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Thread: Morse-Baudot

  1. #1
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    Default Morse-Baudot

    Does anyone else have one of these Morse-Baudot S-100 boards by Curtis Electro? It looks like basically a fancy UART with onboard ROMs to presumably handle ASCII to Morse conversion. I'm interested to learn how it operates, would it take an audio input from a HAM radio via the RCA jack and decode the dots and dashes? There's also an empty DIP socket in the upper left, perhaps a connection to some other peripheral. I don't know HAM radio, so wondering if someone else can take a more educated guess.

    The big chip on the board is an AY-5-1013a

    IMG_2511.jpg

  2. #2
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    Not sure at this stage in computing any one was good at converting received morse to dots and dashes on screen. The trouble is that certaining when this card was built a lot of morse was hand sent so there is a lot of variability in for example the lengths of the dots and dashs, which computer programs find hard to work with. Do I have that right? There are 8k of code on there? I think you need a manual
    Dave
    G4UGM

    Looking for Analog Computers, Drum Plotters, and Graphics Terminals

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    FWIW, Jack Curtis passed away last year at age 87. He was known mostly for his keyer devices.

  4. #4

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    Looking at the back of the board, the empty socket may have had an op-amp. It looks to have unusual power pins. I suspect they are +/- 15V.
    Dwight

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    Using an IMSAI with the Cromemco 8K bytesaver (I knew it would come in handy some day) I was able to dump the contents of the ROMs into a HEX file capture on my laptop terminal and from there convert it to a 7K binary. The address switches on the Morse-Baudot board were set to A0, presumably that's where the ROM code would start. It should be Intel 8080 code.

    It is a curious question how this thing would work if decoding human generated Morse code, perhaps it was only meant to receive from another Morse-Baudot board, that way one could expect a fixed rate of transmission.ROMs.txt

  6. #6
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    There were (and are) programs that decode hand sent morse. Basically you use heuristics to work out if its a dot, dash and if the space is an inter-element space. This paper (behind a pay wall) dates from 1959 so folks have been looking at it for a while...

    https://ieeexplore.ieee.org/document/1057478

    have a google...
    Dave
    G4UGM

    Looking for Analog Computers, Drum Plotters, and Graphics Terminals

  7. #7

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    Quote Originally Posted by new_castle_j View Post
    I was able to dump the contents of the ROMs into a HEX file capture on my laptop terminal and from there convert it to a 7K binary. ROMs.txt
    Just a question about the file as the whole Rom thing worries me in terms of data retention and I'm fairly new to programming and using Roms. In that file, towards the end, there are some broad zones where a number of the byte values have gone to (or were originally FF). Is that the sort of appearance one gets in a Rom file when there is Rom rot ? Or would it look different ? I noticed that there were no light occlusive covers over the Rom windows, so they might have been more at risk of it ?

  8. #8
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    Sometimes (and you find this in a lot of early code), routines need to be at fixed locations, so the intervening unused spaces simply aren't programmed.

  9. #9

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    I believe 2708s erase to 0FF so 0 is ok.
    Dwight

  10. #10

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    Quote Originally Posted by Chuck(G) View Post
    Sometimes (and you find this in a lot of early code), routines need to be at fixed locations, so the intervening unused spaces simply aren't programmed.
    So you are saying that the sort of appearance seen there in that file with the zones of FF's you would judge as probably original programming ?

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