Sharp mz-800 Instrukcja Obsługi Pobierz pdf (Strona 32)

MZ-800

4-4. 8253 Programmable Interval

Timer

The 8253 makes

sound

generated

with

the

counter

#0

and internal

timer

is

operated

with

the

counters

#1 and

#2.

•

Counter

mode

#0

..... Square

waveform

generator

MODE3

#1 ..... Rate

generator

MODE2

#2

.....

Interrupt

on

terminal

counter

8253

(8255)

PC2

DD

D7

OUT 2

INT

I

I

DTO

DO

ClK

2

AD1

A1

OUT1

ADO

AO

ClK

1

HSYN

(PlO)

PA4

RD

OUTO

(PSG)

Audio·

in

RD

(8255)

PCO

WR

WR

ClK

0

CKMS (1.10

MHz)

C53

CE

GATE 0 53G

• The

counter

#0

counts

input

pulse

of

1.1

MHz,

divided

by

the

predetermined

rate (musical score

data)

to

generate

sound.

It

is connected

with

the

mixing

audio

amplifier

through

AUDIO-IN

of

the

sound

IC

(76489AN).

This

counter

output

is

gated

by

PC

of

the

8255

port

C,

and

the

counter

gate

is

controlled

by

001

of

$E008.

The

counter

#0

output

is also used

for

interrupt

control

INTO

and connected

to

A4

of

the

Z-80A PlO

port

A.

• The

counter

#1

counts

pulse

of

15.6

kHz

and gener-

ated a

pulse on OUT1 at

every

second. The

counter

#2

counts

pulses and makes OUT2

turned

high.

OUT2

outputs

becomes

INT

via

the

gate and is

connected

to

INT

of

the

CPU.

4-5. Printer interface

The Z-80A PlO is used

for

the

printer

interface. It has a

pair

of

8-bit

1/0

ports.

31

r

Do

D,

D,

Data

bus 1

8!

Ds

Ds

D7

{

BlA

CID

PlO

control

GE.

M1

10Ra

fill

+5V

GND

Interrupt

IEI

{

INT

control IEO

78/'-

p

,''0

A -

c'

Pin configuration

Ao

A,

A,

Aa

A.

As

pon

A

7

~

ARDY

ASTB

Ba

f

B,

B,

B3

B.

B

s

Pon

B

Bs

B7

E!HDYJ

BSTB

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