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Thread: TI 99/4a

  1. #31
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    The British counterpart to the TI-99/4A would be the Sinclair QL though many of the QL's problems were caused by compromises designed to make the QL into a portable system with built-in display and not adjusting the design when it no longer was going to be that. Every decision for both the TI-99 and QL seems reasonable but the cumulative effects of all the decisions resulted in a system difficult to sell at a profit.

  2. #32
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    Quote Originally Posted by Gary C View Post
    Ees 'avin a go at the Sinclair now !

    In the UK it was all we could get when it came out, and very glad I was for it, even with 1K

    TI99/4a would have cost about 500 in 1981 in the UK or 69 for the ZX.
    I guess I was unnecessarily harsh on the Sinclair as I can still use it to this day in my office:

    IMG_20190822_115556.jpg

    -- Brian

    Systems: Amstad PCW 8256, Apple IIe/II+/GS/Mac+/Mac 512k, Atari 800/520STFM, Commodore 64/128/Amiga 3000/PET 4032/SX-64, IBM PS/1 2121-B82, Kaypro II, Osborne 1, Tandy 1000 SX, TI-99/4A, Timex Sinclair 1000, TRS-80 Color Computer 3/Model 4 GA

  3. #33

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    The TI-99/4 at least showed IBM how an industry giant should not make a 16-bit personal computer.

    And remember that TI put Commodore out of the calculator business, so Commodore was all too happy to return the favor by doing everything they could to put TI out of the computer business.

  4. #34
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    Quote Originally Posted by krebizfan View Post
    Every decision for both the TI-99 and QL seems reasonable but the cumulative effects of all the decisions resulted in a system difficult to sell at a profit.
    I dunno, the whole ROM/GROM/MPX memory and bus architecture of the 99/4A is just plain wack from pretty much any angle. If everything were equal then, sure, a 3Mhz 9900 verses a 1Mhz 6502 sounds like should have been a pretty easy win (but in fact is nowhere close to a slam dunk, since the 9900's instruction timings aren't particularly impressive and all the CPU "registers" reside in external RAM), but even if that were true designing the system so it essentially has to run everything under an interpreter completely negates any point of having the more expensive CPU in it. And compared to a "sane" shared memory system like an Apple II or VIC-20 the 99/4a is hideously over-complicated and needs more chips for worse performance. Having just the VDP RAM might make a vague amount of sense if it were just a game console, but trying to turn it into a computer (and not completing work on an apropos 8-bit version of the 9900) made it the most expensive ridiculously overengineered game console ever simply masquerading as a computer.

    Compared to something like a Sinclair ZX-81 I can at least respect the ZX for coming by its limitations honestly; it's a Z-80 tied to the cheapest off the shelf ROM and a RAM chips they could get away with and held together with some very clever software; it's not really a practical design for a "real" computer but as an exercise in minimalism it's actually pretty amazing and it *did* get a starter computer into the hands of a lot of people while still actually being profitable to churn out. (Not much profit, mind you, but you could still sell it for a few bucks more than it cost in parts.) The TI was intentionally crippled at great cost and TI just kept doubling down on bad decisions until it broke the company. Which makes it a fascinating artifact of history, at least?
    My Retro-computing YouTube Channel (updates... eventually?): Paleozoic PCs

  5. #35
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    Part of the design for the TI-99/4A was to use the 9900 with some emulation layers to simulate a planned but never built low cost variant of the 9900. Made sense for testing prototypes but the cost of materials required retail prices of about $600 to break even.

    Take a look at the TMS 9995 which took the 9900 base design with an added 256 bytes of RAM on chip and made it fit in a standard 40 pin (cheap) package. Imagine the cost savings if the TI-99/4A had been using one of those chips instead of the complex 9900 plus scratchpad RAM design. With a little work, I think that could have resulted in a slightly faster TI-99 which could have been sold at $200 while making a profit. Still a strange computer and not a great value but much improved compared to what TI tried.
    Last edited by krebizfan; June 19th, 2020 at 01:31 PM.

  6. #36

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    Quote Originally Posted by krebizfan View Post
    Take a look at the TMS 9995 which took the 9900 base design with an added 256 bytes of RAM on chip and made it fit in a standard 40 pin (cheap) package.
    That was the CPU used in three unreleased prototype computers: TI-99/2, a super cheap Timex-Sinclair competitor with a chiclet keyboard, black & white video, and no sound; the TI-99/5 (a.k.a. TI-99/4B), an updated version of the 99/4A with 48K RAM, built-in speech synthesizer, Hexbus interface, and RGB video output; and the TI-99/8, with 64K RAM and a better keyboard.

    The TMS 9995 did end up in the Tomy Tutor, which was heavily based on the TI-99/4A but designed as a children's educational computer, released in 1982 in Japan and 1983 in the USA but a marketplace failure.

  7. #37
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    Quote Originally Posted by ngtwolf View Post
    I guess I was unnecessarily harsh on the Sinclair as I can still use it to this day in my office:

    IMG_20190822_115556.jpg



    nice one.
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