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It was ahead of its time. It was the CPU inside my first personal computer. Unfortunately, the system that TI designed around the processor was a nutty architecture that severely limited the potential of the CPU.
Here's the text of an advertisement for a developer's board:
FREE YOURSELF FROM THE ONE BYTE WORLD. MOVE UP TO THE TWO BYTE TEXAS INSTRUMENTS TMS-9900 16-BIT MICROPROCESSOR — WITH OUR — "SUPER STARTER SYSTEM" — TEC-9900-SS. SHOWN ABOVE, FEATURES HARDWARE MULTIPLY AND DIVIDE, 69 MINI-COMPUTER INSTRUCTIONS, 7 ADDRESSING MODES, EXPANDABLE TO A FULL 65K BYTES; MONITOR, TMS 9900 CPU, RAM, P-ROM, E-PROM, PROGRAMMER ALL ON ONE P-C BOARD BASIC OPERATING SYSTEM AS LOW AS $299 UNASSEMBLED $399 ASSEMBLED AND TESTED EXPLICIT MANUAL INCLUDED OR AVAILABLE SEPARATELY AT $35, TO LEARN MORE . . .JUST TEAR OFF A PIECE OF THIS AD, PIN TO YOUR LETTERHEAD & RETURN TO TECHNICO OR CALL OUR HOTLINE 1-800/638-2893 TO RECEIVE FREE INFO-PACKAGE. —DESIGN & TECH SUPPORT BY ROSSE CORP.
This text is from an ad in Byte magazine on the internet archive:
Byte Magazine Volume 02 Number 05 - Interfacing : Free Download, Borrow, and Streaming : Internet Archive[^]
The difficult we do right away...
...the impossible takes slightly longer.
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Depends upon how bit your mouth is.
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I was unaware of that story, thanks. But it was the least expensive home computer at the time, so it was my first love.
The difficult we do right away...
...the impossible takes slightly longer.
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I know that feeling. It was the ZX Spectrum, for me.
"In testa che avete, Signor di Ceprano?"
-- Rigoletto
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Ah, the TI-99/4A. Had one myself, WAY back in the day.
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Yes, the sound chip was ahead of its time as well, never mind the fact that the machine did 16 colors in the display.
The difficult we do right away...
...the impossible takes slightly longer.
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Quote: Two bytes are better than one.
I miss that kind of advertising and the "artistic" pics/inuendo that were used in the day.
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Ahhh, what a trip down memory lane.
My first micro computer was the Heathkit H89 with the Z80 chip. Assembling the kit was kind of fun (if you like soldering what seemed like hundreds of tiny resistors and diodes, making custom cables by hand and trying not to splash solder onto the copper tracings on the mother board). Got to hand it to Heathkit, the instructions were clear, they had me test each sub-assembly to get rid of mistakes early. The machine booted up the first time I tried it. The clunk, clunk, clunk of the floppy drive as the heads were seeking the tracks, the buzz saw sound of the dot matrix printer, the smell of new wiring as it warmed up. Word processing and spreadsheets on the machine were simply amazing. I splurged and got a professional ball typewriter with a serial interface. I think it was a DEC typewriter. It weighed a good thirty pounds and did carriage returns with such force that it caused the printer stand I had bought for it to dance around the room like it was possessed. Using film ribbons, the print quality of the typewriter was first class. I subsequently moved the printer to my desk, which had more bulk to counter the carriage return forces.
Did some programming in basic. The kids pestered me to find or make games for the machine.
Ahhh, the good old days.
Thanks for the memories.
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ditto h89 yeah i think i still have it somewhere
"A little time, a little trouble, your better day"
Badfinger
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Yep, good times.
I built my first system (z80 based) in 1978. Bought an s100 bus backplane with power supply, a CPU card and a video card (connectes to TV - 16 lines of 64 characters). I wire wrapped a 4K RAM board and a dual port serial card. I didn't have any programming language at the time so I learned to program the z80 by the numbers (all I had at the time was the Zapple control monitor). I eventually wire wrapped a board to allow me to store programs on cassette recorder. This system grew until it ran CP/M, had 64K RAM and dual 8 inch floppies. I eventually picked up a Selectric typewriter mechanism and designed and wire wrapped a control board for it so my printouts would be pretty  . I think my last project was to wire wrap a board to control a Votrax speech synthesizer chip (phoneme based sound generation) so that I could have my computer talk. Definitely fun stuff!
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I cut my teeth on the TI990 minicomputer, from which the TMS9900 was derived. It has a first class operating system, hampered by the 16 bit address space. I wrote a device driver for a terminal running over RS 232 (it needed to be further away than their own VDUs could handle). That was fun.
Paul Sanders.
If I had more time, I would have written a shorter letter - Blaise Pascal.
Some of my best work is in the undo buffer.
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The TMS9900 was actually used in several different systems, by different divisions within TI. I helped write one of them, before I was reassigned to DX10, the OS built on the TI 990 minicomputer. Then, after leaving TI, I worked for Ryan-McFarland (RMC), which implemented an executive (would hesitate to call it an OS) which ran on the TMS9900-based 990/2 model. The 990/2 was sitting more-or-less dead in distributors' warehouses (DX10 did not run on it), and the RMC product made the 990/2 sellable in competition with low-end NCR offerings. The 990/2 was totally separate from the more famous 99/4, which was the product developed by a different TI division.
The TMS9900 was well ahead of its competitors (as the OP's ad quotation claims), but TI's focus was on different things. Being a diversified tech company has its drawbacks that highly focused companies can exploit.
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I used it on one project. Its claim to fame was rad hard parts were available. The same project used the original Mac toaster for documentation since it passed TEMPEST requirements.
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It's fun to revisit these advertisements from the good 'ol days. Speaking of old time advertisements, I remember the days of flipping through the hundreds of pages in "Computer Shopper", looking at all the cool stuff that was available. I remember back in 1991 as a new Lieutenant in the USAF, finally picking a "high end" PC and having to use two different credit cards to pay for it.
The good 'ol days indeed... 
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TMS-9900, is that the processor that had all its registers in RAM?
For ordinary processing, it was much slower than dedicated register logic within the CPU, but on the other hand: It makes interrupt handling extremely simple: Just change the address of the current register block to where the interrupt handler has its register block. I have the impression that TMS-9900 grew out of what we today would call an embedded processor line. In that segment, interrupt handling is often far more critical than processing speed.
And, you could have as many threads as you wanted, each with its own register block - again: With very rapid thread switching: Just set the register block address. As long as you don't run out of space, of course. Maybe you couldn't fit that many threads in 64K. 64K should be enough for everybody, though.
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Yes the registers in RAM were called the workspace. And in order to branch, you would use an instruction called Branch and Load Workspace Pointer, BLWP. This single instruction would transfer control to the specified address and load a specified address into the Workspace Pointer. Sort of a primitive way of giving functions their own stack space.
I don't recall the TMS-9900 being multithreaded. It only had real mode. Perhaps you're thinking of a different CPU?
The difficult we do right away...
...the impossible takes slightly longer.
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Richard Andrew x64 wrote: I don't recall the TMS-9900 being multithreaded. It only had real mode. Perhaps you're thinking of a different CPU?
Multithreading does not in itself require any hardware support at all. If you want preemptive multithreading, you need a thread switcher triggered by a clock interrupt to move the active register block pointer to the next one to receive attention. This goes well without any sort of virtualization or non-real mode. In a simple world, threads in a workspace are just different points where something is happening, in a single world, not in different virtual worlds.
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Wordle 852 5/6
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Wordle 852 4/6
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Wordle 852 3/6
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Wordle 852 3/6
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