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APPENDIX
Appendix B: Parallel Interface
B-1. Interface Specifications
The operating specifications of the parallel interface are as follows.
(1) Data transfer rate : 1000 to 6000 characters per second
(2) Synchronization : Via externally supplied STROBE pulses
(3) Handshaking : ACK and BUSY signals
(4) Logic level : Compatible with TTL level
B-2. Interface Timing
Fig. B-1 Interface timing diagram
Signal Name Circuit Example
DATA 1-DATA 8
(To Printer)
STROBE
(To Printer)
BUSY, ACK
(From Printer)
Fig. B-2 Typical interface circuit
ACK
Approx.9 µs
Data
STROBE
BUSY
TTT
T:more than 0.5 µs
74HC Compatible
4.7KΩ
100Ω
470pF
74HC Compatible
1KΩ
1.8KΩ
74LS Compatible
INPUTOUTPUT