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The Last HOPE - and why exhibits are worth doing

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  • B. Degnan
    My exhibit at HOPE: http://www.vintagecomputer.net/osborne/thm_osborne1b_w-docs2.JPG I took an Osborne 1b ROM rev 1.4 to the 2600 magazine The Last HOPE
    Message 1 of 1 , Jul 20, 2008
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      My exhibit at HOPE:
      http://www.vintagecomputer.net/osborne/thm_osborne1b_w-docs2.JPG

      I took an Osborne 1b ROM rev 1.4 to the 2600 magazine "The Last HOPE"
      convention on July 19th, as part of a vintage computer demo. I originally
      planned to exhibit an "original" version of the Osborne 1 (with the tan
      chassis, also model rev v. 1.4), but that one had a bad A drive. "Insert
      Disk in drive A and press RETURN" is as far as I could get.
      http://www.vintagecomputer.net/osborne/thm_osborne1a_boot-error.JPG

      Prior to the event I did attempt to replace the drive. First I had to see
      what was going on inside of the machine. It takes about 10 minutes to
      completely disassemble an Osborne 1, if you have a longish phillips-head
      screwdriver. There are only three types of screws and clearly this machine
      was made for field repairs.

      Anyway.. once I got the system completely apart so that I could get to the
      disk drives I learned that the drive gets it's 5v and 12v power from the
      data cable, and there is no separate power connector like your
      run-of-the-mill IBM PC drive. The drive's controller card had special
      electronics for drawing voltage through certain pins in the dataline, etc.

      In short, one cannot simply swap out an Osborne 1 disk drive and replace
      with the drive from a Kaypro II or IBM PC. My choices appeared to be
      either sacrifice a working drive and swap the electronics from the bad
      Osborne drive, or simply find a replacement drive.

      It was 11 PM, I had to be up by 6AM, and so I decided to take the Model 1b
      instead.

      Now here is why all of that trouble was worth it. At The Last Hope, I ran
      into a guy who used to be an Osborne service tech. I got into discussing
      the system I left at home with the bad A drive. He told me that a special
      key combination, when pressed upon boot, would cause the system to boot
      from the "B" drive. CP/M needs to boot from A, so A becomes B, B becomes A
      when this bypass is activated. He tried for quite a while, but could not
      find the key combo. But now I knew it was possible.

      After he left I found the answer on http://vintage-computer.com/vcform/

      SHIFT "

      ...when pressed upon boot will cause the system to swap the drives.

      The B drive (now "A") DOES boot, and now I can use the system with one
      drive at least.

      http://www.vintagecomputer.net/osborne/thm_osborne1a_system-menu.JPG

      This is just one good reason to exhibit at VCF E this year. If you exhibit
      you invariably run into someone with a tidbit of knowledge useful to your
      projects, and visa versa.

      bd
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