By: Heikki Kultala (heikki.kultala.delete@this.gmail.com), August 12, 2022 11:10 pm
Room: Moderated Discussions
none (none.delete@this.none.com) on August 12, 2022 3:53 am wrote:
> Megol (golem960.delete@this.gmail.com) on August 12, 2022 3:04 am wrote:
> [...]
> > > Ugly, but not so ugly as x86.
> > Debatable. X86 is like two separate architectures with some similarities,
> > the 8086-80286 was pretty clean, the 80386 too.
>
> I guess you are talking about encoding which was cleaner than 68k IIRC. Because for the rest,
> what was not ugly in 8086? Non orthogonal use of registers all around the place, non
> orthogonal settings of flags, segments, etc.
Non-orthogonal use of registers is practical, as it allows denser instruction encoding and also (before PRF-based register renaming) mat also have allowed simpler datapath. Calling it "ugly" is just irrelevant and shows wrong priorities.
> Megol (golem960.delete@this.gmail.com) on August 12, 2022 3:04 am wrote:
> [...]
> > > Ugly, but not so ugly as x86.
> > Debatable. X86 is like two separate architectures with some similarities,
> > the 8086-80286 was pretty clean, the 80386 too.
>
> I guess you are talking about encoding which was cleaner than 68k IIRC. Because for the rest,
> what was not ugly in 8086? Non orthogonal use of registers all around the place, non
> orthogonal settings of flags, segments, etc.
Non-orthogonal use of registers is practical, as it allows denser instruction encoding and also (before PRF-based register renaming) mat also have allowed simpler datapath. Calling it "ugly" is just irrelevant and shows wrong priorities.
