Custom Engineering PLUS II - Parallel TTL Interface Signals

For parallel TTL interface printer the communication signals are: 8 bit DATA BUS, STROBE (indicate the data
validity) and BUSY (indicate that the printer is ready to receive data).
Transmission format
VALID DATA
VALID DATA
D0...D7
STROBE
BUSY
Flow diagram
ERROR
NO
NO
NO
SI
NO
SI
SI
OUT DATA
OUT STROBE=0
OUT STROBE=1
START
RETURN
TIMEOUT
> 1 sec.
TIMEOUT
> 4 sec.
BUSY=1
BUSY=0
(Fig.2.7)
2. INTERFACES
2-8 PLUS II User Manual