Ah, what the heck. I finally got a round tuit. That makes it time for ... another Refurb Weekend.
Saturday, March 30, 2024
Refurb weekend: Data General/One (and the worst LCD in the world)
Monday, March 18, 2024
After 41 years, my first assembly program on my first computer, the Tomy Tutor
The other reason is that there was never really a simple way to do it. Even when I found out what CPU was actually inside (incredibly a 16-bit TMS 9995, an evolved version of the TMS 9900 in the Texas Instruments 99/4 and 99/4A), there was never a Tomy assembler, and other than its small amount of scratchpad RAM (256 bytes) the entirety of the Tutor's 16K of memory is tied up in the 9918ANL VDP video chip. That sort of architecture was typical for the family, but that also means that almost everything is stored in non-executable VDP RAM, so short of burning your own cartridge EPROMs there's no way to actually create and run a machine language program on the Tutor. The first flashcart for the Tutor didn't exist until around 2016 and it was still all ROM; furthermore, while the 99/4A could have its CPU-addressable RAM expanded (as well as the 99/8, its unreleased successor to which the Tomy Tutor is closely related), there wasn't ever a Tutor RAM expansion cartridge either until very recently. But now there are multiple homebrew options even for obscure home computers like this one, and at last I've got my own assembly language program finally running on it.
And it's all done with its own, better I/O routines (if I do say my own better self) as a basis for bigger projects. But first, a little tour of the Tutor itself, and then we'll dig in.