W83877 Winbond Electronics Corp America, W83877 Datasheet - Page 61

• Manufacturer Part Number: W83877
• Description: Winbond I/O
• Manufacturer: Winbond Electronics Corp America

5.3.4 Device Control Register (DCR)
The bit definitions are as follows:
Bit 6, 7: These two bits are logic one during a read and cannot be written.
Bit 5: This bit has no effect and the direction is always out if mode = 000 or mode = 010. Direction is
Bit 4: Interrupt request enable. When this bit is set to a high level, it may be used to enable interrupt
Bit 3: This bit is inverted and output to the SLIN output.
Bit 2: This bit is output to the INIT output.
Bit 1: This bit is inverted and output to the AFD output.
Bit 0: This bit is inverted and output to the STB output.
5.3.5 cFifo (Parallel Port Data FIFO) Mode = 010
This mode is defined only for the forward direction. The standard parallel port protocol is used by a
hardware handshake to the peripheral to transmit bytes written or DMAed from the system to this
FIFO. Transfers to the FIFO are byte aligned.
5.3.6 ecpDFifo (ECP Data FIFO) Mode = 011
When the direction bit is 0, bytes written or DMAed from the system to this FIFO are transmitted by a
hardware handshake to the peripheral using the ECP parallel port protocol. Transfers to the FIFO are
byte aligned.
requests from the parallel port to the CPU due to a low to high transition on the ACK input.
valid in all other modes.
0
1
0
1
the parallel port is in output mode.
the parallel port is in input mode.
The printer is not selected.
The printer is selected.
7
1
6
1
5
4
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3
2
1
0
Publication Release Date: January 1996
strobe
autofd
nInit
SelectIn
ackIntEn
Direction
W83877F
Revision A2