ACT apricot - Page 221

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KEYBOARD

register

is

used

either

for

selecting

characters

to

be

displayed or

writing

the

data

for

the

character shapes

that

are

held

in

RAM

rather

than

in

the

character

generator

ROM.

The

following

functions

are available for

the

MicroScreen:

1.

Text

display

in

two

lines

of forty characters.

2.

Absolute

cursor

addressing. '

3. Move

cursor

left

(non-destructive).

4.

Move

cursor

right

(non-destructive).

5.

Clear

display.

6.

Display on/off.

7.

Cursor

on/off.

8.

Display

time,

day

and

date.

The

character

set

is

shown

in

a

table

at

the

end

of

the

chapter,

the

codes

shown

are

those

that

are

actually

sent

to

the

Keyboard

and

do

not

correspond

to

those

that

are

sent

to

the

MicroScreen device

in

MS-DOS.

The

cursor

is a single

non

blinking

underline

that

is

displayed (when enabled)

where

the

next

character

sent

will

be displayed.

The

physical cursor address for

line

one of

the

display are

o

to

27H

and

for

line

2

40H

to

67H.

These

are

mapped

into

the

range

80H

to

CFH

(i.e.

line

1

80H

- A7H,

line

2

A8H-

CFH).

The

date

and

time

are read

out

of

the

clock IC

and

displayed

in

the

top

right

side of

the

MicroScreen

when

the

appropriate

command

is received by

the

Keyboard.

The

time

is

updated

every

second

while

it

is

displayed

without

the

cursor

position

being disturbed.

The

format

on

the

screen

for

the

date

and

time

is:

DAY

DD

MMM

YY

HH:MM:SS

The

LED's are

controlled

by

sending

two

characters

to

the

Keyboard,

the

LED prefix followed

by

a

data

character

in

the

range 00

to

FF.

A

bit

set

indicates

that

the

LED

will

be

switched

on

and

a

bit

clear

that

it

will

be

extinguished.

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Service Manual305 pages