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Thread: Doesn't anyone else want to BBS with their PET?

  1. #51
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    Quote Originally Posted by daver2 View Post
    OK.

    I haven't been able to find any documentation (yet) for this device - but only been looking for 10 minutes...

    First off - the two UARTS (TR1602-B) are made by Western Digital and the data sheet can be found here http://ae6pm.com/Semidata_sheets/TR1602B.pdf.

    From the data sheet I can see pin 35 is the Parity Inhibit; pin 36 selects the number of stop bits; pins 37 and 38 select the number of data bits; pin 39 enables even parity and pins 17 and 40 are the RX and TX clocks respectively.

    By inspection (or the use of a multimeter set to Ohms) it should be now possible to work out the serial port configuration links by tracing the wiring from pins 35-39 of each UART to the configuration blocks.

    I see there is a crystal on the board. The crystal will be connected to an oscillator circuit and this (in turn) will be connected to 1 or 2 BAUD RATE GENERATOR ICs. These will be connected to the jumper blocks for the BAUD rate selection for each UART (and hence to pins 17 and 40 of the UARTS). Again, by identifying the data sheets and tracing out the circuitry it should be possible to identify what BAUD RATE is associated with each link.

    The IEEE 488 address we should be able to work out by trial and error...

    You will need a Commodore PET to IEEE 488 cable and a terminator.

    Can you get some further close-up pictures of each device on the board for me? I should then be able to identify the BAUD RATE GENERATOR(s) and RS232 buffers for you. Tracing the transmit and receive data to/from the UART devices will be the best way of identifying the RS232 buffers.

    It's getting late in the UK so I will pick this up again tomorrow.

    Regards,

    Dave
    Dave I will get you some photos soon, but I am tired as well from working outside today.
    One thing you mentioned. I have the ieee 488 cables, but I dont have a terminator. I never heard of that with IEEE 4888. My pet communicated with my SFD-1001 without a terminator, can you explain how its used?

  2. #52
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    I don't recall the schematics, but likely your PET and SFD did not work without termination. They likely have it built in.

    HPIB might be able to get by without bus termination, in a pinch.

  3. #53
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    So its like Scsi? IS there an actual physical terminator I need to get or is this configured per device? Im curious.,

  4. #54
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    Yes, but it's not just SCSI. Any data bus technically requires termination. Sometimes you can get by without it, especially at low speeds.

    Thinking about how the connectors work for HPIB, there probably isn't any termination. So the speed must just be low enough that we all get by without it. But again I'd have to see schematics or maybe a specification for the bus to know for certain.

  5. #55
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    Ignore the bit about termination - I was working too late last night obviously!

    The IEE 488 bus does not require a terminator (it is operating at relatively slow speeds).

    Unable to find any documentation myself today on your TNW488/232 - so we will have to reverse engineer the functionality.

    No problem regarding the photographs - when you are ready. I have plenty to do at home myself...

    Dave

  6. #56
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    Quote Originally Posted by daver2 View Post
    Ignore the bit about termination - I was working too late last night obviously!

    The IEE 488 bus does not require a terminator (it is operating at relatively slow speeds).

    Unable to find any documentation myself today on your TNW488/232 - so we will have to reverse engineer the functionality.

    No problem regarding the photographs - when you are ready. I have plenty to do at home myself...

    Dave
    Dave I added some close up photos of the board and zoned them as to help (and hopefully not confuse) http://s613.photobucket.com/user/Ver...s-232%20device
    if any images are blurry or you need a better photo just let me know.

  7. #57
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    Excellent.

    I will have a look tonight.

    Dave

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