Acrosser AR-B1320 - Manual (Page 16)

A A R R - - B B 1 1 3 3 2 2 0 0 U U s s e e r r ’ ’ s s G G u u i i d d e e
(3) Data Swapper
The system microprocessor can read the contents of the printer's Data Latch through the
Data Swapper by reading the Data Swapper address.
(4) Printer Status Buffer
The system microprocessor can read the printer status by reading the address of the Printer
Status Buffer. The bit definitions are described as follows:
X X X
1 2 3 4 5 6 7 0
-ERROR
SLCT
PE
-ACK
-BUSY
Bit 7: This signal may become active during data entry, when the printer is off-line during
printing, 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. A 0 means the printer
has received the character and is ready to accept another. Normally, this signal will be
active for approximately 5 microseconds before BUSY stops.
Bit 5: A 1 means the printer has detected the end of paper.
Bit 4: A 1 means the printer is selected.
Bit 3: A 0 means the printer has encountered an error condition.
Bit 0-2: No meaning.
(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 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 writing only.
Bit 4: A 1 in this position allows an interrupt to occur when ACK changes from low state to
high state.
Bit 3: A 1 in this bit position selects the printer.
Bit 2: A 0 starts the printer (50μsecond pulse, minimum).
Bit 1: A 1 causes the printer to line-feed after a line is printed.
Bit 0: A 0.5μsecond minimum high active pulse clocks data into the printer. Valid data must
be present for a minimum of 0.5μseconds before and after the strobe pulse.
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