NVRAM

the

portion

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display

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discussed

is

ORed

at

the

low

(U439).

memory

further

U426D

level

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with

The

main
operations
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Crystal

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14.784
undesired
to

the

C428

Inverter
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the

clock
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The

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circuit,
synchronization

fed

directly
This
rate.
(U424A)

oscillator

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biased

Y401

MHz

input

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C441

lJ.41.1D

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This

other

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allows

In

the

divides

negative

circuit.

prevents

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by
provides
clock

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buffers

necessary

circuits.

14.784

main

circuits.

to

the

the

video

main

the

clock

terminal.

resistors

positive

signal.

feedback

altering

impedance

The

the

MHz

processor

clock

dots

processor

14.784

circuit

Decoupling

the

the

high
current
other

high

clock

In

input

to

MHz

It

consists

R411

from

buffers

frequency

clock

the

clock

and

feedback

being

oscillator

matching

frequency

drive

signal

dot

of

be

shifted

Signal

1 1

controls

R412

capacitor

introduced

for

internal

signal

is

circuit,

clock

shift

circuit,

by

all

of

an

for

so

the

frequency.

for

the

clock

the

remaining

from

coupled

and

cirCUit,

register

out

at

a

D-type

a

factor

of

the

inverter

linear

inverter

C439

from

crystal

signal

to

U411

to

the

the

of

timing

operation.

prevents

the

Capacitors

and
portion

are

being

the

dot

video

the

signal

U415.

14.784

flip-flop

2

(U411A)

generates

output

circuit.

not

coupled

clock

timing

MHz

of

and

is