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Zenith Data Systems - Z-39 Terminal (1985)
I got this terminal the same time as i got the icl terminal (i saved both of them from being thrown away, about 11 years ago), on the back of the terminal is two 25pin ports (one male and one female) plus one Rj11 socket for the keyboard, i think the two 25pin ports are serial ports (one for a printer and one for data), it powers on and shows a blinking cursor, an on-line timer and a keyboard error, but thats because i don't have a keyboard for it, so i can't properly test it out, i've tried to find out what the pins do and from what i can see, pin 1 = +12v, pin 2 = +5v, pin 3 = ??, pin 4 = ??, pin 5 = 0v, pin 6 = 0v, i tried connecting the keyboard from the icl terminal, the icl keyboard pins look to be, pin 1 = +12v, pin 2 = 0v, pin 3 = +5v (may also carry data), pin 4 = 0v, but when i connect up the icl keyboard, i just get some kind of data come up on the screen (still showing the keyboard error) but it just looks like garbage, i even tried connecting up an old pc keyboard, but again i only get garbage but this time it looks like binary, it might need some kind of serial/TTL keyboard or something like that, if anyone can help me out with this, i would be really grateful.

***** Update *****
after tracing were the two data pins goto for the keyboard, i found that pin3 go's to pin4 (output) of a HEX inverter (SN74LS04), then on to pin1 of the CPU (Philips MAB 8031AH 12P), pin4 from the keyboard go's to pin13 (input) of the HEX inverter, then on to pin2 of the CPU, i'm thinking that maybe pin3 (output) might be for some kind of clock signal for the keyboard and pin4 (input) must be the key data from the keyboard or maybe it might just be a standard serial interface.
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Page last Updated: Tue the 4th of Feb 2020