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If your plan is to maintain decades of backwards compatibility with software from thousands of third parties, it's going to involve maintaining some originally-

If your plan is to maintain decades of backwards compatibility with software from thousands of third parties, it's going to involve maintaining some originally-undocumented behaviors that people exploited. That's what the wine developers got themselves into willingly, and it's what the Windows devs are increasingly shirking.

lozenge 4y ago
It's a question of priorities. Microsoft must have realised these edge cases were slowing development down and how many people really want to run a game or a CD burner software from 1998? Of course, this could all have been avoided with a proper universally understood spec like POSIX but it's too late for that now. (And POSIX never had graphics or sound support, which shows how big that project would be, with the churn of the PC hardware from 2D to 3D &etc) The hardware is also starting to protest - no way to run 16 bit instructions in x86_64 mode on a 64 bit processor.
- monocasa 4y ago
  You can run 16 bit code in long mode just fine. It's just a different GDT entry like 32 bit code is. Windows didn't cut 16 but mode because of the processor ut because they took the opportunity to increase the max HANDLE table size greater than 16 bit code can address.
  - messe 4y ago
    Just want to point out that not all 16-bit code can run unhindered in long mode. You can run 16-bit protected mode code. But long mode dropped the V8086 mode that made easily emulating 16-bit real mode possible.
    - AshamedCaptain 4y ago
      But you can switch in and out of long mode, so it is also possible to basically do whatever you want. And you also have hardware virtualization. It is a political decision to drop compatibility for 16 bit Windows and DOS (i.e. it was too much programming effort), don't blame the hardware.
- mmis1000 4y ago
  https://www.joelonsoftware.com/2000/05/24/strategy-letter-ii-chicken-and-egg-problems/ https://www.joelonsoftware.com/2000/05/24/strategy-letter-ii... I think this is the price they are(were?) willing to take. If they don't take backward compatibility seriously. Windows won't exist now at first place.

lozenge 4y ago

It's a question of priorities. Microsoft must have realised these edge cases were slowing development down and how many people really want to run a game or a CD burner software from 1998? Of course, this could all have been avoided with a proper universally understood spec like POSIX but it's too late for that now. (And POSIX never had graphics or sound support, which shows how big that project would be, with the churn of the PC hardware from 2D to 3D &etc) The hardware is also starting to protest - no way to run 16 bit instructions in x86_64 mode on a 64 bit processor.

monocasa 4y ago
You can run 16 bit code in long mode just fine. It's just a different GDT entry like 32 bit code is. Windows didn't cut 16 but mode because of the processor ut because they took the opportunity to increase the max HANDLE table size greater than 16 bit code can address.
- messe 4y ago
  Just want to point out that not all 16-bit code can run unhindered in long mode. You can run 16-bit protected mode code. But long mode dropped the V8086 mode that made easily emulating 16-bit real mode possible.
  - AshamedCaptain 4y ago
    But you can switch in and out of long mode, so it is also possible to basically do whatever you want. And you also have hardware virtualization. It is a political decision to drop compatibility for 16 bit Windows and DOS (i.e. it was too much programming effort), don't blame the hardware.
mmis1000 4y ago
https://www.joelonsoftware.com/2000/05/24/strategy-letter-ii-chicken-and-egg-problems/ https://www.joelonsoftware.com/2000/05/24/strategy-letter-ii... I think this is the price they are(were?) willing to take. If they don't take backward compatibility seriously. Windows won't exist now at first place.