Texas Instruments TI-99/4a
In the 1970s, Texas Instruments was huge. They absolutely owned the calculator market, manufactured a variety of chips and ICs and it seemed inevitable that they would enter the personal computer market, perhaps also coming to dominate it as well.
TI introduced their first personal computer in 1979 and it it was called the TI-99/4. Yes, that is an absolutely horrendous name. I suppose it matched the naming they used on their calculators, such as the TI-30 above, but I still think it’s bad. Then again, 800, 64 and II aren’t exactly catchy names either, although they are easier to say.
The TI-99/4 did not sell well. It had a cramped, chiclet keyboard and rather high price of $1150 at launch (over $5000 in 2025).
TI gave it another go with the revised TI-99/4a in 1981, doubling down on the terrible name and only adding a small, lowercase ‘a’ to indicate a vastly better computer at a more affordable price of $525 (about $1800 in 2025).
Improvements included a full-stroke keyboard, better graphics and an expansion system.
Design
The case design had a serious, metallic silver industrial design, which I quite like. It looks much better than the toy-like Commodore 64 and is much more compact than the Atari 800.
Later editions use white/light gray/beige1 plastic case that was likely cheaper to manufacture. It also looks cool, but less sophisticated.
The keyboard is somewhat cramped having to fit into the space previously occupied by the chiclets. The tiny Enter key is a shame.
The right side wastes a lot of space with the large horizontal slot that you would slide cartridges into. If they’d made this a vertical slot, perhaps the keyboard could have been enlarged.
It used the standard Atari-style joystick port, but since it had a different pin layout Atari-style joysticks were not actually compatible.
A splash screen is displayed when you turn it on:
Internals
The CPU is a TMS9900 running at 3Mhz, also made by TI. This CPU was first introduced in 1976 and is actually quite powerful. It was even used in some minicomputers and is technically a 16-bit CPU, unlike the 8-bit 6502, Z80 and 6809 used by most competitors. It’s 3Mhz clock speed is also faster than most of those, which usually hovered around 1-2Mhz.
Its graphics used the TMS9918A Video Display Processor (VDP), which was rather powerful for the time. It could output up to 256x192 pixels with up to 15 colors. Plus there were 32 sprites. This was better than the Atari 800, which only could do two colors at that resolution and only had up to 5 sprites. The C64 would debut a year later with similar graphics specs to the TI-99/4a.
A similar version of this VDP, the TMS9928, was used in the ColecoVision (and Adam) systems.
The system came with 16K of RAM and it had a rather unusual memory layout that forced memory access to go through the VDP. There was a 32K RAM expander available from TI to get it to 48K, but the RAM situation with this thing was weird and I don't fully understand it.
For sound, the TMS9919 (another TI chip) was used. It could produce 3 voices and was a good chip that was used in a lot of systems such as the ColecoVision, Sega Master System, Genesis, PCjr and much more.
BASIC
It had a two versions of BASIC: TI BASIC and Extended BASIC. TI BASIC was built into the TI-99/4a, but it was slow and limited.
Extended BASIC was a cartridge and was faster with many more commands, including better use of the graphics.
I remember seeing programs for the TI-99/4a printed in Compute! magazine, even in 1985, but I also seem to recall that they usually required Extended BASIC.
Peripherals
Nearly all of the TI-99/4a computers that I’ve seen for sale only used a cassette drive for storage. This made sense because you could use any cassette record for this purpose, unlike the proprietary ones needed for the Atari and Commodores.
It looks to me like you could only use RF output to connect it to a TV, there was no higher quality monitor output.
From what I can tell, the Peripheral Expansion Box was needed in order to hook up a disk drive. This was a giant box that allowed for all sorts of expansion, as its name suggest, but it was pricey and it seems that few were sold. Finding one now is difficult.
Software
I just don’t recall seeing a lot of 3rd party software available for the TI-99/4a. In fact, TI even made it harder for manufacturers to make cartridges for the system, disabling some AtariSoft carts with a ROM update in some later systems.
The lack of an affordable disk drive option also hampered the ability for 3rd party developers to provide software for it.
Legacy
Commodore saw the weaknesses with the TI 99/4a, most notable that it was expensive to build, and decided to attack TI by starting a price war. Jack Tramiel never really forgave TI for doing the same thing to Commodore’s calculator business in the early 70s.
The VIC-20 was the first wave of attack and although it was a worse computer in every respect, its price got dropped to about $99 and TI felt compelled to stay competitive by lowering the price of the TI-99/4a, although not to that level.
The C64 was released in 1982 and it came in to deliver the killing stroke. The TI-99/4a was discontinued in October 1983 and soon was selling for as little as $49 during Christmas 1983! TI lost over $300 million in the 4th quarter of 1983. By March 1984, production ended2. That dumping of computers at $49 certainly inflated the sales total. The TI-99/4a ended up selling just under three million, not much less than the approximately four million 8-bit Atari computers that were sold in its lifetime.
Atari was took a lot of collateral damage in this price war. Because they also primarily sold to the home computer market, Atari felt they had to drop their prices to keep up, but the Atari 400 and 800 computers were just too expensive to produce causing Atari started losing money on them as well. It wasn’t until 1983 when the 600XL and 800XL were introduced that Atari had a home computer that was inexpensive to make and could compete with the C64, but by then it was too late to make much of a dent.
I see plenty of TI 99/4a computers for sale on Facebook Marketplace, but have so far resisted the urge to pick one up. I just don’t have room for more computers that I probably won’t really use.
However, I do have some random TI stuff in my pile of retro things such as these two cartridges:
Use the JS99’er TI-99/4a web browser emulator to play around with BASIC or play games.
For even more information about this somewhat unusual computer, including a bunch of cartridge ROMs to download and use with the emulator, check out the TI-99/4a-Pedia.
I’m not good with colors.
I’m surprised they kept producing them after they were discontinued.
From 1980 to 1982, I wrote three computer games for Avalon Hill (Conflict 2500, Voyager 1, and Controller). TRS-80, CoCo, Atari 800/400, Commodore PET, Apple II, and even the IBM PC.
NONE for the TI-99/4a.
It was not a bad computer. After all, it had sprites and a 16-bit CPU. But as I like to say, "Content is King, but Content Distribution is KING KONG."
THE TI-99/4a didn't easily support Cassette or Floppy software (required the extended BASIC cart), and Avalon Hill wouldn't build cartridges. On the tape games, they packed ALL versions onto a single cassette.
What the TI-99/4a had going for it was the LOGO programming language, which inspired me to create Atari FORTH Turtle Graphics for APX (Atari Program Exchange). I even demoed this to Seymour Papert, the inventor of LOGO..
I have commodore 64 and Atari 800, but 2 TI-99/4a computers. Loved it more back then and still do. Just easier to work with.