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[Altair Computer Club] Re: 8800BT

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  • Steve
    Your description of the sys clg looks right to me. By the way, MITS also made a turnkey board with no RAM on board, for its fully loaded business systems.
    Message 1 of 7 , Aug 29, 2006
      Your description of the sys clg looks right to me. By the way, MITS
      also made a turnkey board with no RAM on board, for its fully loaded
      business systems. They came out shortly before MITS' doors closed.

      The Altair disk systems used hard sectoring, so you need 32-sector
      diskettes. Check the message archives- I think someone in this group
      had some for sale a while back. The 5" drives required 16 sectors.
      All Icom systems (8" and 5") were soft-sectored.

      Sometimes you can buy non-MITS memory boards pretty cheaply on ebay.
      That may be the easiest way to add more RAM. Godbout, Morrow, SDS,
      and many others made a 64K board. Bear in mind that Altair 500-C
      BASIC running the hard disk accounting packages didn't require a full
      64K, and 48K was enough to run Wordstar.

      Steve
      =================================

      --- In altaircomputerclub@yahoogroups.com, "Larry D. Pyeatt"
      <pyeatt@...> wrote:
      >
      >
      > Thanks for the info and pointer to the files section of the Altair
      > Computer Club.
      > I didn't know that it was there. It has a lot of stuff that I had
      not seen.
      >
      > I compared my Turnkey Board with the 88-SYS CLG mod directions, and
      I
      > am very sure that it has that mod.
      >
      > Let's see if I understand how the memory works. I haven't looked
      at
      > the schematics
      > yet, but by possibly incorrect deduction, I arrived at the
      following.
      > Assuming a factory
      > Turnkey board, without the 88-SYS CLG mod, then the memory map in
      > an 8800BT would be:
      >
      > 0000-03FF PROM provided by the Turnkey Board
      > (Writing to Port FF makes this disappear,
      allowing
      > access to
      > 1K more RAM)
      > 0000-3FFF 16MCS RAM board (overlaps with Phantom PROM)
      > 4000-7FFF 16MCS RAM board (if present)
      > 8000-BFFF 16MCS RAM board (if present)
      > C000-CFFF 4MCS RAM board (if present)
      > D000-DFFF 4MCS RAM board (if present)
      > E000-EFFF 4MCS RAM board (if present)
      > F000-F3FF 1MCS RAM board (if present)
      > F400-F7FF 1MCS RAM board (if present)
      > F800-FBFF 1MCS RAM board (if present)
      > FC00-FFFF RAM provided by the Turnkey Board. This RAM conflicts
      with
      > any other RAM mapped into these locations,
      because
      > accessing
      > it does not generate the PHANTOM signal. The
      Stack
      > resides here.
      >
      > The above takes 9 slots, just for RAM, and costs a LOT. So, the 88-
      SYS
      > CLG disables
      > the RAM provided by the Turnkey Board, allowing four 16MCS RAM
      boards:
      >
      > 0000-03FF PROM provided by the Turnkey Board
      > (Writing to Port FF makes this disappear,
      allowing
      > access to
      > 1K more RAM)
      > 0000-3FFF 16MCS RAM board (overlaps with Phantom PROM)
      > 4000-7FFF 16MCS RAM board (if present)
      > 8000-BFFF 16MCS RAM board (if present)
      > C000-FFFF 16MCS RAM board (MUST BE PRESENT, because the stack
      > starts at FFFF and grows down. Can be smaller
      than 16K.
      > RAM on Turnkey Board must be disabled to prevent
      smoke.)
      >
      > With the 88-SYS CLG, the memory board at the top of memory can be
      > smaller than 16K. It only needs to be big enough to hold the
      stack.
      >
      > Did I get it right?
      >
      > I would like to be able to run Disk BASIC, so I am considering just
      > building a
      > 64K RAM board, using newer technology. Basically, just the voltage
      > regulator,
      > an 8 by 64K RAM chip, and a few gates. That may be a lot easier
      and cheaper
      > than finding three more 16MCS boards.
      >
      > I'm fairly certain that I got the FD400 drive. Maybe I can find a
      bare
      > FD500 and
      > swap the drive hardware. What type of disks should I buy?
      >
      > Thanks again, Steve. You have been a great help!
      >
      >
      > Steve wrote:
      >
      > > Larry,
      > >
      > > For further information on Altair's front panel switches, and for
      > > possible sources, look in the FILES folder, at
      > > FILES > STEVE'S FILES > 'Sources for 8800b toggle switches.pdf' .
      > >
      > > A Turnkey board that has the System Kludge (88-SYS CLG) mod
      installed
      > > should work OK with less than 64K, if you have some additional RAM
      > > at the top. For example, a 4K board addressed from 60K to 64K. If
      > > you can confirm that your board actually has this mod installed
      > > (there were a couple of other mods that were similar), then it
      > > shouldn't be too hard to un-mod it. If you need a better copy of
      the
      > > instruction sheet than what Tom has posted, I'll upload a bigger
      one
      > > to our FILES folder. Andy Kessel may have some suggestions too.
      > >
      > > If you plan to use Altair Disk BASIC, I think you'll need at least
      > > 32K of RAM for the early versions and 48K for later versions.
      > >
      > > Pertecs FD400 drives usually had a white front door and used a
      > > stepper motor to spin the disk. The FD500s had black doors and a
      > > 115VAC spindle motor , which was much more reliable. If the 400's
      > > stepper stalled, the TIP driver transistors would usually smoke if
      > > power wasn't quickly removed by opening the door. Other than the
      > > spindle motors, the drives were interchangeable.
      > >
      > > Steve
      > > ===============================
      > >
      >
      > --
      > Larry D. Pyeatt, PhD.
      > pyeatt@...
      > http://www.cs.ttu.edu/~pyeatt
      >
    • mfeberhard
      Steve, Is the 88-SYS CLG mod documentation posted online? If so, where? If not, can you post it here, in the files section someplace? Thanks! Martin E.
      Message 2 of 7 , Aug 11, 2014
        Steve,

        Is the 88-SYS CLG mod documentation posted online? If so, where? If not, can you post it here, in the files section someplace?

        Thanks!

        Martin E.
      • wtsnet
        virtualaltair.com Anything Altair http://www.virtualaltair.com/virtualaltair.com/vac_altair_turnkey_module.asp
        Message 3 of 7 , Aug 11, 2014
          virtualaltair.com Anything Altair

           

        • alltare
          I just uploaded 88-SYS CLG for TURMON board.jpg to FILES STEVE S FILES. It s the same document that Tom has posted on his site
          Message 4 of 7 , Aug 12, 2014
            I just uploaded "88-SYS CLG for TURMON board.jpg" to FILES > STEVE'S FILES.  It's the same document that Tom has posted on his site (virtualaltair.com).Steve===================
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