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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.
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.
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