Owner's manual

AR-B1550 User’s Guide
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Bit 7: This signal may become active during data entry, when the printer is off-line during p
rinting, or when the
print head is changing position or in an error state. When Bit 7 is active, the printer is busy and cannot
accept data.
Bit 6: This bit represents the current state of the printer’s ACK signal. A0 means the printer has received th
e
character and is ready to accept another. Normally, this signal will
be active for approximately 5
microseconds before receiving a BUSY message stops.
Bit 5: A1 means the printer has detected the end of the paper.
Bit 4: A1 means the printer is selected.
Bit 3: A0 means the printer has encountered an error condition.
(5) Printer Control Latch & Printer Control Swapper
The system microprocessor can read the contents of the printer control latch by reading the address of printer
control swapper. Bit definitions are as follows:
X X
1 2 3 4 5 6 7 0
STROBE
AUTO FD XT
INIT
SLDC IN
IRQ ENABLE
DIR(write only)
Bit’s Definition
NOTE: X presents not used.
Bit 5:
Direction control bit. When logic 1, the output buffers in the parallel port are disabled allowing data driven
from external sources to be read; when logic 0, they work as a printer port. This bit is write only.
Bit 4: A1 in this position allows an interrupt to occur when ACK changes from low state to high state.
Bit 3: A1 in this bit position selects the printer.
Bit 2: A0 starts the printer (50 microseconds pulse, minimum).
Bit 1: A1 causes the printer to line-feed after a line is printed.
Bit 0:
A0.5 microsecond minimum highly active pulse clocks data into the printer. Valid data must be present for
a minimum of 0.5 microseconds before and after the strobe pulse.