Help with completely emulating CompuMate in Stella

[+stephena]

So, I'm about to do a new release of Stella, and I'm already thinking ahead to what I'll work on next I've decided to give the CompuMate a go. Stella currently has complete emulation of the built-in software in the CompuMate cart, but doesn't support loading/saving to cassette at all. And I don't have an actual CompuMate, so it's going to be somewhat difficult to proceed. There are several ways forward:

1. I could solicit donations to buy a CompuMate, or you could donate one (see Stella donations page)
   
2. Someone with a working CompuMate and cassette player could save a program and send me the data
   

Let's go with option (2) for now. If someone could perhaps create a simple program on their CompuMate, save it to a blank tape, and somehow get me data on that tape (or send the tape itself), it would be a great help.

 

Also, if anyone has information on how the data is stored on tape, and/or any other information, it would be greatly appreciated. My initial goal is to be able to load and save simple programs. This leads into my overall goal of being able to load SongMate and PictureMate programs and have everything work correctly.

[+stephena]

So, no comments so far? Surely someone has considered properly emulating this at some point??

[Eckhard Stolberg]

According to Kevin Horton's 2600 mapper text the CompuMate uses bit 7 of SWCHA for tape input and bit 6 for tape output. When you press Func-H in the Stella CompuMate emulation, the screen flashes 8 times, so I assume the CompuMate always saves the entire 1K RAM to tape in steps of 256 bytes.

 

You could modify Stella to trap Func-H and Func-J. When Func-H gets pressed you would recored changes to bit 6 of SWCHA and how many cycles have passed since the last change. When Func-J gets pressed you could feed this information back into bit 7 of SWCHA. Maybe this would help to figure out how the CompuMate converts bytes to audio.

 

BTW, SongMate and PictureMate aren't real programs. They are just a collection of sample songs / pictures for the build-in music editor / paint program of the CompuMate ROM.

[+stephena]

According to Kevin Horton's 2600 mapper text the CompuMate uses bit 7 of SWCHA for tape input and bit 6 for tape output. When you press Func-H in the Stella CompuMate emulation, the screen flashes 8 times, so I assume the CompuMate always saves the entire 1K RAM to tape in steps of 256 bytes.

 

You could modify Stella to trap Func-H and Func-J. When Func-H gets pressed you would recored changes to bit 6 of SWCHA and how many cycles have passed since the last change. When Func-J gets pressed you could feed this information back into bit 7 of SWCHA. Maybe this would help to figure out how the CompuMate converts bytes to audio.

 

OK, I like this idea (use Stella to debug itself, so to speak). The only snag is that the CompuMate contains 2K RAM, not 1K.

 

BTW, SongMate and PictureMate aren't real programs. They are just a collection of sample songs / pictures for the build-in music editor / paint program of the CompuMate ROM.

 

OK, so accessing those files might be more complicated than I thought. Perhaps they're stored in a multi-load format similar to the Supercharger??

[Eckhard Stolberg]

OK, so accessing those files might be more complicated than I thought. Perhaps they're stored in a multi-load format similar to the Supercharger??

There are several loads on the SongMate and PictureMate tapes, but I don't think it's as complicated as the Supercharger format. A new load must always be triggered by the user pressing Func-H. It doesn't happen automatically. Also I don't think the CompuMate can load data to only certain parts of the RAM like the SC can.