PG Designs M100 RAM Expansion

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PG Designs made several ram expansion boards for Model 100 that ranged from 32K to 224K.
These devices added extra ram to a Model 100 in the form of 32K "banks", where each bank was essentially a whole separate computer. You use the extra ram by switching from one bank to another, and while in one bank you generally only have access to the files in that bank. It's almost as if you put one Model 100 away and pulled out a different one. The PG Designs ram adds to the original ram inside the Model 100, so if you have 32K installed in the Model 100, and add the the 224K PG Designs, you have a total of 256K available, in the form of 8 banks, where bank 1 is the original internal ram, and banks 2-8 are provided by the expansion.


Installing the bank-switch utility

  1. Back up any files you care about currently on the M100.
  2. Hard reset the M100 (wipe the ram): CTRL+BREAK+RESET
  3. Use Teeny (or any TPDD client) and dlplus (or any TPDD server) to copy "MENU.BA" to the M100.
    (There are other ways you could transfer this file, but what you can NOT do is transfer MENU.BA the usual way directly with TELCOM, or even with LOAD "COM:...", like you could with any other .BA file. The file is a .BA basic program, but it contains machine language data that breaks normal serial transfer. It must be treated like a binary file to get it installed, and then executed.)
  4. Run MENU.BA
    You will answer some questions.
    You will see "saving and moving program".
    Ignore the “FC error in 4” error.
    It will then delete the first 5 lines of itself and re-run itself.
    The program is now in lowmem.
    It will also remove the next 5 lines of itself.

At this point the program IS installed, though you can't see it.
It is an invisible program called 0MENU. (number zero, not letter oh)

To activate, type 0MENU at the main menu and hit Enter.

You should now see a new menu, and you can switch to another bank.

0MENU is only installed in bank 1 at this point.

When you switch to another bank, 0MENU won’t exist there at first, and so you can't use it to switch back.

You can get back to bank 1, or any other bank, one of two ways:

  • One way is you can just power off and back on, which puts you back in bank 1. And since bank 1 has 0MENU installed, you can use it go from there to any other.
  • Another way is to repeat the 0MENU install procedure in every bank, so you have 0MENU in every bank.


0MENU also allows you to copy files from any bank that has 0MENU to any other bank that has 0MENU.

You can use INVISO.BA to make the program visible (MENU.BA), or invisible again (0MENU).


Find or create an mp3 cassette version of 0menu.

Create a 0menu injector similar to the teeny or floppy installers?

Scan the paper manual for the 32K version.

Credits / References

Thanks to Stephen Adolph for documenting the install and usage procedures and providing a pdf scan of the manual to an early 32k (single bank) model.



There are several bits of info about the PG Designs ram expansion all through different places in this archive. Here are some examples, but look through the whole thing yourself:
LIB-13-REVIEWS/PGD64K.REV (see floppyco.txt from the here) 0menu v1.3 0menu v2.01 (from Richard Hanson below) See the RICHARD HANSON section

PG Design Data Transfer Utility v2.01 for 32K - 224K RAM Expansion units.
Please note: The MENU.BA file is not in ASCII due to embeded machine language code. You must download with xmodem or greater. The INVISO.BA file is ASCII.

Apparently these were also sold under the name Enterprise Systems? Maybe re-seller?

Compatibility issue, and work-around, with the stock Tandy dos for TPDD and TPDD-2: