The Texas Instrument TI 99/4A was a very succesful computer. A large number ROM cartridges (36 KB each) were developped for this computer, as the popular Extended Basic.
Up to seven peripherals could be connected : 32 KB RAM extension, RS232c, Disk controler (90 KB per disk, up to 3 disk-drives), speech synthetiser, Peripheral Expansion box, and so on... One item of note is that the bus architecture for the Peripheral Expansion box (PE) was the basis for the NuBus used in the later Macintosh computers.
Contributors : Stephen Boutillette
Ben Yates says :
The TI VDP had 16K of dedicated VRAM, outside of the CPU RAM memory map.
The 99/4A has 4 VDP modes :
1. Graphic I (32x24, 255 redefineable characters, 16 colors, 1 background and 1 foreground color for each character set of 8 characters, 8x8 character matrix)
2. Text mode (40x24, foreground/background colors out of 16)
3. Multicolor (weird 48 x 64 mode, 4x4 unicolor character matrix)
4. Bitmap - same as 1, except 768 characters and each character can have a foreground and background color (of 16) for each pixel row of that character.
David Stites adds:
You list the TI 99/4a as being released in June 1979. At about that time I
purchased a TI 99/4 for around $700. Besides the built-in BASIC and the
firmware cartridges it had a third function called an Equation Calculator. I
never used it and when the computer went insane they replaced it with the
/4a for $50. The /4a didn't have the Equation Calculator.
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I had one of these as a kid. Sadly, I could never get it to work
Friday 4th March 2022
In September, 1979, I went to work at Texas Instruments in Lubbock, Texas, where the TI-99/4 and 99/4A was mostly manufactured. I was an electronic technician and did soldering and wire-wrap on prototypes in development, mostly software cartridges and add-on devices, as well as worked in testing, repair, burn-in (each new system was left on for several days, I think it was, then re-tested). And I helped train people on the assembly line. I did the wire-wrap prototype version of the speech synthesizer module$ a female engineer designed it$her name escapes me at the moment. .That speech synthesizer was a big deal for its time. She and I were the only two women in that module (and most of the rest of TI) who weren''t assembly line workers
Even though I worked on those computers, I could not afford to buy one for myself! Lordy, they were about $1,700 with all the extras such as the cassette tape drive, if I remember correctly, a fortune back then. But I did have a system at work to use! Much different than programming in FORTRAN on a mainframe!
In those days, another "module" or modular building at TI actually repaired people''s broken calculators and mailed them back to the user. Imagine that.
TI had these automated mail robots that followed a special painted line on the floor, in and out of modules and up and down the big hallway. We used to put stuff in front of them to see what would stop them and what wouldn''t. For 1979, it all was very futuristic to me.
Later, I moved to the Front End module to make more money, where I ran a boron/phosphorus ion implant machine, one of the several hundred processes in creating semiconductor chips. The implant machines were these huge particle accelerators that were the crankiest machines I ever worked with. The chips have multiple layers, and these machines placed a positive or negative charge on the unmasked areas of a chip''s layer. We made the first 256k memory chips there! Then I went back to college after I made enough money, and left TI and Lubbock, which were both good to me.
Friday 18th August 2017
Loretta M. (California, USA)
Ahhh the old tank TI 99/4A. So well built and so underappreciated. It actually plays games well and many of its educational software like Plato and the GROM carts were quite good for their time. If it only weren''t for that infernal PEB. That monstrosity is just a lump on the desk. Shame Custodio Malilong doesn''t make the fabulous microPEB anymore. Such a great device and so small. But if anything, he deserves great recognition for his device and making the TI more useable.