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TRS 80 model 4 and hard drive

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  • billdeg
    Hi - I am a relative newbie to the TRS 80 Model 4 world. I am seeking basic instructions for hooking up an external to trs 80 model 4...For example, do you
    Message 1 of 2 , Jun 14, 2005
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      Hi - I am a relative newbie to the TRS 80 Model 4 world. I am
      seeking basic instructions for hooking up an external to trs 80 model
      4...For example, do you attach a cable to the external drive port on
      the model 4 like a regular external disk? I cannot find any
      documentation (yet) that takes a person through the hardware
      installation and testing. I have some harddrives but I am unsure if
      they work and/or are configured to be receptive to the Model 4.

      Should Montezuma cp/m automatically detect the external hd or is
      there a program you'd need to run? does montezuma cp/m have
      harddrive support utilities? I have a number of versions of DOS's
      including Montezuma cp/m 2.2, but I am unsure which is best. I also
      have some ROMS that I can install into the Model 4 to automatically
      boot to the hard drive, but I don't want to move too
      quickly...looking for advice and doing research first. I will keep
      looking on this end.

      I have a Percom 5MB external disk drive that's my first candidate for
      the Model 4, but I have a few others to try as well. If there is a
      particular model(s) that's favored, please advise. I don't have any
      Tandy brand external drives.

      Thanks.

      Bill
    • Mike Loewen
      ... My second machine was a Model 4, but I was never able to afford a hard drive for it. I can answer a couple of your questions, though. The Model 4 does
      Message 2 of 2 , Jun 15, 2005
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        On Wed, 15 Jun 2005, billdeg wrote:

        > Hi - I am a relative newbie to the TRS 80 Model 4 world. I am
        > seeking basic instructions for hooking up an external to trs 80 model
        > 4...For example, do you attach a cable to the external drive port on
        > the model 4 like a regular external disk? I cannot find any
        > documentation (yet) that takes a person through the hardware
        > installation and testing. I have some harddrives but I am unsure if
        > they work and/or are configured to be receptive to the Model 4.

        My second machine was a Model 4, but I was never able to afford a hard
        drive for it. I can answer a couple of your questions, though. The Model
        4 does not have an internal hard drive controller: you have to hook up an
        external "primary" hard drive unit which has the controller installed. It
        connects to the system via a long ribbon cable to the IO bus connector on
        the bottom of the machine. Additional "secondary" hard drives may be
        connected to the primary. The drive itself was "hacked" onto the
        controller, to get the write protect circuitry to work. The drive
        housing:

        http://localhost/~mloewen/Oldtech/Harddrive1L.jpg

        ...has a pushbutton switch to enable/disable write protect, which
        required connection directly to the drive electronics. A document which
        tells you how to install different drives in the housing is here:

        http://www.trs-80.com/cgi-bin/downpatc.cgi?hdbubblerepair.zip

        The same site has a lot of hardware mod info:

        http://www.trs-80.com/trs80-ph.htm

        > Should Montezuma cp/m automatically detect the external hd or is
        > there a program you'd need to run? does montezuma cp/m have
        > harddrive support utilities? I have a number of versions of DOS's
        > including Montezuma cp/m 2.2, but I am unsure which is best. I also
        > have some ROMS that I can install into the Model 4 to automatically
        > boot to the hard drive, but I don't want to move too
        > quickly...looking for advice and doing research first. I will keep
        > looking on this end.

        Montezuma Micro was my favorite CP/M for the Model 4, because it could
        read/write just about any CP/M formatted diskette around. It did not have
        hard disk support built in, but they offered a driver for it:

        http://www.trs-80.com/cgi-bin/downcpm.cgi?mmrshdd.zip

        It's in disk image format, so you can fire up Tim Mann's xtrs emulator:

        http://www.tim-mann.org/xtrs.html

        or David Keil's Model III/4 emulator for Windows:

        http://discover-net.net/~dmkeil/trs80/model4.htm

        and create a diskette for your Model 4.

        > I have a Percom 5MB external disk drive that's my first candidate for
        > the Model 4, but I have a few others to try as well. If there is a
        > particular model(s) that's favored, please advise. I don't have any
        > Tandy brand external drives.

        The 5Mb primary drive in the picture is mine, but I believe the
        controller is defective. I've tried another drive in it (after rewiring)
        and it still doesn't work. I'd love to get a working drive on my Model 4.


        Mike Loewen mloewen@...
        The Dixie Lion Jazz Band http://ripsaw.cac.psu.edu/dixie.html
        The B9 Robot Builders Club B9-0014 http://ripsaw.cac.psu.edu/~mloewen/B9/
        Old Technology http://ripsaw.cac.psu.edu/~mloewen/Oldtech/
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