ACT apricot - Keyboard Firmware

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KEYBOARD

KEYBOARD FIRMWARE

The

Keyboard firmware is a

real-time

interrupt

driven

operating system.

The

main

scheduler

is

split

into

two

parts, one

which

is

continuously

executed

and

the

other

which

is

only

executed every 10ms. Each

part

carries

out

several operations,

the

first

part

scans

the

receive character

buffer for characters received

and

processes

any

that

have

not

previously

been

dealt

with,

it

also sends X -on

when

appropriate

and

polls

the

mouse

port

for

the

mouse

releasing

the

data

link.

The

second

part

is

executed

after

the

timer

interrupt

routine

has

be-en

executed

( every 10

ms

,.

If

the

time

and

date are being displayed

then

it

is

updated

if

necessary. After

this

the

Keyboard is

scanned

for

any

changes

to

the

key

positions.

If

the

Keyboard

has

not

received a reset

acknowledge

character

since

power

up

or

switching

into

diagnostic

mode

a

reset

request

character

is

transmitted

if

100

ms

has

elapsed since

the

last

one

was

sent. In

this

phase

all

other

characters are ignored.

This

main

routine

is

interrupted

by

several events.

The

first

is

reception

of characters from

the

System

Unit,

the

second

is

the

UAR

T

transmitter

being empty,

when

there

are characters

to

send

to

the

System

Unit.

Other

sources are

the

10

ms

timer

maturing,

or

the

mouse

requesting

the

bus,

if

it

is enabled.

The

processing of characters received from

the

System

Unit

is

split

into

two

parts.

The

first is all

the

commands

that

do

not

directly affect

the

LCD.

These

are of

the

form

ExH

and

are

processed

by

means

of a

jump

table,

their

effect

is

shown

in

the

System

Unit

to

Keyboard table

and

the

relevant

section.

When

the

appropriate code is received

the

processor diagnostics are executed.

There

are

two

tests, a

ROM

checksum

and

a RAM self address test.

If

both

of

the

tests

are passed

then

FBH is returned.

If

the

ROM

test

failed

then

E9H is

returned.

If

the

RAM

test

passed

but

the

ROM

test

failed

the

sequence E9H,

FBH

is

returned.

If

the

ROM

test

passes

but

the

RAM

test

fails

then

BOH

is sent,

if

both

fail

then

E9H,

BOH

is

sent.

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Other manuals for ACT apricot

Service Manual305 pages