TI/99 4a clone

[seat safety switch]

I shouldn’t have said unobtainable. We’ve discovered that is doesn’t put out the right sounds that you’d expect from the 4A.

Example: the high pitch beep comes out as the low “donk” sound. Not sure if it’s the sound chip itself or something else in the board.

Dumb question, is the data bus around the right way? It's the same "reversed" MSB/LSB orientation as the TMS99xx.

I made an Arduino-and-breadboard tester and had to throw out* one of the SN76489s when I got my first batch of used ones, it sounded weird.

* I put it in my "weird chips" bin. Why would you throw out anything??

 

[rkrenicki]

I am happy to see that this project has continued! My TI-99 itch has come back, and I think I may try my hand at reworking this to fit inside of the original console.

 

[SteveV22FE]

Dan is starting work on the Mark 2 version of his clone! This is exactly what I have envisioned for years!!

Dan, if you're seeing this, please reach out to me.

 

[jltursan]

Cool!, is there any info available about this Mark 2?

 

[SteveV22FE]

Cool!, is there any info available about this Mark 2?

This is about it.

 

[jltursan]

Nice!, right from its To-Do list: "Redo the Board in an ATX form factor with PEB slots on board"

 

[danwerner21]

Sorry it has taken so long for me to reply . .

I did get started on this, but ran into some density problems and decided I needed to get some experience with 4 layer boards and the atx format in general before I could proceed much farther. . . So the mark 2 needs to wait just a bit longer while I learn a bit more.

however I have something else that might also be interesting to TI users . . . .

MiniCortex ATX

This is untested at this point, but I am probably going to order boards in a week or so after I spend some time double checking the design. I have built a smaller version of this board so I know the basic design does work, and is compatible with Stuart Conner's firmware and OS ports.

Dan

 

[danwerner21]

I shouldn’t have said unobtainable. We’ve discovered that is doesn’t put out the right sounds that you’d expect from the 4A.

Example: the high pitch beep comes out as the low “donk” sound. Not sure if it’s the sound chip itself or something else in the board.

I know I am really, really, really late replying to this (just re-reading the thread) -- but it sounds like you have J7 set wrong. There are multiple versions of the sound chip that need different clock rates to work properly. If the sound does not have the correct pitch, J7 (sound clock select) is probably the culprit.