Heathkit H9 Manual page 26

Parallel Handshake Timing
Pictorial 2-18 shows the timing waveforms of the
handshake signals associated with the parallel I/O
port.
D AV0
TERM I NAL
RD AVO
T XTT RN AL
DAVI
EXTERN AL
RD AVI
I ERM INAL
S A YS '' A LL DON T . ' '
LOW LTVEL SAYS "DAT A R EA D Y FOR EX I E R N A L D E VI C E .
Handshake Timing
LOW LEVFL SA Y S '' I'V E GOT I I. "
LOW LFVEL SAYS H A V E D A IA FO R Y OU . ''
_ rl Zl.susk_P ULS E S AY S " I'V E TAK EN THE DATA. "
- t--' ---l
PICTORIAL 2.IB
Serial I/O Connections
The following serial I/O connector chart describes the
signals on each pin of the serial I/O connector on the
rear panel.
PIN #
SERIAL PORT NOMENCLATURE
TTY (ACTIVE
AND PASSIVEI
EIA RS-232C
TTL
7
Serial Out [+) Serial Out
2
Serial Out (-)
Serial Out
3 Serial In (+)
Serial In
4
Serial In [-) Serial In
5
Reader Start (+)
6
Reader Start (-)
Baud Rate Out Baud Rate Out Baud Rate Out
B
9
Ground Ground
Ground
II Tr r vr u s T c o H rG H w tT H r N r 4 us
OF T R A IL IN G E D G E O F P UL SE
RDAV-o R ESEI S D ATS