SB-10 USER'S MANUAL

APPENDIX
INTERFACES
This appendix contains the technical information necessary to
connect the printer to your computer using each of the three possible
interfaces: parallel, serial, and IEEE-488.
• THE PARALLEL INTERFACE
Your printer uses a Centronics-compatible parallel interface capable
of transferring from 1,000 to 6,000 characters per second.
Externally supplied STROBE pulses accomplish synchronization of
data transmission. ACK and BUSY signals govern the
“handshaking” between your computer and the printer. Parallel
interface uses a TTL-compatible logic level.
Functions of the connector signals
Pin 1 carries the STROBE pulse signal from the computer to the
printer (see Figure H-l). When the computer has data ready for the
printer it sets this signal to low value for at least 0.5 microseconds.
When the printer sees this pulse on the STROBE pin, it reads the data
supplied by the computer on pins 2-9. Each of these lines carries
one bit of information. A logical “1” is represented by a high signal
level, and a logical “0” is represented by a low signal level. The
computer must maintain these signals for at least 0.5 microseconds
before-and 0.5 microseconds after-the STROBE pulse.
When the printer has successfully received the byte of data from
the computer, it sets the Am signal (pin 10) low for approximately
9 microseconds. A high BUSY signal (pin 11) reportswhen the printer
is unable to receive data. This signal will be high during data transfer
when the printer is off-line, or when an error condition exists. See
the circuit example of these signals in Figure H-2.