IBM 6580 User Manual

Key
Pressed
(First)
Pad
To System Electron ics
Figure 5-9. Keyboard Data Flow
BASIC ASSURANCE TEST (BAT)
A Power on Reset (POR) of the system
will automatically start the keyboard
Basic Assurance Test (BAT) and perform
wrap tests on the keyboard adapter
circuits of the system card.
The keyboard BAT verifies the keyboard
microprocessor is operating correctly.
The keyboard notifies the system
processor of the keyboard status by
transmitting a specified sequence of
two bytes of data. Successful com-
pletion of the BAT is necessary for
the keyboard to proceed with normal
system operation (Figure 5-10).
A third byte containing the keyboard
ID is also transmitted to provide con-
figuration information.
System Power-an-Reset
BAT signal to keyboard microprocessor
BAT
self-test of keyboard microprocessor
BA T com pletion codes transm itted
System electron ics accepts data byte codes
Keyboard 1.0. Transmitted
Keyboard Operational
Figure 5-10. BAT Sequence
CHARACTER BUFFER
The keyboard contains a four character
buffer to temporarily store data until
the system electronics is ready to
receive it. An overrun error occurs
if the four buffer positions are
filled and an additional character is
keyed. The additional character and
the fourth position character will be
lost and the overrun error character
will be entered into the fourth posi-
tion of the buffer.
KEYBOARD IDENTIFICATION (10)
On success ful completion of the key-
board BAT, a keyboard identification
(ID) data byte is sent to the system
by the keyboard. The position of the
logic card ID 'jumpers (shown in
Figure 5-14) determine the keyboard ID
byte.
The transmission of this byte signals
the system electronics the completion
of the keyboard BAT and identifies the
keyboard arrangement. The keyboard
then enters the normal operating mode.
5-8 IBM Displaywriter Product Support Manual

IBM 6580 Specifications

General

Brand	IBM
Model	6580
Category	Desktop
Language	English