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Thread: IBM 5150 possible inconsistency?

  1. #21

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    My 5150 PC, made in 1986, came with a 130-watt XT power supply when I got it from its original owner in the mid-1990s. But I don't know if it came that way from the factory or if the XT power supply was a later replacement.

  2. #22
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    It's certainly possible that by 1986 IBM had hit the "Using up the last of the parts" stage of production and tossed in some 5160 power supplies to get the last few units off the end of the line, but, again, without actual provenance to prove it that's just speculation. (The 5162, aka XT/286, itself existed solely to soak up leftover 5160 case parts on the runup to the introduction of the PS/2 line.)
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  3. #23
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    Quote Originally Posted by Eudimorphodon View Post
    (The 5162, aka XT/286, itself existed solely to soak up leftover 5160 case parts on the runup to the introduction of the PS/2 line.)
    Anything authoritative on that ?

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    Quote Originally Posted by modem7 View Post
    Anything authoritative on that ?
    I think it's pretty obvious that IBM would never write that down in a manual, so, no. But I'm pretty sure it's a conclusion that appeared in more than one contemporary magazine at the time.

    Edit: Of course, yeah, it's also possible that this guy was right, and the reason it was in the 5160 case wasn't to soak up leftovers, but because IBM got cold feet at the last minute and decided *specifically* to kneecap a motherboard the designers originally intended to put in a more AT-slot compatible box in whatever small, arbitrary way they could quickly do to help make sure they could still position the 5170 as a "premium" product. Either of these theories pack sufficient explanatory power to account for a product that otherwise doesn't make a whole lot of sense.
    Last edited by Eudimorphodon; October 26th, 2020 at 02:09 PM.
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  5. #25
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    Quote Originally Posted by Eudimorphodon View Post
    But I'm pretty sure it's a conclusion that appeared in more than one contemporary magazine at the time.
    If you do find such a magazine article, let me know, and I will add it to [here].

  6. #26

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    If the XT-286 was such a flop, then why did the entire PC clone industry copy it and turn it into the "Baby AT" form factor, which lasted over a decade? And as MinusZeroDegrees notes, "Claims that IBM created the IBM 5162 just so that it could use up stocks of IBM 5160 (IBM XT) cases are pure speculation. It seems unlikely to me, considering the cost of system development (including technical documentation), administration, testing, and marketing. Consider too, that the IBM 5162 was introduced 7 months before IBM decided to withdraw the IBM 5160 from the market":

    http://minuszerodegrees.net/5162/misc/5162_basics.htm

  7. #27
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    Quote Originally Posted by vwestlife View Post
    If the XT-286 was such a flop, then why did the entire PC clone industry copy it and turn it into the "Baby AT" form factor, which lasted over a decade?
    It seems like a stretch to me to claim the "Entire clone industry copied it"; the sum total of the "innovation" is a 286 board that fits inside a case with XT-position-ed holes. There are 286 motherboards with holes and slot-spacing that fit the 5150 too, it seems likely someone would have thought of this idea at some point. Also, most "Baby AT" cases, as opposed to XT-cases-with-AT-processor-boards in them, are tall enough to take full AT height cards; IBM definitely didn't invent *that*, so if they "invented" the form factor they only invented part of it.

    I mean, yeah, maybe it did encourage the industry to churn out more 16 bit bus cards in the XT height, to such a degree that full-height AT boards are more the exception than the rule?

    (In which case you can argue that IBM's move backfired, since it legitimized half-***ed upgrades to a greater degree than they would have been otherwise.)

    And as MinusZeroDegrees notes, "Claims that IBM created the IBM 5162 just so that it could use up stocks of IBM 5160 (IBM XT) cases are pure speculation. It seems unlikely to me, considering the cost of system development (including technical documentation), administration, testing, and marketing. Consider too, that the IBM 5162 was introduced 7 months before IBM decided to withdraw the IBM 5160 from the market"
    But that is an equally speculative statement likewise based on no privileged insight to the actual motivations which were driving the company. There are *plenty* of reasons why IBM would introduce the machine without discontinuing the 5160, the least of which being is that they were still aiming to clear the decks by whatever means possible. Another convoluted idea I've heard about the machine is they cooked it up so accounts with rigid procurement procedures would have an easier from-an-accounting-viewpoint option in place of the plain 5160. (IE, the "slip it in under the radar" theory.)

    And re: it being a flop, everyone seems to agree it is "rare", it was only on the market for 10 months, and reviews of the machine are lukewarm at best, so... what's a flop? Anyone have any numbers how many 5162s were sold compared to the PCjr?
    Last edited by Eudimorphodon; October 26th, 2020 at 03:41 PM.
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  8. #28

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    5162 is a great machine. I hesitate to speculate on its true provenance, but I'm happy to own one. Full height AT cards not fitting is not really a big problem for me

  9. #29
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    Also, here's a really good counterargument to the assertion that IBM "invented" the Baby AT. Here's a capsule review of a PC Limited 286/12 in the July 1986 issue of PC Mag. One of the features noted by the reviewers is the machine has a footprint "about 20% smaller than that of the PC AT yet still includes the eight expansion slots". And, wouldn't you know it, apparently in 2015 Michael Dell was feeling nostalgic for the good old days and decided to post a photo of that machine's motherboard to Twitter.

    PC_Limited_286.jpg

    That sure looks like a "Baby AT" motherboard, and this is the same month the 5162 came out. So unless Dell was copying the future...

    Edit: Also, just paging further through the magazine I noticed an ad for an "ALR PC2/286" which looks like a *classic* early "Baby AT", IE, it's styled like an AT but the case is a little smaller, and it even has a 135 watt power supply. Poked around, and this roundup of "80286-based XT Compatibles from February 1987 that pretty much seems to exist solely to review the 5162 goes so far as to say "The ALR PC2E/10Mhz might rate as an IBM PC-XT Model 286 clone, except that the early 1986 announcement of the base version of the machine, ALR's PC2/286, predated IBM's improved XT by many months". So... another piece of evidence that if anything IBM was following, not leading, when it comes to the "Baby AT".

    (The ALR machine is a *little* goofy because it only has five expansion slots; they apparently on their budget couldn't fit all the AT guts on an XT-size board at early 1986 levels of integration. But the *case* has the standard 8 slot holes and it's an XT factor board, so strictly speaking I'd say it counts.)
    Last edited by Eudimorphodon; October 26th, 2020 at 04:41 PM.
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  10. #30

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    Quote Originally Posted by Eudimorphodon View Post
    That sure looks like a "Baby AT" motherboard, and this is the same month the 5162 came out. So unless Dell was copying the future...
    It looks about a quarter-inch too wide, with extra overhang past the keyboard port. Maybe it'd fit in some clone cases, but not in an IBM XT case where that clearance between the motherboard and power supply is very tight.

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