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System Board Enable/Setup Register (Hex 0094)
This is a read/write register; all bits in this register default to 1
(enabled).
Bit
Function
7
Enable/-Setup System Board Functions
6
Reserved
5
Enable/-Setup Video Subsystem
4 - 0
Reserved
Figure
2-3. System Board Enable/Setup Register (Hex 0094)
Bit 7
When this bit is set to 0, various system board I/O
functions are placed in the setup mode. The diskette drive
controller, serial port, and parallel port are controlled
through System Board POS Register 2 (hex 0102). The
memory is controlled through System Board POS Register
3 (hex 0103).
When this bit is set to 1, the system board functions are
enabled.
Bit 6
Reserved.
Bit 5
When this bit is set to 0, the video subsystem is placed in
the setup mode and controlled through POS Register 2
(hex 0102). When set to 1, and bit 0 in hex 0102 is set to 1,
video is enabled.
Bit 0 of POS Register 2 is the video enable bit. When this
bit is set to 0, the video subsystem does not respond to
commands, addresses, or data. If video is being
generated when the video enable bit is set to 0, the output
is still generated. For information on BIOS calls to enable
or disable the video, see the IBM Personal System/2 and
Personal Computer BIOS Interface Technical Reference.
Note: When the video is disabled, access to the video
DAC registers is disabled.
Bits 4 - 0
Reserved.
Model 60 POS
2-7
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