System Board Pos Register 3 (Hex 0103); System Board Pos Register (Hex 0103) - IBM Personal System/2 50 Technical Reference

Bit 2
When this bit and bit 0 are set to 1, the system board
serial port is enabled.
Bit 1
When this bit and bit 0 are set to 1, the diskette drive
interface is enabled.
Bit 0
When set to 1, this bit allows bits 4, 2, and 1 to enable and
disable their respective devices. When set to 0, this bit
disables the diskette drive interface, system board serial
port, and system board parallel port, regardless of the
state of bits 4, 2, and 1.
System Board POS Register 3 (Hex 0103)
With the system board in setup, this register controls the system
board memory.
Bit Function
7 - 1 Reserved
o
Enable System Board RAM
Figure 2-6. System Board POS Register (Hex 0103)
Reserved.
Bit 7-1
Bit 0 When set to 1, this bit enables the system board memory.
When set to 0, this bit disables the memory. All system
board memory is enabled or disabled by this operation.
Model 50 POS 2-9