ACT apricot - Expansion Board Layout Detail

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EXPANSION SLOTS

The

1/0

space is divided

into

two

ranges to cater for

the

varying access

times

of peripheral devices. In

the

lower

address range

BaH

to F7H, 1 processor

wait

state

is

automatically

inserted

for

any

110 read

or

write.

In

the

" upper address range

lOOH

to

lFFH,

no

wait

states

are

inserted.

Fast peripherals (access

times

of

350

ns

or less)

should

therefore be

located

within

the

range

lOOH

to lFFH. Slower

peripherals (access

times

from 350

to

550ns)

should

be

located

within

the

range

SOH

to

7FH. Peripherals

with

even

slower access

times

can

be

sited

within

either

range,

but

must

make

use

of

the

IRDY

input

to

extend

the

processor

cycle.

For

memory-mapped

devices,

the

input

MRDY can be

utilised

to

insert

wait

states

to

extend

a processor

memory

cycle.

Expansion Board Layout

Detail

The

dimensions

and

layout

details for

an

Expansion Board

are detailed

on

the

diagram

on

the

next

page.

The

uppermost

view

illustrates

the

overall board

dimensions

and

the

location

of

the

connector.

The

middle

projection

provides a different

view

of

the

connector

and

details

the

maximum

height

available for

components

mounted

on

the

board.

The

lower

illustration

details all

the

drilling

requirements

for

the

printed

circuit

board

and

the

board

area available.

NOTE:

The

3.S5

mm

diameter

holes located

in

three

corners of

the

board

are

only

required

on

expansion cards

made

up

of

two

boards,

in

the

form of a

"sandwich

"(i.e. a

main

board

fitted

with

the

expansion connector,

and

a

piggyback board separated from

the

main

board by spacers)

..

In

this

situation,

the

three

holes

can

be

used

as general

purpose tooling holes

and

also as screw holes for

the

spacer

fixings.

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Other manuals for ACT apricot

Service Manual305 pages