W83877TF Datasheet, PDF (127/154 Pages) Winbond – I/O chip disk drive adapter

W83877TF
CR31[7:4]
0000
0001
0010
0011
0100
0101
0110
0111
1000
None (default)
IRQ_A
IRQ_B
IRQ_C
IRQ_D
IRQ_E
IRQ_F
IRQ_G
IRQ_H
Mapped IRQ pin
While in the Serial IRQ mode (IRQMODS=1, CR31 bit 2), the above selection is invalid and all the
IRQ signal pins, from IRQ_A to IRQ_H, are all in tri-state. The SCI interrupt output is dedicated to the
SERIRQ pin. For the host controller to correctly sample the SCI interrupt, the SCI interrupt should be
programmed to appear in one of IRQ/Data Frame sampling periods.
In Serial IRQ mode, the definition of SCIIQS3-SCIIQS0 (bit 7-bit 4) is as follows:
SCIIQS3-SCIIQS0 (bit 7-bit 4): Select the IRQ/Data sampling period on the SERIRQ pin.
CR27[7:4]
0000
0001
0010
0011
0100
0101
0110
0111
1000
1001
1010
1011
1100
1101
1110
1111
IRQ/Data Frame Period
None
IRQ1
Reserved for SMI
IRQ3
IRQ4
IRQ5
IRQ6
IRQ7
IRQ8
IRQ9
IRQ10
IRQ11
IRQ12
IRQ13
IRQ14
IRQ15
Bit 3: Reserved.
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Publication Release Date: March 1998
Version 0.61