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INTRODUCTION

The

keyboard software is designed

to

handle

all

communications

between

the

serial keyboard,

real-time

clock,

mouse

and

the

MS-DOS 2.0

Operating

system.

APPLICATIONS INTEREST

Keyboard Lookup Table

The

keyboard

lookup

table is

used

by

the

BIOS

to

obtain

the

code(s) for

each

key

on

the

keyboard.

The

first 104 words

(208 bytes) is

the

data

for

the

unshifted

mode,

the

next

104

words is

the

data

for

the

shifted

mode,

the

next

104 words is

the

data

for

the

control

mode. After

this

there

are 400 bytes

of

string

space

which

is

dynamically

allocated for

the

string

keys.

The

table

in

all

consists

of S68 words.

Each

word

in

the

table

provides

the

following

information:

Bi

t

15

=0

Bi

t

15

= 1

Bi

t

14

=0

Key produces a

string

of characters,

in

this

case,

bits

0 - 14 provide a IS-bit

string

pointer

to

a

string

held

in

memory.

Key is a

normal

non-string

or special

key

and

is

handled

in

the

normal

way.

Key is

not

a special

key

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Other manuals for ACT apricot

Service Manual305 pages