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quieterthanbombs
December 28th, 2010, 05:27 PM
Hi Guys,

I've come across a VT100 keyboard that my dad had from about '81, and I'm trying to hook it up to a more modern computer. I took it apart and it looks like it's in pretty good shape.
5015

So as you know, it's got one of these TRS plugs. I fortunately have a jack to use with it (pictured):
5014

Unfortunately, I'm really not sure how to connect it to my computer. I took it apart and have found this plug (the white, red, and black lead to the terminal)
5013

I thought initially, given my experience with USB, that the keyboard cable uses a 3-pin RS232 connection, which would be very simple to just wire to a normal DB9 connector. Unfortunately, after reading the technical reference on bitsaver (http://www.bitsavers.org/pdf/dec/terminal/vt100/EK-VT100-TM-003_VT100_Technical_Manual_Jul82.pdf), it looks like the cable carries TxD and RxD on one line, and clock and ground on the other two.

Does anyone else have a handle on this keyboard's pinout? Are my assumptions correct? And if they are, how do I wire up an adapter from this cable to something useful like RS232 or USB without the terminal itself?

tl;dr: I want to connect this keyboard to a modern computer but don't understand the pinout.

I really look forward to being able to use this keyboard again.
Thanks in advance,
Sam

Lou - N2MIY
December 28th, 2010, 06:26 PM
Sam,

There is no simple way to cable this keyboard up to an IBM PC. It would be a good microcontroller project to build an interface to take what this keyboard puts out and digitally and electrically make it compatible with a PC keyboard connection. If you have the VT100 technical manual, you will see exactly what it puts out.

If you really want to use this keyboard again, you should connect it to the VT100 terminal it came from.

Alternatively, I have seen VT100 basic video boards (the main board) for sale on ebay. Add a power supply (with appropriate voltages) and you get RS232 output when you type on the keyboard. (That's what termainals do!)

Flat screen TVs are getting so cheap now, I have also thought about making a slim VT100 using the VT100 basic video board and flat screen TV. When mounted inside a real VT100, the basic video board gets cabled to a separate analog video section that drives a CRT, however, the basic video board also has on it a BNC baseband black and white (RS170) video output that could drive an external monitor! I have repaired many real VT100s though and never seem to have just a spare basic video board floating around.

Lou

RickNel
December 29th, 2010, 05:25 PM
I agree, the best use would be to connect to a VT100, if it could be found. The keyboard puts out many codes that are unique to the VT100 or related DEC terminals - eg the top row of setup options and the cursor control keys. It is designed to be integrated with the VT100. I believe there are always people out there with VT100 terminals who would love to acquire a keyboard in good condition...

A microcontroller project is possible, but it would be like scratching your right ear with your left hand.

Rick

iprefermuffins
January 6th, 2011, 11:50 AM
Hey, I'm one of those people who would love to acquire a keyboard. Or more precisely, I need replacements for 3 missing keycaps on the keyboard I already have, on a VT102 that Lou helped me fix last year. I have some more plans for it, but it's kind of on a back burner right now. So on the off chance that you're willing to part with (or scavenge keys from) your keyboard...

Kevin

mrphantuan
January 21st, 2011, 12:06 AM
I agree, the best use would be to connect to a VT100, if it could be found. The keyboard puts out many codes that are unique to the VT100 or related DEC terminals - eg the top row of setup options and the cursor control keys. It is designed to be integrated with the VT100. I believe there are always people out there with VT100 terminals who would love to acquire a keyboard in good condition...

A microcontroller project is possible, but it would be like scratching your right ear with your left hand.
a
Rick
I agree , me too