[HN Gopher] Texas Instruments' Biggest Blunder: The TMS9900 Micr...
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Texas Instruments' Biggest Blunder: The TMS9900 Microprocessor
(2017)
Author : YakBizzarro
Score : 72 points
Date : 2022-11-15 13:07 UTC (1 days ago)
(HTM) web link (spectrum.ieee.org)
(TXT) w3m dump (spectrum.ieee.org)
| McGlockenshire wrote:
| A while back I decided to build a homebrew system based on the
| TMS99105A CPU, thanks both to this article and to Ben Eater's
| terrific videos. It's a pretty cool platform. It's been my first
| real exposure to working in assembly language and I've been
| having a blast.
|
| Due to the way the it provides bus status signals, you can
| effectively build a system with completely separate memory
| address spaces for executable code and data ... and a another
| separate address space for both of those when you use the built-
| in memory mapper support. It gets more fun if you can take
| advantage of the way it handles a subset of unimplemented
| opcodes: it shelves the current workspace and treats the opcode
| like a branch call. The 990/12 minicomputer and the 99110A CPU
| use this technique, branded "Macrostore," to add floating point
| instructions to the platform.
|
| That's three separate memory address spaces each for instructions
| and data... and another entirely separate address space for I/O
| devices!
|
| I really like this thing and one fine day I'll actually have
| something concrete enough to publish an article about it. If you
| want to learn more about the clever and insane things that
| 9900-series fans are doing, your best bet is heading over to the
| Atari Age forums where there are a bunch of homebrew software and
| hardware projects in progress:
| https://forums.atariage.com/forum/119-ti-994a-development/
|
| Somewhere buried in there you'll also find commentary from TI
| employees and other insiders about this article.
| jhallenworld wrote:
| I remember looking at this book at my local library when I was a
| kid:
|
| https://archive.org/details/tibook_how-to-build-your-own-wor...
|
| So I knew about the CPU before I knew about the home computer..
|
| Oh, one other thing I remembered: there were integrated injection
| logic (I2L) versions of the 9900: the SBP9900 (this was bugging
| me because the I thought the TMS9900 was I2L, but it's NMOS):
|
| https://www.cpushack.com/tag/sbp9900/
|
| Here is a datasheet, the I/O structures are interesting:
|
| https://source.z2data.com/2020/11/29/8/20/42/604/RSELSA00012...
|
| Runs off of 500 mA at 1V.
| NonNefarious wrote:
| jes wrote:
| I never knew that TI's DS-990[1] series of minicomputers was
| created for Ramada Inns. It was one of the first computers I used
| intensively and I thought it was great. I think I wrote code in
| almost every language they supported. Good times, and the TI
| documentation was quite good, in my view.
|
| Hit me with your WP (Workspace Pointer) register, baby!
|
| [1] https://en.wikipedia.org/wiki/TI-990
| blep_ wrote:
| As a person from The Future, making a whole new computer model
| specifically for one specific hotel chain is _really weird_ to
| me.
| shrubble wrote:
| Look up the Singer System 10...
| jes wrote:
| My former mentor-at-a-distance Eli Goldratt used to say
| "Yesterday's solutions are today's historical curiosities."
|
| I think he might have gotten that from a better-known
| aphorism: "Yesterday's solutions are today's problems."
|
| Thanks for your comment. It was fun and inspired other fun
| comments.
| AdamH12113 wrote:
| This was only a few years past the era where every computer
| was a full custom installation that took up a large part of a
| room.
| tomcam wrote:
| Just wait until you learn about the Hilton offset:segment
| addressing mode and Marriott memory mapping
| foobarian wrote:
| Many other things happened that way. My favorite were all
| these systems research efforts where entire operating
| systems, network file systems, directory services, etc were
| developed within individual companies or CS departments and
| unleashed upon the staff :). MIT Athena, anyone?
| retrocryptid wrote:
| So... a couple of things:
|
| 1. Rhines implies TI never made an 8-bit CPU, but tried to
| "leapfrog" the industry and go direct to 16-bit. This isn't
| exactly true. TI competed with Intel on the Datapoint contract,
| but didn't win. Intel went on to evolve the 8008 into the 8080
| and turn it into a commercial product. But TI shelved it's
| TMX1795 project. My guess is they already had a nice chip
| business and didn't need to risk anything on building a "pie in
| the sky" project like a single-chip microprocessor. I mean,
| imagine, a CPU on a single chip! How unrealistic!
|
| https://www.righto.com/2015/05/the-texas-instruments-tmx-179...
|
| 2. The 9900 series was't a loser by the standards of the day.
| Sure, it didn't get picked up by IBM, which made it a loser by
| 1981 standards. But by 1978, it was picking up some design wins
| because for less than $100k, you could buy a 990 mini-computer
| with a full-fledged development system (Assembler, Linker, Pascal
| Compiler, etc.) The 8080 was a lot cheaper in volume, but
| development was slightly more difficult. Intel's 8080 development
| systems weren't really that great, though by early 1980 they were
| light years ahead of TI (you could get an official Intel
| development system for around $35k IIRC.)
|
| As an interesting aside, Marinchip Systems shipped a S-100 board
| with a 9900 (9940? 9995?) CPU. But it didn't take off, so they
| started selling software and changed their name to AutoCAD.
|
| http://www.s100computers.com/Hardware%20Folder/Marinchip/990...
|
| 3. The 99105 / 99110 (with a much larger address space) was
| definitely on the drawing board in '78. IBM probably asked "hey.
| what chips do you have right now?"
|
| 4. Everyone likes to rag on the 9900 for being a memory-to-memory
| architecture. But in the day, the plan was to put your register
| file in bipolar memory. This was before we all got the RISC
| religion, and it wasn't so obviously bad.
|
| 5. This article only scratches the surface of the dysfunction
| that was the TI-99/4. But... the industry learned a lot of what
| NOT to do by watching TI try to deliver a game console.
|
| But to recap. Sure. The 9900 had some problems. The 9980 kept
| having more and more problems. But the 9995 wasn't half bad. And
| the 99105 & 99110 weren't bad at all.
| tomcam wrote:
| Analysis: true
|
| Username checks out bigly
| dtagames wrote:
| The chip, along with the rest of the TI-99/4A has been fully
| emulated in JS in this fantastic project you can run in the
| browser. It even has a debugger and all the original cartridge
| software, too.
|
| https://js99er.net/#/
| nsxwolf wrote:
| There's no better or faster way to experiment with a TI-99/4A
| today. Besides the great hardware emulation, a huge collection
| of the software released for the platform is available right
| there on the site.
| dang wrote:
| Discussed at the time (of the article):
|
| _Texas Instruments' Biggest Blunder: The TMS9900 Microprocessor_
| - https://news.ycombinator.com/item?id=14619360 - June 2017 (125
| comments)
| PaulHoule wrote:
| The TI-99/4A was unique among 1980s computers for having a
| distinctly different memory architecture. The 2022 Commander x16
| similarly uses IO ports to access video RAM and eliminates some
| bottlenecks that kind of machine had but it has generous RAM, not
| a pittance.
| renewedrebecca wrote:
| There were actually a ton of computers that used the same video
| chip (or its successors) that the TI-99/4A used. The entire
| MSX/MSX-2 series for one.
|
| Also, to be slightly pedantic, the X-16 doesn't have IO ports.
| It's using a 65C02 processor, where all I/O is memory mapped.
| bogantech wrote:
| > Also, to be slightly pedantic, the X-16 doesn't have IO
| ports. It's using a 65C02 processor, where all I/O is memory
| mapped.
|
| The video ram is not on the 65C02's bus apparently and is
| accessed through a set of registers which must slow down
| things quite a bit, you get plenty of video memory this way
| though I guess. Must be what they mean by "IO Ports"
|
| https://github.com/commanderx16/x16-docs/blob/master/VERA%20.
| ..
| chasil wrote:
| I actually used the DNOS operating system on the mini line
| where the 9900 originated.
|
| I flew around the country ripping these out of industrial
| equipment dealerships (replacing them with SCO), so I never saw
| any of the DNOS networking features.
|
| https://en.wikipedia.org/wiki/TI-DNOS
| NoNoSong wrote:
| Stratoscope wrote:
| The article doesn't mention the TI 770 and later 771 Intelligent
| Terminal which were based on the TMS9900. The 771 with two 8"
| floppy drives is shown in this brochure:
|
| http://bitsavers.informatik.uni-stuttgart.de/pdf/ti/terminal...
|
| The 770 was the terminal part only, with tape cartridge drives in
| the two bays above the keyboard:
|
| http://bitsavers.informatik.uni-stuttgart.de/pdf/ti/terminal...
|
| They are the same machine other than the storage.
|
| Here's a look at the inside:
|
| https://forums.atariage.com/topic/312144-ti-771-intelligent-...
|
| The 770 was oriented toward business forms and interaction built
| with TI's TPL 700 (Terminal Programming Language).
|
| I put the 770 and TPL to good use at Tymshare in the 1970s. I'd
| been called down to our Houston office to design and build yet
| another prompt-and-response Teletype UI for one of our business
| customers.
|
| Being in Texas, the office just happened to have a TI 770 in a
| back room. When I saw it, I stayed up all night and used TPL to
| implement our data input forms onscreen instead of the Teletype
| interaction.
|
| Our sales guy loved it, and more importantly, so did our
| customers. The app went on to make the company a good bit of
| money for those days.
|
| One thing I didn't find in my web search: a TPL manual! If anyone
| finds one, please post it in a reply. Thanks!
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(page generated 2022-11-16 23:00 UTC)