Specifications

AR-B1564 User¡¦s Guide
2-8
(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:
Figure 2-2 Printer Status Buffer
NOTE: X presents not used.
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 can not
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 receiving a BUSY message stops.
Bit 5: A 1 means the printer has detected the end of the paper.
Bit 4: A 1 means the printer is selected.
Bit 3: A 0 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:
Figure 2-3 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: 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 (50 microseconds pulse, minimum).
Bit 1: A 1 causes the printer to line-feed after a line is printed.
Bit 0: A 0.5 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.