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For anything memory-mapped, one shall look at A14 & A15. A14 should be tested as high and A15 should determine if the target is ROM or RAM. Banks should be higher than 7 though.

Having designed hardware for the Datamaster recently, I am very interested in your findings. Do you think an ISA diagnostics card could be easily adapted to the Datamaster bus? The more the tools we have at our disposal, the better.

@NeXT I am curious about your unit. I see through some pictures that you have the later dark-brown one, but I would like to know how is your RAM structured: do you have a single 64k board or two 32k boards? If you need anything feel free to ask, I will share the few things I know. By the way...

You have been entrusted with a very special system. Taking care of it may be enough. The duty is yours to handle it down to the next generation when the time comes. We all have our roles in the big scheme of things. Ours is to preserve the history of our profession before it is reduced to...

Many things need to be double-checked in this system. Myths need to go down and replaced with facts. In other words they did even kept the Datamaster bus intact when designing the IBM PC, so that's great! I have just discovered that in the S/36 the async boards are the ones from the PC-XT...

Not that I know - with the exception of the emulator. Just having a proper place to talk about them brought the discussion itself.

My model is one of the older 5363, no II or III. I don't know if my system uses the ISA bus. How could I determine it? I'll take a look into the docs available at bitsavers. EDIT: The system has not been expanded previously. About microcode, I lack the floppies - would it be the same across...

I love how different Soviet computers look like. You did a good job restoring it.

Hello, I am considering an upgrade on my System/36 5363 and one of the facets I find it somewhat lacky is in communications. For this reason I would like to know if there was some sort of communications card available and what protocols would they use (modem? token-ring?). Maybe I focus on a...

The issue with the articles in the pre-PC systems is mostly solved now. Hadn't it been an IBM category, everything would have gone to "others", but at it existed threads were going to early PCs; as Datamasters are labelled as System/23 and its basic is compatible with the S/34 other people...

As far as I know, IBM made the parity check at least from the System/3, when memories were ferromagnetic. If anything, it means they built their small systems having their experience with minicomputers (midranges) in mind. It would be interesting to repeat that benchmark. Only if we knew what...

Thank you very much! This will be very helpful. :)

Hello, I recently purchased an Epson PC-J3, which has the same "Mars Board" than the Epson Equity I. Apparently the system seems to work but as the original video cable is missing, I cannot be completely sure. Its monitor is the original one, as it is the one that appears in the manuals and in...

Hello, I enclosed the board, so it has keyboard again! Unfortunately the program didn't execute successfully. What I can say for sure is: Really the operator cannot distinguish between "l" and "1". The graphic characters are generated by a combination of the 8275 special chars plus...

Preparing for a 3-week period where I won't be able to experiment with it, my 5322 has been enclosed again. Still, design work on prototypes continues and I expect before the end of the month to make another boards order. For in case anybody is wondering, I will open my designs in time; however...

@Al Kossow No, there was people interested, the problem is that with the older structure the information fell into four to five different categories. If they are minoritary beacuse there aren't many units this breaks completely the sense of a single group. I also think that something that...

I made a small list of threads to be moved into the non-PC category: https://forum.vcfed.org/index.php?threads/ibm-system-23-datamaster-display-and-character-generation.1247762/ https://forum.vcfed.org/index.php?threads/searching-for-ibm-s-23-datamaster-users.1241962...

Hello, As the title implies, I am studying the components in the Type F keyboard. Generally there are not many components other than an 4048, a SLT and passives. By examining the PC-XT schematics it seems it is some kind of analog amplifier (a sense amplifier?) but I am not very familiarized...

My three four tips for long-term survival and service: First, I try to avoid old components and use ones currently in production. Second, I also use to limit the models of certain components - for example memories - so that's easier to stockpile them si at long term failures can be easier to...

Hello, The prototypes arrived a few days ago. The ram boards are defective and a revised batch should be ordered. With other prototypes I had mixed results - but it has been my fault entirely. In any case, I have a simple rom patch for the memories 02h and 09h which works more or less...