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Power-On Routine
The following activities take place when power is first applied to
the keyboard.
Power-On Reset
The keyboard logic generates a 'power-on reset' signal (POR)
when power is first applied to the keyboard. POR occurs during
150 milliseconds to 2.0 seconds from the time power is 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 is ignored. The BAT takes from 300
to 500 milliseconds. This is 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 an error code to the
system. The keyboard is 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 is 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
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