Looking for TRS-80 Model parts (and/or someone in the Phoenix, AZ area)

Peter Cetinski pete at pski.net
Tue May 2 18:07:39 CDT 2017

> Is the file for the PAL available to program new ones?  If the items are not registered, I can read out the equations.

Theses PAL equations specifically to allow the 6Mhz board to run Xenix 3 do not exist AFAIK.  I do have a PAL upgraded board but have not yet verified if it works.  If there is a way to safely reverse engineer the PALs, I might consider trying.

> Is a schematic for the 8 MHz board available?  Is there any other tech info about the differences between the original 6 MHz boards and the 8 MHz?  I only have a 6 MHz, but if I knew the differences, I'd contemplate hacking it into an 8 MHz, or just laying out a new 8 MHz board in Eagle.

I should expand a little more.  There are actually 2 different 6Mhz boards.  The first was a larger board that was part of the original Model 16 release.  The second was a smaller more compact board that I believe was released late in the 16s life and also along with the subsequent Model 16B.  This was required because the 16B cannot host outsized cards in its card cage.  Btw, You can use a 2nd or 3rd gen 68k board in a Model 16.  You can also use a 3rd gen board in a 16B.

Now, only the 2nd generation 6Mhz board can be upgraded with the appropriate PALs.  If you have the 1st gen board you will have to be happy with Xenix 1.x.  Which is fine because it's fun too and 98% of the Tandy Xenix software runs on Xenix 1.

The Model 16 service manual has the schematics of the 1st gen board.  The Tandy 6000 service manual has the schematics for the 3rd gen 8Mhz board.  I have not seen schematics for the 2nd gen 6Mhz board.  I suspect it can be found in the Model 16B service manual, but that manual is as rare as two-headed ballerina.  I have yet to find one.

> Will TRSDOS-16 work on the 8 MHz board?

Yes, the 8Mhz board will run all known Tandy 68k OSes.

More information about the cctalk mailing list