Ssm Vb1c User manual

VBle

·

Memory Mapped

:Video Board

Instruction Manual

INsrRIJCI'ION

MANUAL

SSM

t-lICROCCMPUTER

PROOOCTS,

INC.

2190

Paragon

Drive

San

Jose,

california

95131

Telephone:

(408) 946-7400

'lWX: 910-338-2077

Telex:

171171

DOD:

(408) 946-3644 (110 Baud)

TM

VBlC

is

a

tradanark

of

SSt1

Microcomputer

Products,

Inc~

Written

by

Malcolm

T.

Wright

Edited

by

Dan

Fischler

Illustrated

py

Judith

Sisko

@

1980

Sa.1

MICROCDMPUTER

PROWerS,

INC.

All

Rights

Reserved

Part

No.

MN0021

January

1982

1.0

INT.RODUCTION

2.0

ASSa.mLY

INSTmCl'ICES

2.1

Unpacking

2.2

Resistor

Installation

2.3

Diode

Installation

2.4

Socket

Installation

2.5

Capacitor

Installation

2.6

Transistor

Installation

2.

7

Crystal

Installation

2.8

Regulator

Installation

2.9

Coonector,

Beder

and switch

Installation

3.0

FUNcrIONAL ClIECK/IC

INSI'ALLATICN

3.1

Short

Test

3.2

Voltage

Check

3.3

Power

Resistor

Installation

3.4

Visual

Inspection

3.5

IC

Installation

4.0

SmTIl'G

UP

YOUR

VBlC

4.1

AcXlressing

4.2

64

or

32 Characters

per

Line

Selection

4.3

Graphics

or

Inverse

Video

Selection

4.4

Graphics

Patterns

4.5

Blanking/MSB Control

5.0

THEDRY

OF

OPERATION

5.1

General

Infornation

5.2

Sync Generation

5.3

Addressing

5.4

Picture

Formation

5.5

Power

Supplies

5.6

Blanking

6.0

OOFIWARE

6.1

Video Board Driver

6.2

Video Board Demonstration Routine

6.3

Graphics

Interface

Subroutine

6.4

DooOle

Graphics Demonstration

6.5

Video

Test

Routine

6.6

Memory

Test

Routine

7

.0

rmaJBLESHOCYrIN;

BINI'S

8.0

WARRANI'Y

i

APPENDIX:

Assembly Drawing

Parts

List

Schematic

(Insert)

ii

1.0

IHlKDJCI'Im

The

SSM

VB1C

provides

a memory mapped

video

display

for

any

S-lOO

bus

canp:ltible

microcanputer.

The

VB1C

features

such

capabilities

as

32

or

64

characters

per

line

(switch

selectable)

by

16

lines,

upper

and

lower

case

with

descenders,

Greek

characters,

graphic

symbols,

black-on-white

or

white-on-black

display,

7 x 9

character

matrix,

and

1K

on-board

RAM.

The

VB1C

is

fully

comFEltible

with

the

proposed IEEE 696

standard,

with

two

exceptions:

1)

the

VB1C

uses

the

01

clock

on

bus

25

instead

of

the

new

PSTVAL

signal1

and

2) when

the

CPU

reads

data

from

the

VBIC,

data

is

transferred

back

without

the

use

of

the

S~

and

PDBIN

signals.

We

suggest

that

you

read

this

entire

manual

before

either

starting

assembly

or

use

to

improve

your

understanding

of

the

board

and

make

its

set-up

and

use

that

much

easier.

RYrES:

The

VBIC

meets

the

following

IEEE 696

compliance

levels:

08,

M16,

NI,

T250,

we,

SH.

All

references

to

the

PC

board

assume

that

the

board

has

the

100-pin

connector

at

the

lower

edge,

and

the

component

side

(the

side

with

the

silk

screen)

is

facing

you.

Z-oo

is

a

trademark

of

ZIUX; INC., 10340

Bubb

Road, CUpertino,

CA

95014.

8080

and

8085

are

trademarks

of

INI'EL

CDRP.,

3065 Bowers Avenue,

Santa

Clara,

CA

95051.

1-1

Refer

to

the

Assembly

Drawing

in

the

APPENDIX

during

assembly

and

test

procedures.

2.1

UNPACKIN:;

[]

Unpack

and

check

each

of

the

~rts

against

the

PARTS

LIST

provided.

It

is

a

good

idea

to

arrange

the

parts

in

a

small

tray

or

box

to

allow

for

easy

identification

and

access

ibil

i

ty

during

assembly.

2.2

RESImoR

INsrALLATI~

NOTE:

Be

sure

that

all

resistors

and

diodes

are

flush

against

the

PC

board.

This

will

insure

proper

socket

installation.

DO

NO'!'

install

R21

and

R22

at

this

ti.me.

[]

Install

and

solder

SIX

(6)

100

ohm

(brown,

black,

brown>

resistors

at

locations

Rl,

2,

and

5-8.

]

Install

and

solder

TEN (10) 2.7K ohm

(red,

violet,

red)

resistors

at

locations

R4,

11-18,

and

24.

[]

Install

and

solder

ONE

(1)

lK ohm

(brown,

black,

red)

resistor

at

location

R23.

[]

Install

and

solder

ONE

(1) 220 ohm

(red,

red,

brown)

resistor

at

location

R3.

[]

Install

and

solder

TVD

(2)

470

ohm

(yellow,

violet,

brown>

resistors

at

locations

R9

and

10.

2.3

DIODE

INsrALIATION

[]

Install

and

solder

ONE

(1)

0070

germanium

signal

diode

at

location

CRl.

Use

caution

in

installing

this

component-the

banded

end

(+)

MUST

be

to

the

~

of

the

board.

2.4

SOCl<ET

INSl'ALLATION

RJ'l'E:

00

tUl'

install

integrated

circuits

until

SI8=ifiallly

instructed

to

do

so.

[]

Install

the

S,

14, 16,

and

24

sockets

on

the

printed

circuit

board.

Orient

I

towards

the

top

of

the

board

or

to

the

left,

as

applicable.

See

Figure

1

for

information

on

locating

1 on

each

socket.

CAO'l'IONl

DO

ROT

install

a

socket

at

location

81.

A

switch

will

be

installed

at

this

location

in

a

later

step.

2-1

Three

(3)

Nine (9)

Twenty-five

(25)

Three

(3)

SYMBOL~

INDEX

---

L

8-pin

sockets

at

tn-3

14-pin

sockets

at

U4,10-13,17,18,20,21

16-pin

sockets

at

06-8,14,19,22-29,31-42

24-pin

sockets

at

US

,15

,16

SOcket

'l'ypes

~

DD

I

NOEX-..

00

I

FIGURE

1

[]

When

all

sockets

are

inserted,

plaoo

a

pieoo

of

stiff

cardboard

over

the

sockets

to

hold

them

in

place

and

turn

the

board

over

to

expose

the

reverse

side.

[]

On

each

socket,

solder

1

and

the

diagonally

opposite

it

to

'tack'

(lightly

solder)

each

socket

in

place.

When

all

sockets

are

tacked

in

plaoo,

tum

the

board

over

and examine

each

socket

to

make

sure

it

is

flush

against

the

board.

If

needed,

reheat

the

pins

and

adjust

any

sockets

not

firmly

mounted.

[]

When

all

the

sockets

are

pro~rly

seated,

solder

the

remaining

pins

of

each

socket.

Do

not

overheat.

2.5

CAPACrroR

INSI'ALLATION

[]

Install

and

solder

TEN

(10) 0.1

uf

monolithic

capacitors

at

loca

tions

Cl,

2,

5-9,

and 11-13.

[]

Install

and

solder

ONE

(1)

47-56

pf

disc

capacitor

at

location

C4.

[]

Install

and

solder

ONE

(1)

.0033

uf

disc

cap;tcitor

at

location

C17.

[]

Install

and

solder

TWO

(2)

10

ufaxial

capacitors

at

locations

C3

and

CI0.

Use

caution

in

installing

these

components--c3

and

ClO

MUST

have

the

positive

(+)

em

to

the

RIGlr

side

of

the

board

[]

Install

and

solder

ONE

(1)

4.7

ufaxial

capacitor

at

location

C14.

USe

cantion

in

install

jog

this

0

-raonent-cl.4

MDsr

have

the

positive

(+)

end

to

the

LEFT

side

of

the

board.

2.6

TRANSISTOR

INSTALLATION

(]

Install

and

solder

ONE

(1) 2N3904

transistor

at

location

Ql.

Again,

use

caution

in

installing

this

component;

refer

to

Figure

2

for

proper

orientation.

Use

caution

that

the

lead

closest

to

the

bottoa

of

the

board

roES

HJT

touch

B8.

2-2

Top

View

TO

TOP

Of

,-OAR;)

FlquRE 2

2.

7 ffiYSI'AL

INSTALLATICN

[]

Install

and

solder

ONE

(1)

12.44

MHz

crystal

at

location

YI.

Two

holes

have

been

provided

on

either

side

of

the

crystal

to

solder

a

strap

over

the

crystal

to

hold

it

in

place.

Use a

resistor

lead

to

make

this

strap.

IX)

RJT

overheat

the

crystal.

2.8

REGJLA'IDR INsrALLATION

[]

Place

TW)

(2)

7805

regulators

on

the

board

so

that

the

mOlIDting

hole

in

the

regulator

is

in

line

with

the

hole

in

the

board.

Mark

the

leads

for

proper

bending

to

match

the

holes

in

the

board

(allow

for

bend

radius).

[1

Bend

the

regulator

leads

to

match

the

holes

in

the

board.

[]

If

available,

apply

thermal

compound

to

the

back

side

of

each

regulator

case

(the

side

that

will

contact

the

heats

ink)

•

Use

just

a

little

thermal

canpound.

Too

much

is

worse

than

none

at

alL

[1

Install

and

solder

TWO

(2)

7805

regulators

at

locations

U9

and

U30

so

that

the

following

order

results

from back

to

front:

screw,

PC

board,

heatsink,

regulator,

lock

washer,

and

nut.

Be

sure

that

the

regulators

and

heatsinks

sit

flat

on

the

board

and

then

solder

all

regulator

leads.

2.9

OONNECIDR,

HEADER

AND

SiI'lQI

INSTALLATlOO

[1

Install

and

solder

mE

(1)

4-pin

molex

connector

at

location

JI

such

that

the

short

pins

are

inserted

in

the

PC

board.

Be

sure

that

the

teflon

base

sits

flat

against

the

board.

[1

Install

and

solder

ONE

(1)

2-pin

molex

connector

at

location

J2

such

that

the

short

pins

are

inserted

in

the

PC

board.

Again,

be

sure

that

the

teflon

base

sits

flat

against

the

board.

[1

Install

and

solder

ONE

(1)

3-pin

header

at

location

EI-E3.

[]

Install

and

solder

ONE

(1)

8-position

DIP

switch

at

location

Sl.

Orient

the

switch

with

position

1

at

the

top

of

the

board.

At

this

point

the

only

parts

yet

to

be

IOOlIDted

are

the

two power

resistors

and

all

the

ICs.

00

OOT

INsrALL

'lHESE

PARTS

AT

'!HIS

TIME.

2-3

WARN:u.;l

00

OOT

INsrALL

OR

REMOVE

THE

BOARD

WITH

POWER

ON.

DAMAGE

'ID

'!HIS

AND

amER

BOARDS

CDULD

RESJLTI

3.1

SIDRr

TEST

[]

If

an ohmmeter

is

available,

measure

the

resistance

between

50

(negative

meter

probe)

and

1

(positive

meter

probe)

on

the

edge

connector,

and

verify

a

resistance

of

20 ohms

or

greater.

If

your

readiD]

is

below

20

obms,

check

your

board

for

possible

shorts.

3.2

VOLTAGE

OIECK

[]

AWly

power

(+8V

to

+10v)

to

the

board

by

plugging

into

the

computer

or

by

connection

to

a

suitable

power

supply

(with

power

turned

off).

Measure

the

outputs

of

the

+5V

regulators

(U9

and U30).

The

voltage

should

be

+5.0V

(+/-

0.2v).

If

the

regulator

doesn't

meet

this

test,

check

the

board

for

shorts

or

errors.

(See

the

figure

below

for

the

assignments

of

the

regulator.)

7805

+

5V

OUTPUT

CAUrIONl WHILE

IT

lIAS

IMlER

IIA.PAaI)

'ID US,

SIIRtED

~

BltVE

BEm

KlDm

ro

EIPUIE

wrm

RSSIBlB

I&JURt

ro

£rES

1H>

BAlm.

BE'l'I'ER

SAFE

iBM'

fDmY-KEEP

1IIJR

F.ACE

AM>

IIAIU)

QIAR

(F

mE

RIGlIA'ltE

SDE

(F

mE

mARD

IlllUX;

DIE INITIAL

RlWER:-UP

CI?

MJR

OOARD..

3.3

IQVER

RESISTOR

INsrALIATION

[]

Insert

and

solder

TWO

(2)

15

ohm

3-watt

power

resistors

at

locations

R2l

and

R22.

For

improved

cooling

and

to

prevent

the

PC

board

from

discoloring,

mOlUlt

these

two

resistors

off

the

board

about

118

inch.

3.4

VISUAL INSPEX:TION

[]

Now,

look

over

the

board

carefully.

Check

for

solder

bridges,

cold

solder

joints,

and

unsoldered

pins.

Also,

using

the

Assembly Drawing

in

the

APPENDIX,

check

for

improper

part

location

or

polarity.

A few

minutes

of

careful

inspection

could

save

hours

in

troubleshooting

later.

3-1

3.5

IC

INSl'ALLATION

[]

Refer

to

the

Assembly Drawinj

to

install

the

followinj

integrated

circuits.

BE

CBRTAIN

mid'

1 OF

BACH

Ie

IS

ORIERTED PROPERLY.

It

is

sometimes

helpful

to

bend

the

lead3

of

the

IC's SLIGll!LY inward

by

placing

the

circuit

on

its

side

and

applying

firm

pressure.

This

assures

that

the

leads

will

be

straight

and

makes

it

easier

to

install

the

device

in

the

socket.

[]

Install

the

following

Ie's

as

shown

in

the

Assembly Drawing:

[ ]

U4

[ ] Ul7

[ ] 018

[ ]

023,28,34,35,40,41

[ ]

U42

7486

74LS00

7432

74367

IJt18l3l

[]

The

following

Ie's

are

extremely

sensitive

to

static

electricity.

Avoid

touching

the

IC

leads

without

fir

st

touching

the

PC

board

to

make

sure

that

both

items

are

at

the

same

static

IX>tential.

[ ]

024,25,26,27

[ ]

036,37,38,39

2l02AIr-2

[]

The

VBlC

can

now

be

tested

as

a

standard

1K memory

board.

A memory

test

program

is

provided

in

Section

6.6

for

this

purIX>se.

Be

sure

to

set

the

DIP

switch

(51)

to

the

desired

setting

before

attempting

any

testing.

Refer

to

Section

4.1

for

information

on

addressing

your

board.

[]

Install

the

following

Ie's

as

shown

in

the

Assembly DrawiBJ:

[ ]

U1,2,3

[ ] U5,15

[ ] U6,7

[ ]

U8

[ ] 010

[ ]

011,12,13,20

[ ]

U14,22,32,33

[ ] 019

[ ] 021

[ ]

029,31

75451

74150

74157

74166

74504

7474

74193/74LS193

74153

7408

74161

[]

The

following

Ie

is

extremely

sensitive

to

static

electricity.

Avoid

touching

the

IC

leads

without

first

touching

the

PC

board

to

make

sure

that

both

items

are

at

the

same

static

potential.

[ ] 016

MCM66714

[]

The

VBlC

can

now

be

tested

for

proper

video

operation.

A program

is

provided

in

Section

6.5

to

display

the

ASCII

character

set

plus

the

64

different

graphic

characters.

3-2

4.0

SEIil'lJ.IG UP lOOR VBIC

4.1

ADDREEsnx;

The

VBlC

occupies

lK

bytes

of

the

address

space

of

the

computer.

By

setting

DIP

switch

Sl,

the

user

can

locate

his

VBlC

at

anyone

of

64

different

memory

locations.

Switch:

O~osed=O

OFF=Open=l

ADI'RESS

0OOO-03FF

0400-o7FF

0800-0BFF

OCOO-oFFF

Al.5

ON

lOOO-13FF

ON

•

·

>BOOO-B3FF

OFF

·

..

»EOOO-E3FF

OFF

•

..

FCOO-FFFF

OFF

Al4

ON

OFF

Al3 Al2

All

AlO

ON ON

ON

OFF

ON

(J\l

OFF

ON

ON ON

OFF OFF

ON

OFF

ON

OFF

ON

OFF

ON

OFF

OFF OFF

OFF

> Adiress used by

SSM

8080

Monitor

VI.O

in

2708

EPID1

»

A<Xiress

used by

SSf.1

Z-80

Mcnitor VI.lO

in

2716

EPRGt

4.2

32

OR

64

CHARAcrERS

PER

LINE

SELECrION

The

VBlC

has

the

capability

to

display

either

32

or

64

characters

per

line.

The

selection

is

made

by

setting

switch

1

position

2

to

the

desired

line

length.

64

characters/line

= switch

ON

or

closed

32

characters/line

= switch

OFF

or

open

4

..

3

GRAPHICS

OR

INVERSE

VIDOO

SELECl'IOO

The

VBle

is

switched between two

t~s

of

display

by

setting

data

bit

7

to

a 0

or

a

1.

The

display

mode

is

determined

by

the

setting

of

Sl-l

as

follows:

BIT

D7

o

1

o

1

'vm REV

1

'

GWm:<S

ON

OFF

DISPLAY

Alphanumerics

on

a black background

2x3

matrix

graphics,

black

background

Alphanumerics

on

a black background

Alpharnmerics on a

white

background

4-1

4.4

GRAmICS

PA'ITERNS

If

switch

51-1 (GRPH)

is

on

and

the

byte

you

are

writing

into

the

VBIC

has

the

most

significant

bit

(bit

D7)

set

to

a

one,

the

display

will

show a

graphics

pattern.

The

lower

6

bits

of

each

byte

will

display

as

a 2 x 3

matrix

on

the

video

display.

UIIER

SIX BITS

o

1

IIII.'1Ril1Y

white

black

The

data

bits

are

displayed

in

the

following

manner:

IlM'A

BIT

DO

Dl

D2

D3

D4

D5

4.5

BLANKIl{;/MSB

<DN'mOL

rosrr:roo

Upper

left

Middle

left

LcMer

left

tJI:per

right

Middle

right

Lower

right

The

VBIC

has

a

3-pin

header

used

to

control

the

default

value

of

the

most

significant

bit

of

data

read

into

the

video

display

during

a

blanking

operation.

During

reading

or

writing

to

the

VBIC,

the

address

lines

of

the

on-boord

memory

are

logically

tied

to

the

S-100 bus and

not

to

the

video

timing.

The

MSB

of

data

during

reading

or

writing

may

differ

from

that

which

would

have

been

displayed

under

normal

video

conbi

ttrol,

so

the

screen

will

"sparkle"

with

periodic

differences

between

old

and

new

characters.

The

MSB

can

be

forced

to

a

zero

value

during

reading

and

writing

to

give

a more

consistent

state,

rather

than

random,

by

using

the

3-pin

header.

•

Camect

El

to

E2

if

you want random.

• Connect

E2

to

E3

if

you want

the

MSB=O

(recantoonded

for

JOOst

applications.

4-2

5.1

GENERAL

INFORMATION

The

VB1C

video

interfa~

is

essentially

a oomputer memory combined

with

an

interface

circuit

that

connects

the

memory

to

a

video

monitor.

The memory

data

may

be

displayed

in

either

alphanumeric

form

using

the

internal

character

generator,

or

in

a

direct

form

(graphics).

Characters

may

be

presented

either

white-on-black

or

black-on-white,

if

the

graphics

mode

is

not

selected.

Mixing

characters

and

graphics

is

also

possible.

The

66714

character

generator

can

display

128

different

characters.

other

generators

with

different

character

sets

are

also

available

from Motorola

(and from

SSM

on

s~cial

volume

orders).

Sixteen

lines

of

characters

are

produced

and

either

32

or

64

characters

per

line

may

be

selected.

Total

memory

consists

of

eight

1024-bit

RAMs.

Ten

of

the

computer's

memory

address

lines

are

connected

to

these

RAMs

through

decoders,

allowing

the

computer

to

selectively

address

each

display

:fX)sition. The

canputer's

remaining

6

address

lines

are

used

to

set

the

starting

address

of

the

board

within

the

entire

memory

space,

as

determined

~

DIP

switch

Sl.

5.2

SYNC

GENERATION

Figure

3 shows

the

12.44

MHz

crystal

oscillator

feeding

two

counters,

031

and

U32.

Counter

U31

divides

the

12.44

MHz

signal

by

8

and

passes

the

resulting

1.5375

MHz

signal

to

U32

for

further

division

by

16.

The

DOT

ClOCK

is

a

square

wave

timing

signal

used

in

shifting

out

video.

The WAD

signal

is

a

pulse

occurring

once

every

8

DOT

CLOCKs.

Both

the

DOT

CLOCK

and

the

WAD

signal

are

selected

for

either

32

or

64

characters-per-line

operation.

If

the

'32/64'

switch

is

'OPEN',

the

6.22

MHz

from

U31

is

selected

to

be

the

OOT

CLOCK.

If

the

'32/64'

switch

is

'CLOSED',

12.44

MHz

from

the

oscillator

is

selected.

For

the

LOAD

signal,

'32/64'

switch

'OPEN'

(32

characters)

selects

a

777.5

KHz

signal,

and

'32/64'

switch

'ClOSED'

(64

characters)

selects

a

+5V

level.

The

!DAD

signal

is

modified

by

the

1.550

MHz

pulse

signal

from

the

output

of

UIO

10,

to

become a

series

of

narrow

pulses

at

either

777.5

KHz

(32

characters)

or

1.5550

MHz

(64

characters).

The

97.2

KHz

carry

signal

from

U32

7

is

the

input

for

the

horizontal

timing

circuit

shown

in

Figure

4.

Both

U11

and

U20

are

used

to

divide

the

97.2

KHz

from

U32

by

6

to

give

a

horizontal

blanking

signal

at

16.2

KHz.

U13

generates

a

delayed

hor

izontal

sync

pulse

from

U2l

3,

but

only

during

horizontal

blanking.

U20

develops

the

horizontal

drive

signal.

Waveforms

are

shown

as

aids

to

troubleshooting

in

Figures

3

thru

5.

In

Figure

5,

the

BIT

SELECTOR

CLOCK

(16.2

KHz)

goes

to

the

bit

select

counter

U29. The

outputs

from

U29

give

the

row

select

address

for

the

character

generator.

When

address

1110

2

is

reached,

U29

is

loaded

with

00002

on

the

pulse

to

start

a new

cycle.

The

load

signal

is

a

negative

pulse

at

1079.9

Hz

which

is

sent

to

Ul2 and

vertical

line

oounter

U33.

In

addition

to

4

bits

of

the

RAM

address,

U33

puts

out

negative

pulses

at

60

Hz

on

CY.

U12

derives

negative

pulses

at

60

Hz

for

both

VERT

5-1

~---------e----------------'-----------------~5VGTE

10

5

CARRY

U32

97.2KHZ

C4

YI

'------4HD~-------.

12.4 4 MHz t

5V

~.L-::L-...;:.L.::::J:.::.a....:.:..L!!:L...::J...,

388.7

KHZ

DOT

CLOCK

LOAD

UI0,

4 - - - - -

6.22NHZ

-----

(+2)

U31

I PIN 15 n n n n

fL-

1.555MHZ

(+8)

U32,

PIN 3

777.5KHZ

(+16)

LOAD:

S W

64

32

OPEN n n

777.5KHZ

LOAD

~S

W

64

32

CLOSED n n n n

fL-

1.555

MHZ

1et71¥

1/-1$-77

FIGURE

3

/~>cI

8-.:11-,9::)

;>------

-----------+--f--..--...

HORZ.

SYNC

5VGTE

~_---I13

::> .

__

.

____

u

______

_

U32,

2

(388.7

KHZ)

U32,

PIN 7

(91.2KHZ)

U32,

PIN7

U32,CARRY

U11,

PIN 8

R

BIT

SELECTOR

CLOCK a

HORZ.

DRIVE

HORZ.BLANK

HORZ.

BLANK

97.2

KHZ

L

48.159

KHZ

U21,

PIN 3

----~!I~----~II

~

I I

u.HOx.R=Z,-,

~8J.y..,.N-",C'--

______

~--L...I1

I 15.1".

18.

2 KHZ

I I

013,

15

I I

U11,PIN

15

U28,

PIN.

.::.:Hc;:O'-'-'R=Z=

•

...:8~L"-'A~N=K

_____

--IF

28.8,..

==---I~

______

'8.2

KH

Z

U28,

PINe

H

ORZ.

DRIVE

FIGURE

4

5-2

2

11

12

U:3:3,

PW

5 I I I I I I I

U12, PIN 6 U

VERT.

DRIVE

U

:33,

PlN12

I

VERT.

BLANK

LJ

FIGURE

I I I I I

1079.9

HZ

60

HZ

60

HZ

60

HZ

69

HZ

5

VERT. DRI VE

VERT.

BLANK

•

BLANKING

16.2

KHZ

BIT

SELECTOR

CLOCK

'}tT1V

If-IS-77

/".,/

{l-8'-9J

DRIVE

(1

ms

pulse

w

idthl

and VERr

BLANK

(2

ms

pulse

width).

VERI'

BLANK

and

HORIZ

BLANK

are

combined

by

an

AND

gate

to

give

a

composite

BLANKIK;

signal.

The

other

6

bits

of

RAM

address

come

from

counters

U14

and

U22

which

are

reset

by

HORIZ

BLANK.

U22's

clock

is

the

lOAD

signal

from

Figure

3.

5.3

ADDREESnG

The

eight

l024-bit

RAMs

are

addressed

by

the

oomputer

using

address

lines

AO

thru

A9.

Address

lines

AlO

thru

A15

form

a

prefix

to

specify

the

board's

address.

This

6

bit

prefix

is

set

by

switch

81

plsitions

3

thru

8;

U42

compares

the

address

sent

by

the

computer

with

the

setting

of

the

switch.

If

the

address

matches,

U42

9

(SELECT)

goes

low,

which

actuates

the

10

address

gates

(AO

thru

A9),

the

output

gates

(DIO

thru

DI7),

and

the

write

gate

U17.

When

the

SELECT

signal

is

low,

it

also

turns

off

the

output

gates

of

counters

U14, U22,

and

U33.

With

the

VBle

memory

logically

tied

to

the

8-100

bus,

the

computer

can

store

the

data

in

the

video

board

memory

to

be

displayed.

When

the

address

from

the

oomputer

is

no

longer

Valid,

the

~

line

goes

high

and

the

memory

is

isolated

again.

5-3

5.4

PIcruRE

FORMATION

When

in

the

normal

character

display

mode,

the

VBIC

memory

is

continually

addressed

by

colUlters

U14,

022,

and

033. The memory makes

available

an B-

bit

data

word

for

each

location

addressed.

Only

7

bits

go

into

the

character

generator

to

specify

a

character,

or

into

the

mul

tiplexers

U5

and

U15

for

graphics

output.

The

output

of

the

character

generator

and

the

output

of

the

graphics

multiplexers

are

sent

into

two

data

selectors,

U6

and

U7.

If

the

GRAPHICS

signal

is

low,

U6

and

tJ7

p:lss

the

graphics

data

from

US

and

U15.

If

GRAPHICS

is

high,

U6

and

U7

pass

the

output

of

the

character

generator.

In

either

case,

the

output

of

U6

and

U7

is

loaded

into

parallel-in/serial-out

shift

register

UB.

The

data

is

then

shifted

out

to

the

display

monitor.

The

eighth

bit

(D7)

of

VBIC

memory

is

a

control

bit

whose

function

is

determined

by

the

VID

REV/GRAPHICS

switch

(Sl-l).

When

the

switch

is

OPEN,

GRAPHICS

is

high

and

the

output

of

the

character

generator

goes

into

parallel-in/serial-out

shift

register

UB.

Data

bit

D7

turns

the

video

reverse

on

or

off

by

setting

U13.

This

controls

the

VIDEO

REVERSE

signal

through

U2.

When

VIDro

REVERSE

is

high,

U4

inverts

the

output

which

produces

a

reversed

video

effect

on

the

ronitor.

If

the

VID

REV/GRAPHICS

switch

is

CIDSED,

the

VIDEO

REVERSE

signal

is

low,

allowing

the

output

of

UB

to

pass

with

no

inversion.

Data

bit

D7

directly

controls

the

GRAPHICS

signal.

If

GRAPHICS

is

high,

the

character

generator

output

is

selected;

if

GRAPHICS

is

low,

the

graphics

data

is

selected.

5.5

IQ1ER

SUPPLIES

A

single

+5

volt

supply

is

used

to

operate

the

VBIC.

The

standard

S-IOO

voltage

of

+BV

to

+lOV

is

regulated

~

two

7B05

regulators

to

provide

the

proper

voltage

on

the

board.

R21

and

R22

are

power

resistors

used

to

keep

the

power

dissip:.\tion

low

in

the

regulators.

The

typical

current

drain

is

1.3A.

5.6

BLANKING

Blanking

is

performed

on

the

VBIC

during

every

CPU

read

or

write

operation

to

the

video

board's

address.

U4

11

goes

to

a

logic

one

each

time

the

VBIC

is

addressed.

U4

11

is

buffered

by

one

inverter,

UIO

pins

12

and

13,

to

drive

an

RC

timer

formed

by

R24

and

C17.

The

inverter

UIO

12

provides

a

blanking

signal,

with

R24

and

C17

providing

a

turn-off

delay

for

increased

blanking

time.

Blanking

is

used

on

the

VBIC

by

forcing

the

video

display

to

black

during

CPU

accesses.

The

shift

register

U8

is

cleared

(set

to

black

·video)

during

blanking.

C17

is

discharged

and

U13

will

be

set

if

jumper

E2

to

E3

(see

Section

4.5)

has

been

installed.

When

the

blanking

signal

is

removed (UI0

12

goes

high),

C17

slowly

charges

to

a

logic

one

level

and

maintains

a

clear

to

U8

for

an

additional

time

period.

5-4

6.0

~

The

following

4 programs

are

provided

for

use

with

the

VBlC:

1.

Video Board

Driver

2.

Video Board

Driver

DEmonstration

Rrutine

3.

Graphics

Interface

Subroutines

4.

Doodle

Graphics

Denonstration

a.

All

4 programs assume

the

VBlC

is

addressed

at

EOOO-E3FF.

This

may

be changed

by

altering

the

value

to

which 'VID'

is

EX:Uated.

b.

All

programs

are

written

in

8080

assembly

language

and

are

executable

on a Z-80, 8085,

and

the

8080.

Two

other

programs

are

provided

for

initial

checkout

of

the

VBIC:

1.

Video

Test

Routine

2.

Memory

Test

Routine

NOTE:

These two programs assume

that

the

VBlC

is

addressed

at

EOOO-

E3FF.

In

the

Video

Test

Routine

this

may

be

changed

by

altering

the

value

to

which

'VID'

is

EQUated.

In

the

Memory

Test

program,

'SI'ART'

specifies

the

beginning

of

VBle memory and

'MEND'

specifies

the

end.

6.1

VIDEO

BOARD

DRIVER

This

is

a

complete

driver

routine

for

the

VBIC,

including

cursor

control,

clear

screen,

carriage

return,

line

feed,

and

cursor

addressing.

The

driver

may

be

located

in

ROM

or

RAM,

but

three

bytes

pointed

to

by

VDPTR

and

VDHLD

must

be

in

RAM.

Characters

to

be

output

are

expected

in

the

C

register.

6-1

SSM VB1C User manual

Popular Computer Hardware manuals by other brands