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 F. Ohland, Peter H. Wendt, David L. Beem, William R. Walsh, Tatsuo Sunagawa, Tomáš Slavotínek, Jim Shorney, Tim N. Clarke, Kevin Bowling, and many others.

Ardent Tool of Capitalism is maintained by Tomáš Slavotínek.
Last update: 20 Jan 2024 - Changelog | About | Legal & Contact