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Thread: Building a bootable external hard drive for a Macintosh Plus

  1. #11
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    Thanks.

    We'll the boot floppies turned up and I can confirm that the machine boots from floppy just fine. I ran the disk tools and the machine still won't recognise either of the Zip drives or a known working SCSI hard drive enclosure I have. How vulnerable are the SCSi interface IC's on this machine ? I believe it's an NCR5380 strapped straight on to the port.

  2. #12
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    Try a utility like Mt. Everything or SCSI Probe to see if the machine can see the drives. Older versions of Mac OS without PC Exchange can't work with non-Apple formatted disks, so you'll need to install it also.

    https://macintoshgarden.org/apps/mt-everything-155
    https://macintoshgarden.org/apps/scsiprobe
    https://macintoshgarden.org/apps/pc-exchange

  3. #13
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    Somewhere in my collection of old Mac stuff, I remember seeing a Hard Disk 20 Startup diskette.

    Perhaps you can search and find an image online?

    IIRC, the original Mac (Mac Plus in this case) could not discover and boot from any SCSI device. I think it needed a little help from that Hard Disk 20 Startup diskette.

    Good luck!

    smp

  4. #14
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    Quote Originally Posted by smp View Post
    Somewhere in my collection of old Mac stuff, I remember seeing a Hard Disk 20 Startup diskette.

    Perhaps you can search and find an image online?

    IIRC, the original Mac (Mac Plus in this case) could not discover and boot from any SCSI device. I think it needed a little help from that Hard Disk 20 Startup diskette.

    Good luck!

    smp
    There is utility called Apple SC disk setup that came on one of the OS disks called Disk Tools - I tried that and it scans the SCSI bus but does not find any of the devices I have attached so far.

  5. #15
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    I note that some of the older (pre version 3) ROM's had SCSI bugs in them - I'll check version of ROM that I have but does anyone know the nature of these 'bugs' ?

  6. #16
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    I believe I was mistaken.
    The original Mac did not have SCSI at all, and the original Hard Disk 20 attached to the external disk port.
    That would be the reason that a Hard Disk 20 Startup diskette would be needed.

    Sorry to confuse the issue for you!

    smp

  7. #17
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    Wouldn't this type of hard drive be the same that the Apple LISA uses?

  8. #18
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    One quirk of the Macintosh Plus compared to all later Macs is it doesn't provide termination power on the SCSI bus. That *could* be your issue with getting another drive to work, although with only one device attached you can sometimes get away with that being incorrect. Was the original dead drive set up to provide term power? (Many drives have a jumper for that.)
    My Retro-computing YouTube Channel (updates... eventually?): Paleozoic PCs

  9. #19
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    Quote Originally Posted by Eudimorphodon View Post
    One quirk of the Macintosh Plus compared to all later Macs is it doesn't provide termination power on the SCSI bus. That *could* be your issue with getting another drive to work, although with only one device attached you can sometimes get away with that being incorrect. Was the original dead drive set up to provide term power? (Many drives have a jumper for that.)
    Yes, I have tried with termination off and on but no difference with any of the drives I have. I'm beginning to thing I have a problem with the SCSI interface of the Macintosh Plus or its REALLY picky about the devices it has connected.

  10. #20
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    Quote Originally Posted by VERAULT View Post
    Wouldn't this type of hard drive be the same that the Apple LISA uses?
    No, the ProFile hard drive used the parallel port and the drive itself was proprietary, being a standard ST-506 drive with a custom Apple controller board.

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