IBM Personal System/2 60 Technical Reference page 20

Setup functions respond to I/O addresses hex 0100 through 0107 only
when their unique setup signal is active. The following precautions
must be taken before setting individual bits in the POS registers.
System Board Video Subsystem Setup:
• Bit 5 in the System Board Enable/Setup register (hex 0094) must
be set to 0 to place the system board video into the setup mode.
I
• Bit 3 in the Adapter Enable/Setup register (hex 0096) must be set
to 0 to avoid driving a 'setup' signal to an adapter.
• Bit 7 in the System Board Enable/Setup register (hex 0094) must
be set to 1 to avoid driving a 'setup' signal to other system board
functions.
Adapter Setup:
• Bit 3 in the Adapter Enable/Setup register (hex 0096) must be set
to 1 to allow adapter setup.
• Bit 5 in the System Board Enable/Setup register (hex 0094) must
be set to 1 to avoid driving a 'setup' signal to the Video
Subsystem.
• Bit 7 in the System Board Enable/Setup register (hex 0094) must
be set to 1 to avoid driving a 'setup' signal to a system board
function.
Other System Board Setup:
• Bit 7 in the System Board Enable/Setup register (hex 0094) must
be set to 0 to allow setup of other system board functions.
• Bit 3 in the Adapter Enable/Setup register (hex 0096) must be set
to 0 to avoid driving a 'setup' signal to an adapter.
• Bit 5 in the System Board Enable/Setup register (hex 0094) must
be set to 1 to avoid driving a 'setup' signal to the Video
Subsystem.
2-4 Model 60 POS