Don’t Mess With Texas – The TI-99/4A Megademo






[Thanks to Gregg for the tip!]

18 thoughts on “Don’t Mess With Texas – The TI-99/4A Megademo

        1. “Console” is the correct idiom for TI-99/4A just as “control deck” was the idiom for the NES. Not the same as “console” as a distinction from personal computer.

  1. Ah, the TMS9900 in there was a very interesting architecture, from the times when RAM was much faster than CPU.

    The 16 “registers” were just a region on RAM pointed at by a register on the CPU. Very “fast” (we’re talking a few MHz) context switches and stack juggling!

  2. Nice one. I’ve got a boxed 99/4A sitting under my bed. It’s working but I really have no idea what to do with it. Perhaps it’s time to flog it? Let’s hope this article jacks up the price :)

  3. Oh, I started on the 4/A when I was 7 years old. I loved the thing. Funny story… the program you use to load a BASIC program from a cassette tape is larger than the program used to save to tape. So, at some point if your BASIC program hits the right size, you can save it to tape but never load it again. My “huge” dungeon game at a few hundred LOC disappeared forever in this way. The machine also went nuts and created the most beautiful graphics ever (compared to the normal stuff on the machine) when you did try to load such a program. It’s hard to believe it wasn’t intentional… the top half of the screen was a shaded blue gradient, the bottom was solid green. The text somehow was squashed very flat so it looked like you were typing on a field into the distance. There was also some kind of shaded sphere (?) or something somewhere. It was a huge disappointment to lose my prized game code, but the way in which the machine crashed helped make up for it.

  4. The 32K expansion was on its own card, not in the floppy controller. The 99 has seen some recent activity in fancy upgrades. The F18A is an FPGA clone of the video chip, with VGA output, 80 column mode and other goodies added, but alas, not yet a full bitmap mode with every pixel individually colorable.

    The F18A VDP is a direct replacement for *any* microcomputer or game console that used the TMS 9918A, TMS 9929A or TMS 9919A. The 18A outputs NTSC composite while the 29A does PAL component video. The rarely used 19A did PAL composite. AFAIK TI never made an NTSC component version, which would have been the TMS 9928A.

    So if you have an old MSX1 computer kicking around, or anything else using any of those three TI VDPs you can give it VGA output with this VDP. Using the upgraded features will of course require writing new software. Dunno if it can replace the earlier non-A versions as used in the TI-99/4 – which had no lowercase character set.

  5. Very nice demo, brings back a lot of memories, sounds like they had a speech synthesizer on it and looks like they used a few call load (peek pokes) for some of the effects. I think the 994a is responsible for my love of technology today, it was my first introduction to programming in both basic and logo. This was the first computer I used to connect to BBS s with and because it was made by TI I was also introduced to the format of the instruction manuals that they still use in data sheets today. If it wasn’t for the slight taint from Bill Cosby’s involvement it would be perfect.

  6. Heh. I remember plugging in the ‘firehose’ cable for the PEB to run MS Multimate in 48K of RAM cut the poor computer’s speed in half. Imagine having a third of your RAM at the end of a two-foot cable in another box!

    1. I dunno maybe you had a bad one! Adding that 32k ram expansion opens up the 4/a into a usable personal computer and lets you use languages like assembly, fourth, c and more to get better performance.. I have a 1mb SAMS card in one of my 99/4a systems which has that base 32k and the rest is addressable in C, fourth and RXB (a newer extended basic) There is also a new 32k sidecar card for 35$ so you don’t even need the big box to run the software that needs that extra ram. Or the NanoPEB which added 32k, rs232 and a cfcard floppy emu.

      1. No, it worked fine, but having part of the RAM at the other end of the equivalent of a two foot long(?) PCB causes substantial latency issues. There is a reason, after all, why CPU’s and RAM are always as close as possible on a motherboard.

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