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Thread: Model 1 expansion interface and floppy drive not working

  1. #21

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    I received the interconnect cable today.

    here's what happens: floppy drive on connector nearest EI. power on EI & FD. FD spins, LED on momentarily. power on CPU, garbage screen similar to Mav's in his great video 'TRS-80 Model 1 vintage computer set up and boot up - part 1'. Press reset button, garbage screen, FD spins and LED on then it stops. Still garbage on screen.

    However, the only floppies I have are Model 3 floppies that came with my Model 4. a couple of copied games with LDOS and a few factory programs such as accounts payable (all labeled Model III). I know these disks work on the model 4. So far I've only tried one EI and one FD. I have more FDs, one of which spins up. I also have a color computer FD.

    potential answers to this? compatibility between model 1 and model 3/4 FDs? Or DOS compatibility with model 1? or I still have a hardware (drive) issue. I thought the 3 and 4 were mostly backward compatible, but it may not work the other way?

    I feel like this is some level of progress, but I'm too tired to work on it any more tonight.

    thanks for everyones' help.
    Last edited by Dokken; October 11th, 2018 at 03:49 PM.

  2. #22
    Join Date
    Jun 2015
    Location
    Sioux Falls SD
    Posts
    177

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    You can't use Model III disks in a Model I. Contact Ira at trs-80.com. He has a standing offer to make boot floppies for folks in need.

  3. #23

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    Quote Originally Posted by lafos View Post
    You can't use Model III disks in a Model I. Contact Ira at trs-80.com. He has a standing offer to make boot floppies for folks in need.
    i sent ira the email. I was sure I had a model 1 disk and i'll keep looking.

  4. #24
    Join Date
    May 2013
    Location
    Williamstown Victoria Australia
    Posts
    399

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    @Dokken
    What happens after you have powered every thing up.
    Could you hold down the BREAK Key and while holding it down Press the Reset Button Please
    and tell us what happened on the screen ???
    Thanks Ray
    If it ain't Broke then PLEASE DONT fix it.
    Procrastinators Unite.
    I keep telling you I am Not Pedantic.

  5. #25

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    Quote Originally Posted by Audronic View Post
    @Dokken
    What happens after you have powered every thing up.
    Could you hold down the BREAK Key and while holding it down Press the Reset Button Please
    and tell us what happened on the screen ???
    Thanks Ray
    just tried it. with garbage screen, i held BREAK and hit the reset button. i get the MEMORY SIZE? prompt but enter does not seem to do anything. what would you expect to see?

    thanks

  6. #26
    Join Date
    May 2013
    Location
    Williamstown Victoria Australia
    Posts
    399

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    From Memory
    I think Press ENTER twice and you should get " READY" if that works type "?MEM"

    Try that Ray
    If it ain't Broke then PLEASE DONT fix it.
    Procrastinators Unite.
    I keep telling you I am Not Pedantic.

  7. #27

    Default

    Quote Originally Posted by Audronic View Post
    From Memory
    I think Press ENTER twice and you should get " READY" if that works type "?MEM"

    Try that Ray
    ?mem with no EI attached = 15562
    ?mem WITH EI attached = 48340

    good sign I guess? that indicates that the CPU recognizes the ram in the EI? Now i guess i'm down to the floppy drives working (once i get my dos disks).

    thanks for that tip.

  8. #28
    Join Date
    May 2013
    Location
    Williamstown Victoria Australia
    Posts
    399

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    Ok That good

    I think that the Expansion is working OK as when the Floppy drives are active for about 2 seconds after a reset that seems about right.
    Get a copy of an OS in SINGLE DENSITY to start with. LDOS or NEWDOS.
    Good luck Ray
    If it ain't Broke then PLEASE DONT fix it.
    Procrastinators Unite.
    I keep telling you I am Not Pedantic.

  9. #29

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    thanks.

    i learned that the break key switch is broken on the CPU i am testing with. the square insert that slides inside the housing is cracked on two corners and sticks every time. made testing difficult. i pulled out another model 1 to test this.

    i have a spare board/keyboard CPU with the key switches on it, so i'll probably replace the switch on my working unit.

  10. #30

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    Ira's package of various M1/M3 dos and utility disks arrived today via priority mail. such a nice service he is providing. i immediately sent him a donation.

    I have not had time to do much more than a quick check, but i'm not getting a DOS screen. power on sequence as discussed, insert floppy, press reset. garbage screen comes up and stays, drive spins then stops. i tried 3 drives with the same result. but i have not done much else. i'll get back into it this weekend.

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