Group 2 POS Registers

Group 2 POS Register 2 (Hex 0102)
Group 2 POS Register 3 (Hex 0103)
Group 2 POS Register 4 (Hex 0104)


Group 2 POS Register 2 (Hex 0102)

This register configures the system board serial ports.

+-----------------------------------------------+
|  7  |  6  |  5  |  4  |  3  |  2  |  1  |  0  |
|-----------+-----+-----+-----------+-----+-----|
| Reserved  |EN_B |EN_A | Reserved  |IR_B |IR_A |
+-----------------------------------------------+
 EN_B: Enable serial port B
 EN_A: Enable serial port A
 IR_B: Serial port B interrupt
 IR_A: Serial port A interrupt

EN_B, EN_A These bits enable and disable serial port B and serial port A (bit 0 in POS Register 2 of group 1 must be 1 before the serial ports can be enabled). When the bit is set to 1, the corresponding serial port is enabled; when it is set to 0, the serial port is disabled.

IR_B, IR_A These bits select the interrupt signal used by serial port B and serial port A. When the bit is set to 1, the corresponding serial port uses IRQ4; when the bit is set to 0, the serial port uses IRQ3.


Group 2 POS Register 3 (Hex 0103)

This register is used to select the address range for the serial port.

+-----------------------------------------------+
|  7  |  6  |  5  |  4  |  3  |  2  |  1  |  0  |
|-----------------------+-----------------------|
|    Port B Address     |     Port A Address    |
+-----------------------------------------------+

Address Each four-bit field selects the address assignments for serial port A or serial port B. The following figure shows the addresses associated with each assignment.

Serial Port Addresses

Address Sel.Address (hex)
FieldAssignmentCompatibleEnhancedARB Level
0 0 0 0Serial 103F8-03FF83F8-83FF4620
0 0 0 1Serial 202F8-02FF82F8-82FF4621
0 0 1 0Serial 33220-3227B220-B2274623
0 0 1 1Serial 43228-322FB228-B22F4623
0 1 0 0Serial 54220-4227C220-C2274624
0 1 0 1Serial 64228-422FC228-C22F4625
0 1 1 0Serial 75220-5227D220-D2274626
0 1 1 1Serial 85228-522FD228-D22F4627
1 0 0 0Serial 93A20-3A27BA20-BA274628
1 0 0 1Serial 103A28-3A2FBA28-BA2F4629
1 0 1 0Serial 113A30-3A37BA30-BA37462A
1 0 1 1Serial 123A38-3A3FBA38-BA3F462B
1 1 0 0Serial 133A80-3A87BA80-BA87462C
1 1 0 1Serial 143A88-3A8FBA88-BA8F462D
1 1 1 0Serial 153A90-3A97BA90-BA97462E
1 1 1 1Serial 163A98-3A9FBA98-BA9F462F


Group 2 POS Register 4 (Hex 0104)

Version level of the I/O chip containing the serial port controllers.

+-----------------------------------------------+
|  7  |  6  |  5  |  4  |  3  |  2  |  1  |  0  |
|-----+-----------------+-----------------------|
|  R  |     Version     |         Reserved      |
+-----------------------------------------------+

Version The version field is a 3-bit field that indicates the version level of the I/O chip containing the serial port controllers.

Content created and/or collected by:
Louis Ohland, Peter Wendt, David Beem, William Walsh, Tatsuo Sunagawa, Jim Shorney, Tim Clarke, Kevin Bowling, Tomáš Slavotínek, and many others.

Ardent Tool of Capitalism - MAD Edition! is maintained by Tomáš Slavotínek.
Last update: 25 Nov 2022 - Changelog | Legal Info & Contact