CRD8900-1 View Datasheet(PDF) - Cirrus Logic

Part Name

Description

MFG CO.

CRD8900-1

Highly-Integrated ISA Ethernet Controller

Cirrus Logic 

4.4.3 Status and Control Register Descriptions

CS8900

Register 0: Interrupt Status Queue (ISQ, Read-only)

Address: PacketPage base + 0120h

F-6

RegContent

5-0

RegNum

The Interrupt Status Queue Register is used in both Memory Mode and I/O Mode to provide the host with

interrupt information. Whenever an event occurs that triggers an enabled interrupt, the CS8900 sets the appropri-

ate bit(s) in one of five registers, maps the contents of that register to the ISQ register, and drives an IRQ pin

high. Three of the registers mapped to ISQ are event registers: RxEvent (Register 4), TxEvent (Register 8), and

BusEvent (Register C). The other two registers are counter-overflow reports: RxMISS (Register 10) and TxCOL

(Register 12). In Memory Mode, ISQ located at PacketPage base + 120h. In I/O Mode, ISQ is located at I/O

Base + 0008h. See Section 5.1.

BIT NAME

DESCRIPTION

5-0 RegNum

The lower six bits describe which register (4, 8, C, 10 or 12) is contained in the ISQ.

6

RegContent The upper ten bits contain the register data contents.

This register’s initial state after reset is: 0000 0000 0000 0000

48

DS150PP2

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