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Power-On Routine

The

following activities take place when power

first applied to

the

keyboard.

Power-On Reset

The

keyboard logic generates a

'power-on

reset' signal (POR)

when

power

first applied to the keyboard.

POR

occurs during

150

milliseconds to 2.0 seconds from the time power

first

applied to the keyboard.

Basic Assurance Test

The

basic assurance test (BAT) consists of a keyboard processor

test, a checksum of the read-only memory (ROM), and a

random-access memory (RAM) test. During the BAT, activity on

the

'clock'

and

'data'

lines

ignored. The BAT takes from 300

500

milliseconds. This

in addition to the time required by

the

PORe

Upon

satisfactory completion of the BAT, a completion code (hex

AA)

is sent to the system, and keyboard scanning begins. If a

BAT

failure occurs, the keyboard sends

error code to the

system. The keyboard

then disabled pending command input.

Completion codes are sent 450 milliseconds to 2.5 seconds after

POR,

and between

300

and 500 milliseconds after a Reset

command

acknowledged.

Immediately following POR, the keyboard monitors the signals on

the

keyboard

'clock'

and

'data'

lines and sets the line protocol.

lOl/102-Key

Keyboard 4-25

Brand	IBM
Model	XT 5160
Category	Desktop
Language	English

IBM XT 5160 User Manual

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IBM XT 5160 Specifications

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