Megatel Quark/100 Specifications download pdf (Page 28)

The

Z8OB's

Interrupt input line

awn

is avai lable

the Peripheral

Expansion

Bus

allow external devices to generate interrupts to the

Z8OB.

power-on

reset output (active

low)

is also provided to reset external peripheral devices. Finally, a

decoded

active-low chip-

select line responding to

1/0

addresses

between

and

FF(hex)

created on-board

and

can

used

to select a single external peripheral device, or to qualify the decoding of

some

of the

address lines for several external chip-select lines.

The

Power-on-reset

output

the Peripheral

Expansion

Bus

active-low buffered

reset line

which

should

used

resetting external peripheral devices.

Note

that

808D-type

devi

ces

requi

active-high reset signal,

the

POR

line

would

have

inverted

service these devices.

ease

timing

requirements

for

interfacing

external

peripheral

devices

the

six

megahertz

CPU,

four wait

states

(T-states) are

added

all

zao

1/0

machine

cycles. This

over

and

above the standard

extension

mod-4

cycles

for

any

memory

cycle.

Thus

1/0

instruction

which

might

require, for example,

cycles

would

first

extended

cycles,

and

then further extend to

cycles. This allows

"AU-version

(1.5MHz)

peripheral devices to

used. Because of

the

exact

rule

used

for

wait-state

insertion,

Table

XII

should

consulted for precise instruction timing information.

several external peripheral devi

ces

are to be connected to the

QUARK's

Peripheral

Expansion

Bus,

the

Bus

is to

extended

any

significant distance,

recommended

that

the address, data,

and

control lines being

used

be buffered

TIL

drivers.

Two

TTL

packages

are sufficient for

this

purpose

only

8080-

or only 6500/680D-type peripheral chips are used;

both

types are

employed

then

additional buffer

necessary, unless five or fewer address

lines are

reCJ.Iired.

application rote

use

this

bus

available.

Megatel

Computer

Technologies Toronto,

Canada

Page

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Megatel Quark/100 Specifications Page 28

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