3 ms·

I think you're being a bit harsh on the 286 with the benefit of hindsight. Remember that it hit the market in 1982. For it to have finished up in 1982, it lik

by hakfoo 6y ago

I think you're being a bit harsh on the 286 with the benefit of hindsight. Remember that it hit the market in 1982. For it to have finished up in 1982, it likely started development before or just as the original IBM PC hit the market. At the time, there wasn't a huge installed base of can't-afford-to-break 8086 code, or much of a precedent for backwards compatibility on a wholesale platform change for PCs. They may well have figured anyone trying to build a 286 system would be targeting a fully protected-mode OS, and the non-protected mode support was more of a stopgap for compatibility and bootstrap purposes.

anyfoo 6y ago
Thanks for pointing that out. I should clarify, I'm not calling it "brain-dead", that was famously Bill Gates (even noted so on the 286's Wikipedia page). I don't know or remember much about what the 286 was used for (besides IBM PS/2 systems), but I as well wouldn't be surprised if it was more targeted towards things like PBXs and industrial control, where Protected Mode without DOS compatibility made perfect sense...
- hakfoo 6y ago
  It feels like there were a lot of missteps for the embedded market which got crushed beneath the juggernaut of PC-compatible x86 chips. The big one was the 80186/188-- basically an 8086/8088 with a few onboard timers and serial controllers and a few enhanced instructions, but the new goodies were not in a PC-compatible design. You do see them quite often in embedded devices. The more interesting one was the 80376-- a 386 which was protected-mode only, but also missed other key features so it wasn't just "take a 386 oS and change the bootloader."
  - anyfoo 6y ago
    I'm familiar with both of those. In fact, I even own two 80186 PCs! Siemens PC-Ds, not IBM but DOS compatible. Marvelous machines. They even have MMUs made of custom logic chips, so they could not only run DOS, but also SINIX with full address space separation and supervisor mode (though no paging)... The non-compatible goodies of the 80186 play a big role in making it not IBM compatible, but other things as well. In many ways it was a bit better, e.g. high resolution (but monochrome) text and graphics, and no 640k barrier. The 80376 is an interesting beast because it got rid of 16bit support entirely--any 16bit segment descriptors were invalid.
    - anyfoo 6y ago
      Err, "custom MMUs made of individual logic chips" is what I meant. The MMUs are custom, the logic chips are just of the 74 variety.

by hakfoo 6y ago

anyfoo 6y ago

Thanks for pointing that out. I should clarify, I'm not calling it "brain-dead", that was famously Bill Gates (even noted so on the 286's Wikipedia page). I don't know or remember much about what the 286 was used for (besides IBM PS/2 systems), but I as well wouldn't be surprised if it was more targeted towards things like PBXs and industrial control, where Protected Mode without DOS compatibility made perfect sense...

hakfoo 6y ago
It feels like there were a lot of missteps for the embedded market which got crushed beneath the juggernaut of PC-compatible x86 chips. The big one was the 80186/188-- basically an 8086/8088 with a few onboard timers and serial controllers and a few enhanced instructions, but the new goodies were not in a PC-compatible design. You do see them quite often in embedded devices. The more interesting one was the 80376-- a 386 which was protected-mode only, but also missed other key features so it wasn't just "take a 386 oS and change the bootloader."
- anyfoo 6y ago
  I'm familiar with both of those. In fact, I even own two 80186 PCs! Siemens PC-Ds, not IBM but DOS compatible. Marvelous machines. They even have MMUs made of custom logic chips, so they could not only run DOS, but also SINIX with full address space separation and supervisor mode (though no paging)... The non-compatible goodies of the 80186 play a big role in making it not IBM compatible, but other things as well. In many ways it was a bit better, e.g. high resolution (but monochrome) text and graphics, and no 640k barrier. The 80376 is an interesting beast because it got rid of 16bit support entirely--any 16bit segment descriptors were invalid.
  - anyfoo 6y ago
    Err, "custom MMUs made of individual logic chips" is what I meant. The MMUs are custom, the logic chips are just of the 74 variety.