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Thread: Model 4GA Woes: Catastropic Failure of the Smoke Test, Visible Victim U81

  1. #11

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    Well Ian's videos only seem to deal with the ALPS keyboard so I guess I will check to see if Jay has any M4 ALPS Keyboards around and then check to see if he has a 4D cable. I have had very good luck with the Mitsubishi 4851 drives and I want to try the 4853 (DSDD). So this project continues, another M4851, another FreHD (my M3 has one), upgrade to 128K RAM and then possibly the 3.5s as external drives. I know Ian can make the cables for both the internal and external drives. Anyway will keep the status updated here as I wobble along.

    Cheers
    Ross
    Collection: TRS-80 Model 3 w/autoboot FreHD, TRS-80 Model 4 (X2), TI-99/4a (X2) w/PEB, Timex Sinclair ZX-81 w 16K module, Raspberry PI (X5), 1u eServer running Linux, Intel Brick Computer running Linux, Dell Optiplex 160 (X2) 1 running Win7, 1 running Linux, Dell Optiplex 755 running Win10, Mini MAC (Apple)(X2), a hacked together AMD A6-5400K running Win10, and several laptops running everything from XP to Win10 (X5+)

  2. #12
    Join Date
    Mar 2016
    Location
    Pikesville, Maryland
    Posts
    133

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    Quote Originally Posted by ac7kh View Post
    Well, Thanks to Jay, a new motherboard for my M4GA arrived today (it is amazing all the goodies Jay has for sale). Plugged it in and was greeted with "cass??" on a clear green screen (the video chip on the old MB must have been bad too). So taking the plunge, I mounted one of the original drives and got "diskette?" prompt but when I put in the LS-DOS disk it ate it. Good thing I have a backup or so I thought. Pulled that drive and plugged in the second one and it ate the backup, gerrrrr. Went to the M3 and made another, if I didn't have a FreHD this could have been a disaster, pulled the second drive out, plugged in my Mitsubishi 4851 1/2 height and tried with a M3 Boot. This time it worked, pulled that disk put in the LS-DOS disk and finally that worked. Then following up, I started checking out the keyboard and found the letter "M" key doesn't work. So now I am off to watch Ian's video on how to clean keys and see if that will fix it or will I have to order some new keys (will keep at least one spare) and will also be watching eBay for drives. Does anyone know if the drive cable on a M4GA has all it's teeth or will I have to order one to get DSDD ????

    Cheers

    Ross
    The cable with the "'missing teeth" simply does the drive selection - so both drives don't need any jumpers or terminating resistors on them --- you could also use a cable with "all teeth" - but then you have to physically set each drive via jumpers and termination

  3. #13

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    Quote Originally Posted by TRS-Ian View Post
    Hi Ross, the RS232 on the FreHD is not implemented for TRS-80 use. I know that may sound odd but it was original put there as a diagnostic aid when debugging FreHD during the alpha and beta test stages.

    Best thing for you would be to fix the power problem and get your system running reliably, then fix the RS232 chips.

    Actually, I had the intent to use the RS232. I started writing the driver for LSDOS, but got distracted... If someone wants to write this driver, please contact me and I can pass what I had. It's not that hard to do, but I really have no time for this at the moment. [And Ian is right, it was used initially as a debug port when writing the FreHD code]

    -Fred

  4. #14

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    Well the Saga continues, What with a brain transplant of a M4GA MB and a keyboard, from Jay (Thanks Jay), two replacement floppies plus a FreHD, you would think the world would be nice and rosy but NO the "new" keyboard is now acting weird, sometimes keys work, sometimes the same keys don't and sometimes a single press gives 4 to 6 of the characters. So back to the work bench to start checking key switches.
    Collection: TRS-80 Model 3 w/autoboot FreHD, TRS-80 Model 4 (X2), TI-99/4a (X2) w/PEB, Timex Sinclair ZX-81 w 16K module, Raspberry PI (X5), 1u eServer running Linux, Intel Brick Computer running Linux, Dell Optiplex 160 (X2) 1 running Win7, 1 running Linux, Dell Optiplex 755 running Win10, Mini MAC (Apple)(X2), a hacked together AMD A6-5400K running Win10, and several laptops running everything from XP to Win10 (X5+)

  5. #15
    Join Date
    Mar 2016
    Location
    Pikesville, Maryland
    Posts
    133

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    Quote Originally Posted by ac7kh View Post
    Well the Saga continues, What with a brain transplant of a M4GA MB and a keyboard, from Jay (Thanks Jay), two replacement floppies plus a FreHD, you would think the world would be nice and rosy but NO the "new" keyboard is now acting weird, sometimes keys work, sometimes the same keys don't and sometimes a single press gives 4 to 6 of the characters. So back to the work bench to start checking key switches.
    If you think the keyboard is defective you can return it for refund. Jay

  6. #16

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    No Jay I will not be sending it back, just stock up on key switches in case I need them.

    Ross
    Collection: TRS-80 Model 3 w/autoboot FreHD, TRS-80 Model 4 (X2), TI-99/4a (X2) w/PEB, Timex Sinclair ZX-81 w 16K module, Raspberry PI (X5), 1u eServer running Linux, Intel Brick Computer running Linux, Dell Optiplex 160 (X2) 1 running Win7, 1 running Linux, Dell Optiplex 755 running Win10, Mini MAC (Apple)(X2), a hacked together AMD A6-5400K running Win10, and several laptops running everything from XP to Win10 (X5+)

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