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286 really that rare?

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    #16
    I had never given it that much thought. I had always considered the '286 machines to be just another beige box in the 40-year procession of them. It so happens my first "PC" was a 286 clone which I bought from one of those tine mom-and-pop operations that advertised in the Bay Area classifieds. It had perhaps 1M, maybe 2M of RAM and a 10 or 20 meg disk. It ran DOS (fortified by 4DOS and a bunch of utilities from SimTel), and Coherent, until I was compelled to buy a 386sx at the beginning of December 91 so I could run Linux (boot and root, no login). I liked the 286 well enough, and the 386 was nice (and had 4MB RAM), but I had no sentiment for either machine like I had for the cranky OSI I had as a kid.

    Objectively, I know that these machines are outside my "imprinting" window, but I still have a hard time getting my head around the fact that some folks are sentimental for these machines, which I always regarded as lacking in personality.

    Still, given the numbers of these machines, I am surprised it's so hard to find one.
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      #17
      The realistic possibility I could imagine software with different optimization paths for "below 386" and "386+", where the "386+" path assumed "386DX+" and used 32-bit memory accesses gratuitiously. On a narrow-bus SX system, that could be a big hit.

      I could imagine chipset/mainboard design optimization being a thing, but a 386SX is close enough electrically that if you made a world-beating 286 motherboard, it would make sense to tweak it to package it as a 386SX as well/instead.

      More practically, I could see it as a full-system thing. The 286/20 at a given price point might have more memory, faster memory/fewer wait states, a faster drive, or a better graphics card than a 386SX/20.

      I feel like in a way, the PC world's backwards-compatibility obsession prevented the 286 from thriving. The people who bought them as basically a faster XT never meant much pressure on software designers to exploit the processor's features. By the time lots of people were grumbling about the 640k limit, they could just target the 386.

      If the AT had been a more blatant break with compatibility-- say, if it was MCA, or if its BIOS left you in protected mode at the end of boot-- the people who bought them would have likely been expecting the full 286 experience. They'd probably mostly ship with Unix-flavoured operating systems, or we'd see some much earlier forced attempts to get a protected-mode DOS-style product out the door.

      On the other hand, it's entirely possible by the time the AT hit the market, the PC/XT juggernaut was already unstoppable. In that scenario, the incompatible-AT ends up a niche product, and we'd have some non-IBM vendor eventually bolt a 286 into a 5160-compatible design but without necessarily the same market-shaping force to create a universal standard. I'm sort of thinking of something like the Olivetti M24/AT&T 6300, which already had a "sort of 16-bit" expansion slot.

      Given the long-lived market for "just a faster XT", I'm surprised that most 8086-class machines top out at 10 or maybe 12MHz. You could reasonably use faster embedded 80186/188/V40/V50 parts, and ignore their onboard peripherals to get even more mileage out of that architecture. It would be hilarious to see a modern 50MHz 80188 shoehorned into a conventional 8-bit ISA system, likely with the internal peripherals deactivated and a shedload of wait-states.

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        #18
        The Feb 8, 1988 Infoworld indicated that the 286 and 8086 were selling at about the same rate in 1987 with maybe 10% of the market going to the 386. By 1990, the 8086 had disappeared from the desktop market. Using roughly equivalent systems, the 286-20 was $300 cheaper than the 386SX-20 and $600 cheaper than the 386-20. Given the 1990 floppy only 286-16 AT clone cost $600, there wasn't much room to have a cheaper 8088/8086 design and I doubt anyone would have sprung for the cache needed to support a very high speed 8086. I did buy a 286 clone back in 1987; strangely, it was only about $50 more than the same companies XT-clone with an identical hard disk.

        The 286 had a good run despite the pressure of better CPUs dropping in price. The 286, unfortunately, had its market expansion hampered by the failure of the 16-bit protected mode OSes like OS/2 1.x and Xenix 286.

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          #19
          Originally posted by Eudimorphodon View Post

          Just out of curiosity, under what circumstances would the 286 be faster *per clock* than the 386sx? I mean, I guess an edge case you might be able to point to would be if the 386sx is running a memory manager that puts it in VM8086 mode, that might add a little latency compared to a 286 that has full hardware EMS support built into the motherboard chipset, but outside of that?

          There was this brief moment where 20 and 25mhz 80286s looked like a hot deal for running DOS software because you could get one for three or four hundred bucks less than a 16mhz 386sx which, yeah, they’d totally run faster than, but it was the clock speed difference responsible for that. It was all about price, though. And I wouldn’t necessarily say that people who chose the fast 286s were necessary wrong at the time because if you were happy with single-tasking DOS programs the premium Intel was milking out of the SX was pretty steep. (I upgraded my dog-slow 4.77mhz XT clone into an ad-hoc 12mhz 5162 wannabe sometime in 1989 or so because you could get the 286 motherboard for peanuts… $100-or so bucks?, while effectively the same board with a 386sx on it was around $500, minimum.

          Windows 3.0 was undoubtedly a major factor in killing the 286, but I think what really finished it off was AMD cloning the 386 and forcing prices to find their natural level. Without the monopoly premium on the silicon there’s zero reason to prefer the 286.
          I've benchmarked 286-16 vs 386sx-16 on identical setups. Same chipset, zero wait, no EMM. The 286 was consistently about 5-10% faster

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            #20
            Originally posted by Hak Foo View Post
            The realistic possibility I could imagine software with different optimization paths for "below 386" and "386+", where the "386+" path assumed "386DX+" and used 32-bit memory accesses gratuitiously. On a narrow-bus SX system, that could be a big hit.
            Are you suggesting that there's code that will run faster on an SX than on a DX? That code "written for the DX" would be "extra slow" on the SX than code written specifically for the SX?



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              #21
              The shift from 32-bit to 16-bit memory access could cut performance by about 10% and the 386SX motherboards tended to lack cache. The net result was that the 386SX was about 25% slower than the 386DX at the same clock speed on most code and much worse on the code that was taking advantage of the 386 instructions.

              The clock multiplied 386SX variants (486SLC) with built-in cache were amazing performers for the price though.

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                #22
                My 2c: charity stores like Salvation Army, Value Village and Goodwills used to be full of those PCs, but around 2010 they stopped accepting computer towers.

                What that means is that when an old person dies and their stuff is being sorted by estate/children, old PCs go straight to recycling centers.

                I recently needed a spare big AT power supply. I ended up paying about 115$ for it shipped. And you hope to score the whole working system for under 100$. It's not impossible, but very unlikely.

                Your best bet is to buy something as broken/not working for cheap and hope it's just shorted filtering tantalum capacitors on power lines.

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                  #23
                  Originally posted by Unknown_K View Post
                  Sure things changed with the 386 being 32 bit and having a much better memory manager setup but the 286 platform wasn't bad for its time.
                  In order to use the 286 (and its bigger address space) well, you had to structure your program around its limitations. Doing so then prevents you from using the 32-bit world efficiently. Basically, you are forced to paint yourself into a corner. Using it as a fast XT (with XMS for disk cache/overlay storage) provides a nice speed-up and retains compatibility in both directions.

                  Originally posted by whartung View Post
                  Are you suggesting that there's code that will run faster on an SX than on a DX? That code "written for the DX" would be "extra slow" on the SX than code written specifically for the SX?
                  If you treat a 386SX as a 386DX (i.e. use lots of 32-bit addressing and data), then performance will suffer. But if you treat it like a fast 286 instead (i.e. mostly 16-bit stuff), it will work quite well - and exceed the 286's capabilities.

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                    #24
                    A performance kneecap that even affected the 286 was that 8088 code didn't care a lot about code/data alignment on word boundaries, meaning if you were dealing with densely packed legacy code the CPU with the "wider" bus (like in the case of a 386DX vs. SX) might essentially need to do as many memory fetches as the narrower one. The CPUs had prefetch buffers that helped smooth this out, but it is a contributing factor why a full 386 sometimes wasn't *that* much faster than an SX (or 286) at a similar clock.

                    Conversely if you do have properly word-aligned 32 bit 386 code that shows off the 386 at its best then it will put the SX at its maximal disadvantage because it's basically always going to have to hitting the bus twice as often as the real thing.
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                      #25
                      So anything written with the XT/286 class CPU in mind should run well on a fast 286 which is the software you want to be using anyway.
                      What I collect: 68K/Early PPC Mac, DOS/Win 3.1 era machines, Amiga/ST, C64/128
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                      Boxed apps and games for the above systems
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                        #26
                        Were the 20 and 25 MHz 286s that common in North America? It seems like most of them were sold in Europe. Once the 386SX was introduced, Intel didn't want the 286 competing with it. The fastest 287 co-processor that Intel made was 12 MHz.

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                          #27
                          Originally posted by vwestlife View Post
                          Were the 20 and 25 MHz 286s that common in North America? It seems like most of them were sold in Europe. Once the 386SX was introduced, Intel didn't want the 286 competing with it. The fastest 287 co-processor that Intel made was 12 MHz.
                          I don't think they were. I don't ever recall using one back in the day

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                            #28
                            As many of you explained, many XT but more than 286 motherboards finished their days at "trash" or resold as scrap. I could remember some friends that used these ways, like myself.

                            In my case, we found an original IBM XT that was migrated to 286 and finally to 486. After it, it was replaced by a whole new Pentium class computer. So eventually it was sold cheap to somebody.

                            Now, these cases with the original board etc. cost more than my actual computer xD

                            As children, I remember many games that run fine with medium or fast 286 (12-20mhz), but Doom "forced" many of us to dream with 486 class computers.

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