Tandy Video Mod

[drignor]

Cool, thanks for going through the trouble, Alan.

[ZiggyTheHamster]

Chuckphd53 - did you ever put together any of these?

[GHiero]

I would definitely do this mod and buy a board, a neat, clean, small board whose behavior can be changed from canonical PCjr. to Tandy and back with a flip of a switch.

[Chuckphd53]

I am happy to pick up the mantle on these boards..

This would be Alans call of course..''

chuck

[Chuckphd53]

if there is enough interest I will do a board layout and get some made...

[alanh]

I'll document the project on my site this week and update the link here when finished. I have some boards made already + some quantity of parts. I can send what I have to anyone willing to take up the effort. They are SMT however with a TSSOP-20 (16v8), by-pass cap (0603) and a single dip-switch. The 16v8 needs to be pre-programmed before mounting and I plan on keeping my socket adapter.

The other difficult thing about the replacement is the existing DIP has to be de-soldered. Even with a descent sucker, it's a bit of a pain to take the original chip out ('157 as I recall) and replace it with a socket for either the mod (switchable) or the original '157. So I have a stick of replacement chips I had planned on sending with the boards so people could a) just cut the original chip out and desolder individual pins, and b) have a genuine replacement for reverting to original condition (+socket). Would be nice to provide a kit that has a socket, '157, and the new populated board all together.

-A

[Chuckphd53]

Anything I can do for the group let me know....

[ZiggyTheHamster]

I don't have a way to program PALs, but 0603/TSSOP are not a problem for me. Same with desoldering the existing chip.

From what I can tell, PAL programmers are not hard to build. Alternatively, maybe we can redesign this using small SMT 74 series logic to make it easier to assemble (not requiring programming).

[Sharkey1331]

Alanh or Chuckphd53: Do you have any Tandy mod boards to sell? Alternatively, do you have a programmed PLD to sell? I can get the boards easily enough from OshPark, but don't have a way to program the PLD.

Thanks!
Jason

[Chuckphd53]

send me an email pcjr@terradock.com I can help