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Thread: Help needed: identifying which computer was this program written for

  1. #1

    Question Help needed: identifying which computer was this program written for

    Hello everyone.

    I found an old tape with two homemade programs written on it, one on each side. I would be highly interested in backing up these programs as ROM files. However, I do not know what computer they were programed for.

    These are the links to the .wav files:

    https://ftp.ea4rct.org/radioclub/upl.../factorial.wav

    https://ftp.ea4rct.org/radioclub/upl.../polarCart.wav

    Sadly, I have no enought experience for finding this information, and there does not seem to be any straightforward solution to this issue but finding someone that recognises the sound of the preamble/program. I post this here with the hope of finding someone that can tell either which computer these recordings correspond to or, at list, start ruling out candidates.

    Thank you very much in advance!

  2. #2
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    Probably need to decode to binary....
    Dave
    G4UGM

    Looking for Analog Computers, Drum Plotters, and Graphics Terminals

  3. #3

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    Honestly, you should convert these in to binary and start throwing disassemblers at them. You should try a 6502 disassembler and a Z80 disassembler.

    Both of those will be pretty enlightening pretty quick.

    Even if you don't have great familiarity with assembly language, odds are high that one disassembly will look like utter nonsense, and the other one more signal, than noise.

    Once you've done that, I bet if you pasted a page of the disassembly, notably anything that looks like it makes calls "outside" of the program (for 6502 that would likely be JSRs to higher addresses, on the Z80/8080 it's probably interrupts). Also, on the 6502 any Zero Page addresses will tell tale it quite quickly.

    And, of course, I say 6502 and Z80 because that's 90+% of what anything was written for in the day. The odds of it being a 6800 or TMS9900 or anything else is REALLY low.

    So, give is a couple of stabs with some disassemblers and post your results.

  4. #4

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    Wouldn't you need to know for which computer these are for in order to convert them to binary? But if he knew that, this thread wouldn't exist.

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    Quote Originally Posted by Timo W. View Post
    Wouldn't you need to know for which computer these are for in order to convert them to binary? But if he knew that, this thread wouldn't exist.
    Not necessarily. It should be possible to figure out the frequency of the leader and the frequency of the signal shifts and whether or not stop bits are used from the wave form. That would narrow the list of possible systems to just a few.

    I suspect it would be faster to write a new version of these programs than to extract from the cassettes. A factorial program was a sample for the Sol 20 and Wang 2200. Presumably, the other would be for converting Polar Cartesian coordinates which I think was an assignment in Intro to Programming 40+ years ago.

  6. #6

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    Thank you very much for the info!

    Efectively, this tape corresponds to some homework of an engineering student almost 40 years ago!

    I can try converting them to binary. Is there any recommended software for this purpose?

    Thanks!

  7. #7

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    Thank you for your response!

    Would you recommend any software for any of both (conversion to binary/disassembly) purposes?

  8. #8
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    I think you are out of bandwidth! I would try feeding it into MMTTY. This will show you the mark/space frequencies and decode it if its 300 baud or less...
    Dave
    G4UGM

    Looking for Analog Computers, Drum Plotters, and Graphics Terminals

  9. #9

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    Quote Originally Posted by g4ugm View Post
    I think you are out of bandwidth! I would try feeding it into MMTTY. This will show you the mark/space frequencies and decode it if its 300 baud or less...
    Dear Dave G4UGM. What do you mean by out of bandwidth? Does this only refer to MMTTY?

  10. #10
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    Quote Originally Posted by pkmpad View Post
    Dear Dave G4UGM. What do you mean by out of bandwidth? Does this only refer to MMTTY?
    I can't download the files you linked to. Is the site they are on bandwidth limited?
    Dave
    G4UGM

    Looking for Analog Computers, Drum Plotters, and Graphics Terminals

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