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Re: [midatlanticretro] IMSAI CP/M progress

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  • Mike Loewen
    ... Using a combination of old and new technologies, I was finally able to get CP/M booted on the IMSAI and talking (correctly) to the terminal.
    Message 1 of 49 , Mar 8, 2010
      On Mon, 22 Feb 2010, Mike Loewen wrote:

      > My IMSAI came with a Morrow Disk Jockey 2D/B floppy controller, and a
      > box full of 8" diskettes. The original owner of the system did a lot of
      > hacking on it, and the boot disks are apparently set up for the Dynabyte
      > Naked Terminal display board that came with the system, for which I have
      > no documentation or keyboard. My first goal is to get the system to boot
      > to a serial console, using the serial port on the 2D/B.

      Using a combination of old and new technologies, I was finally able to
      get CP/M booted on the IMSAI and talking (correctly) to the terminal.

      http://sturgeon.css.psu.edu/~mloewen/Oldtech/IMSAI/IMSAI-07L.jpg

      Briefly:

      1. Used dosbox on Linux to run Dave Dunfield's IMDU to extract tracks 0.
      1, and 2-76 from the system disk image.

      2. Used dd on Linux to create 2 empty tracks (0 and 1) and concatenated
      them with tracks 2-76 to create a 77 track binary image with the same
      sector layout (9x1024). The original disk had 26x128 sectors on track 0
      and 9x1024 on tracks 1-76.

      3. Created a custom drive defition on Linux and used cpmtools to read the
      directory (cpmls) and extract the files from the image (cmpcp).

      4. Found the ASM source for the boot loader, CCP (ZCPR) and CBIOS as
      configured for the Dynabyte Naked Terminal board.

      5. Modified the CBIOS to use the 2D/B serial port as the console and
      assembled it under the sdltrs emulator to a HEX file.

      6. Used a load utility on Linux to convert the CBIOS HEX file to a binary
      file to be loaded at EB00H.

      7. Wrote a Linux utility to patch the new CBIOS binary file into the
      extracted track 1 in place of the old CBIOS, and concatenated tracks 0, 1
      and 2-76 to a single binary image.

      8. Used dosbox to run BIN2IMD to turn the binary image file back into an
      IMD file.

      9. Wrote the IMD back to diskette, and booted the IMSAI.

      Before this, I had made several attempts to directly patch code on the
      disk image, but was unable to get console input working properly.

      This is extremely convoluted, but it worked. :-) I'm going to do a
      detailed write-up and post it on my IMSAI page, for those interested in
      the nuts and bolts.


      Mike Loewen mloewen@...
      Old Technology http://sturgeon.css.psu.edu/~mloewen/Oldtech/
    • Evan Koblentz
      It s 4:37am, I should be sleeping. Anyway .... InfoAge may soon begin sheet rocking the ceiling of our new museum space + installing electrical circuits. This
      Message 49 of 49 , Jul 15, 2010
        It's 4:37am, I should be sleeping.

        Anyway ....

        InfoAge may soon begin sheet rocking the ceiling of our new museum space + installing electrical circuits.  This is good news because our space will look nicer, we won't have to worry about overhead work after we make new exhibits, and it'll be less space to heat/cool.

        Speaking of heating/cooling -- there's not yet any budget for that -- so in the summer we'll have several large fans, and in the winter we'll have electric space heaters.  Yes, I understand this is far from ideal.

        We have not yet finished painting the floor.  Still stuck at 80%.  Very little got done in the new museum space during the past few weeks because of my family situation, MARCHins having other commitments, other InfoAge tasks, etc. ....... but now we're ready to continue where we left off.

        This weekend, in addition to MARCH @ HOPE, InfoAge has a booth at the Fort Monmouth "Last Hoo-ah" event (the fort is closing.)  I will try to be there Friday and/or Sunday with a small demo (something simple like a C-64 or Apple II) and some literature.

        Also, there's an InfoAge WW II symposium on August 15, 1pm-5pm.  Price is $20 for adults and $10 for veterans/students.  Lectures include "How Radar Failed Us at Pearl Harbor"; "Story of the USS Murphy Tragedy Off the NJ Coast"; "Battle of the Beams -- Air War Over Britain"; "Army Signal Corps Tactical Communications Advances"; "Countering Hitler's Air Defense Systems"; and "The Birth of Digital Computing in WWII and Camp Evans' Role" (by yours truly.)


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