Image Map Image Map
Page 2 of 2 FirstFirst 12
Results 11 to 20 of 20

Thread: IBM 5x86 in a 486 system with PCI slots?

  1. #11
    Join Date
    Nov 2016
    Location
    Quakertown, Pennsylvania
    Posts
    323

    Default

    Hmm, interesting. I personally have yet to find a Socket 3 box that was actually built as an Am5x86 (mine has an Evergreen 5x86 upgrade) but I suppose that doesn't mean they don't exist.

  2. #12
    Join Date
    Sep 2003
    Location
    Ohio/USA
    Posts
    7,374
    Blog Entries
    2

    Default

    AMD kept making the am5x86-133 in SMT format for embedded controllers until 1999, which is why the last gasp 486 upgrade chips you see from Evergreen used surface mount chips. There were tons of embedded controls using that chip around until something faster and cheaper came around. Very few people would have bothered with a 486 upgrade in the late 1990's.
    What I collect: 68K/Early PPC Mac, DOS/Win 3.1 era machines, Amiga/ST, C64/128
    Nubus/ISA/VLB/MCA/EISA cards of all types
    Boxed apps and games for the above systems
    Analog video capture cards/software and complete systems

  3. #13
    Join Date
    Apr 2015
    Location
    Austin, Texas
    Posts
    1,404

    Default

    Quote Originally Posted by Unknown_K View Post
    Very few people would have bothered with a 486 upgrade in the late 1990's.
    I bought mine in the late 90s for a 486 SX/25 system because I was poor. IIRC it ran $99, but it was well worth it. Games that previously ran terrible (like Sim City 2000) then were very playable, and even Quake was somewhat playable at the lowest resolution setting.

  4. #14

    Default

    Quote Originally Posted by GiGaBiTe View Post
    The IBM is just a rebranded Cyrix 5x86, which was a cut down 6x86; Which was basically a Pentium class CPU.
    Unless I'm mistaken, the 6x86 came well after the 5x86 so calling the 5x86 a cut down version is like calling the 486 a cut down version of the Pentium.

    The 5x86 was a very buggy CPU, features it was advertised to have and be shipped with (like branch prediction) were disabled because it made the CPU very unstable. Even with all of the advanced features it was supposed to have being turned off in final silicon, it still suffered incompatibility issues with software and motherboards.
    Can you name examples of software incompatible with the Cyrix 5x86? I'm asking because my first computer* was an AST Advantage 611S with a 100 MHz Cyrix 5x86 and I don't recall any compatibility problems whatsoever.

    Quote Originally Posted by GiGaBiTe View Post
    The death knell of the 486 was when AMD stopped manufacturing the chips and Microsoft dropped support for it in Windows XP, which required the CMPXCHG and CPUID instructions. Though, technically you could run Windows XP on a 486 machine by using a POD63/83, it's just painfully slow.
    FWIW, CMPXCHG and CPUID are both available on 486 CPUs (CPUID only on later revisons).

    Quote Originally Posted by GiGaBiTe View Post
    I bought mine in the late 90s for a 486 SX/25 system because I was poor. IIRC it ran $99, but it was well worth it. Games that previously ran terrible (like Sim City 2000) then were very playable, and even Quake was somewhat playable at the lowest resolution setting.
    *It was actually my dad's computer and he bought it in august -95 (IIRC). I can still remember the feeling when I saw it boot up for the first time and hearing the Windows 95 start-up sound. Good times! Oh, and I ran Quake on it but it became unplayable as soon as 3 polygons where in view at the same time - at the second level with two Ogres and a torch on the wall it screached to a halt.

    My dad somehow got the impression that the Cyrix processor was better at floating point operations than the Pentium - I'm guessing the guy at the shop selling the computer told him that (or maybe the guy told him the truth but dad misunderstood/misremembered). Today I know better of course but my dad still believes it and I'm not going to argue with him - we both have fond memories of that computer and I don't think it's necessary to destroy his illusion. Anyway, I still have that computer and I've been meaning to set it up and use it again. The problem is as always lack of space.
    Looking for a cache card for the "ICL ErgoPRO C4/66d V"

  5. #15

    Default

    Quote Originally Posted by Krille View Post
    Unless I'm mistaken, the 6x86 came well after the 5x86 so calling the 5x86 a cut down version is like calling the 486 a cut down version of the Pentium.
    The Cyrix 5x86 was a cut-down version of the M1, which was the prototype of the 6x86:

    https://en.wikipedia.org/wiki/Cyrix_Cx5x86

    Quote Originally Posted by Wikipedia
    The Cyrix 5x86 processor, codename "M1sc", was based on a scaled-down version of the "M1" core used in the Cyrix 6x86, which provided 80% of the performance for a 50% decrease in transistors over the 6x86 design. It had the 32-bit memory bus of an ordinary 486 processor, but internally had much more in common with fifth-generation processors such as the Cyrix 6x86, the AMD K5, and the Intel Pentium, and even the sixth-generation Intel Pentium Pro.

  6. #16
    Join Date
    Sep 2008
    Location
    SE MI
    Posts
    3,909
    Blog Entries
    6

    Default

    IIRC, back in 1991 I purchased a 'bare bones' mini tower from a warehouse distributor located near O'Hare airport, just north of Chicago. The thing consisted of the case, P/S, and motherboard along with a 486SX-25, all for about $700, plus shipping. There wasn't much in the way of used peripherals, so I watched 'Computer Shopper' like a hawk. By the time I outfitted it in with a VGA card, color monitor, sound card, I/O card, RAM, keyboard, serial mouse, and Windows 3.0, I easily had 2K or so invested or maybe more, as I probably didn't want to remember. The modems were another thing back then. I had a 300 baud in my 1000SX and used that for a while and later settled on a 14.4K when the prices came down. It seems that every time you turned around someone had a new modem offer with a new features and speed (my last dial-up was a 56K external US Robotics with Mindspring until DSL showed its ugly head).

    The high end 486's were more or less out of the ball park, price-wise, for the casual user. One of my neighbor's taught CAD/CAM at Ford HQ and another was a mechanical engineer, who always had the current AutoCAD. Both always had the latest and greatest hardware and it was all made possible with the use of a tax write-off. So, the 486-25 served me well until I eventually landed an AMD Anthlon something or another. Since I had full use of PC's at the work place, it was hard to justify the expense of an elaborate personal computer thing at home. Then along came gaming.
    Surely not everyone was Kung-fu fighting

  7. #17

    Default

    Quote Originally Posted by vwestlife View Post
    The Cyrix 5x86 was a cut-down version of the M1, which was the prototype of the 6x86:

    https://en.wikipedia.org/wiki/Cyrix_Cx5x86
    I stand corrected (and I'm looking like a boob for not checking wikipedia before posting).
    Looking for a cache card for the "ICL ErgoPRO C4/66d V"

  8. #18
    Join Date
    Apr 2015
    Location
    Austin, Texas
    Posts
    1,404

    Default

    Quote Originally Posted by Krille View Post
    Can you name examples of software incompatible with the Cyrix 5x86? I'm asking because my first computer* was an AST Advantage 611S with a 100 MHz Cyrix 5x86 and I don't recall any compatibility problems whatsoever.
    The Cyrix 5x86 had an identity crisis. It wasn't a 486, and it wasn't quite a Pentium class processor either, putting it in limbo between both generations. The incompatibility issues stem from Cyrix PR touting it as a Pentium class processor, while it wasn't because it lacked several Pentium class instructions. This meant software that expected and was compiled for a Pentium would behave erratically.

    It also may have the infamous coma bug (the Cyrix equivalent of the Pentium F00F bug) that plagued the later 6x86 it was based on.

    The disabled features of the CPU were also a source of instability if enabled, which was possible because two tools were released to turn these features on and off.


    Quote Originally Posted by Krille View Post
    FWIW, CMPXCHG and CPUID are both available on 486 CPUs (CPUID only on later revisons).
    CMPXCHG is present on 486 systems, but not CMPXCHG8b, which Windows XP requires.

  9. #19

    Default

    Even the first-generation 6x86 won't run Windows XP because it is missing the necessary Pentium-compatible CPU ID.

  10. #20
    Join Date
    Nov 2016
    Location
    Quakertown, Pennsylvania
    Posts
    323

    Default

    Quote Originally Posted by vwestlife View Post
    Even the first-generation 6x86 won't run Windows XP because it is missing the necessary Pentium-compatible CPU ID.
    Where "Cyrix Instead" goes wrong!

Bookmarks

Posting Permissions

  • You may not post new threads
  • You may not post replies
  • You may not post attachments
  • You may not edit your posts
  •