Citizen Systems CBM-290 - Manual (Page 26)

CITIZEN 26
6.3 Electrical characteristics
(1) Input Signal Level
All the input signals are at TTL level.
"HIGH" level
: 0.7Vcc MIN
"LOW" level : 0.3Vcc MAX
(2) Output Signal Level
All the input signals are at TTL level.
"HIGH" level
: Vcc – 0.1V MIN
"LOW" level : 0.1V MAX
(3) I/O Conditions
Input signal of STB and RESET are pulled up by 3.3K Ohm. Others are pulled up by 50K Ohm.
<Printer side> <Host side>
All the output signals are pulled up by 50K Ohm.