W83977AF Information Storage Devices, Inc, W83977AF Datasheet - Page 139

• Manufacturer Part Number: W83977AF
• Description: W83877TF Plus Kbc, Cir, RTC
• Manufacturer: Information Storage Devices, Inc

CR74 (Default 0x04)
CRF0 (Default 0x3F)
Bit 7-3 : Reserved.
Bit 2-0 : These bits select DRQ resource for Parallel Port.
Bit 7 : PP Interrupt Type:
Bit [6:3] : ECP FIFO Threshold.
Bit 2-0 Parallel Port Mode (CR F1 PRTMODS2= logical 1)
Not valid when the parallel port is in the printer Mode (100) or the standard & Bi-directional
Mode (000).
= 1
= 0
= 100 Printer Mode (Default)
= 000 Standard and Bi-direction (SPP) mode
= 001 EPP-1.9 and SPP mode
= 101 EPP-1.7 and SPP mode
= 010 ECP mode
= 011 ECP and EPP-1.9 mode
= 111 ECP and EPP-1.7 mode.
0x00=DMA0
0x01=DMA1
0x02=DMA2
0x03=DMA3
0x04-0x07= No DMA active
Pulsed Low, released to high-Z .
IRQ follows nACK when parallel port in EPP Mode or [Printer, SPP, EPP] under ECP.
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W83977F/ W83977AF
Publication Release Date: March 1998
PRELIMINARY
Revision 0.58