ST78C34 Exar Corporation, ST78C34 Datasheet - Page 9

• Manufacturer Part Number: ST78C34
• Description: General Purpose Parallel Printer Port With 83 Byte Fifo
• Manufacturer: Exar Corporation

AFR BIT-6:
INT output polarity.
0= Normal. INT output follows the -ACK input
1= Inverted INT output
AFR BIT-7:
FIFO enable / disable function.
0= FIFO is disabled( default mode).
1= FIFO is enabled. Internal 83 byte of FIFO is
enabled.
FIFO BYTE COUNT REGISTER (FBCR)
State and content of the printer FIFO can be moni-
tored by reading this register.
FCBR BIT 0-6:
FIFO byte count. Number of characters left in FIFO.
FCRB bit-0 is the LSB bit of the counter and FCRB bit-
6 is the MSB bit of the counter.
FBCR BIT-7:
FIFO state.
0= FIFO is enabled
1= FIFO is disabled
Bit-5 Bit-4 INT output
Rev. 3.00
0
0
1
1
0
1
0
1
Normal mode
FIFO empty
FIFO full
FIFO empty
bit-0
STR
1
1
0
1
STR
bit-6
-ACK
FIFO empty
FIFO full
FIFO empty
6-11
ST78C34 EXTERNAL RESET CONDITION
SIGNALS
PD0-PD7
-STROBE
-AUTOFDXT
INIT
-SLCTIN
RESET STATE
Unknown, output mode
High
High
Low
High
ST78C34