As you know, I am (or at least, used to be) somewhat of an RT-200
aficionado myself (back in the day - late 1980's - some of us used to envy biomeds who had access to this fine piece of test equipment). But perhaps it may help if you gave us an idea about what you are trying to achieve here.
The RS-232 interface was an optional extra. Where installed, the connector to the outside world would occupy slot J-1 as shown at top left of the second image at post #76167 (see also the image posted below).
Slot J-2 was for the IEEE-488 interface connector. The General Purpose Interface Bus (GPIB - originally from Hewlett-Packard) is apparently still often found on test equipment of the "bench" type. I have never seen an RT-200 with GPIB myself. I haven't been able to find an image of an RT-200 with GPIB on line, either.
It would be nice if you could bring these interfaces back to life; as well as - who knows - adding new ones (
eg, USB). Apparently, GPIB to USB adaptors are available these days. As well as:-
clue.
One of the things I liked about the RT-200 are the opportunities it appeared to offer for expansion. As you know, there are a number of empty connectors on the main board. In this regard I am reminded of 8-bit computers from the same era (especially the BBC Model B and (or) Master). Who knows what use they could be put to!
The design of the RT-200 suggests a "stack", and I have often wondered if Timeter planned more modules. Its predecessor, the RT-100, included a voltmeter and electrical safety tester, and I imagine that the RT-200 could have offered those within another module (I had, at one time, toyed with the idea of adding my own). It would have been nice also to have a module that could handle fluids (for testing infusion pumps
etc.). The extra bus connector (see the ribbon cable at top left of the bottom image - the Flow module - at #76169) seems to suggest such possibilities.
As we have found, one of the problems with keeping the RT-200 going (as well as, perhaps, enhancing its capabilities) is a lack of detailed technical information. Connector pin-outs, chip numbers
etc. As you have already indicated, this equipment stems from a time when chips were often rendered anonymous! I'm guessing, too, that some of those chips (MCUs) may now be hard to find, and their function may therefore need to be "re-created" in some imaginative way. No doubt you can look forward to many hours of fun!
Lastly, I have yet to hound down any information regarding the DIP switches (S1-S8) on the main board. The manual simply mentions "Programming Switches" (S1-S6 appear to be ON, S7-S8 OFF).
Knowing of your interest, this morning I got in touch with the guy to whom I donated my own RT-200 six years ago. It was a nice clean example (but no J-1, or J-2 interfaces, alas). I was wondering if it was still unused, so maybe I could retrieve it, and then possibly answer some of your questions. Apparently he uses it in some sort of project where he has a need to measure water flow (hopefully, he uses some kind of liquid-to-air adaptor). At least, then, it has gone to a good home!
