W83977AF Information Storage Devices, Inc, W83977AF Datasheet - Page 94

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

5.2.5 EPP Data Port 0-3
These four registers are available only in EPP mode. Bit definitions of each data port are as follows:
When accesses are made to any EPP data port, the contents of DB0-DB7 are buffered (non-
inverting) and output to the ports PD0-PD7 during a write operation. The leading edge of IOW causes
an EPP data write cycle to be performed, and the trailing edge of IOW latches the data for the
duration of the EPP write cycle.
During a read operation, ports PD0-PD7 are read, and the leading edge of IOR causes an EPP read
cycle to be performed and the data to be output to the host CPU.
5.2.6 Bit Map of Parallel Port and EPP Registers
Data Port (R/W)
Status Buffer (Read)
Control Swapper (Read)
Control Latch (Write)
EPP Address Port R/W)
EPP Data Port 0 (R/W)
EPP Data Port 1 (R/W)
EPP Data Port 2 (R/W)
EPP Data Port 3 (R/W)
REGISTER
BUSY
PD7
PD7
PD7
PD7
PD7
PD7
7
1
1
7
ACK
PD6
PD6
PD6
PD6
PD6
PD6
6
1
1
6
PD5
PD5
PD5
PD5
PD5
PD5
DIR
5
PE
5
1
4
IRQEN
- 82 -
SLCT
PD4
PD4
PD4
PD4
PD4
PD4
IRQ
3
4
2
ERROR
1
SLIN
SLIN
PD3
PD3
PD3
PD3
PD3
PD3
3
W83977F/ W83977AF
0
Publication Release Date: January 1997
PD0
PD1
PD2
PD3
PD4
PD5
PD6
PD7
INIT
INIT
PD2
PD2
PD2
PD2
PD2
PD2
2
1
AUTOFD
AUTOFD
PD1
PD1
PD1
PD1
PD1
PD1
PRELIMINARY
1
1
Revision 0.50
STROBE
STROBE
TMOUT
PD0
PD0
PD0
PD0
PD0
PD0
0