Anon (no.delete@this.spam.com) on August 11, 2022 5:45 pm wrote:
> Brett (ggtgp.delete@this.yahoo.com) on August 11, 2022 3:26 pm wrote:
> > Anon (no.delete@this.spam.com) on August 11, 2022 11:43 am wrote:
> > > Megol (golem960.delete@this.gmail.com) on August 11, 2022 9:25 am wrote:
> > > > Have you actually looked at the 68080 design? The extensions aren't that clean, and for a good reason:
> > > > there isn't encoding space without adding prefixes or adding a partially incompatible mode.
> > >
> > > Where did you find the instruction format?
> >
> > Any 68k manual, each instruction spells out the bits:
> > https://web.njit.edu/~rosensta/classes/architecture/252software/code.pdf
> >
> > There is unused state in the mode bits that can be used to add another 8 data registers transparently for
> > one source. Though instead the AMMX extension added 32 bit instructions and used a similar format.
> >
> > https://cdn.discordapp.com/attachments/730698753513750539/843620828612526110/VampireProgrammingGuide.pdf#page55
> >
> > ColdFire obsoleted the 2 of the 3 opmode operation size bits for all but MOVE loads/stores. That frees up
> > huge opportunities for expansion. The plan may have been to use these bits to double the register file.
> >
> > http://bitsavers.org/components/motorola/Coldfire/1995_Coldfire_Family_Programmers_Reference.pdf
> >
> > Ugly, but not so ugly as x86.
>
> Thanks for posting links to manuals I already have without answearing my question, but what I really
> want is the actual basic instruction format for the 68080, and how it extended over 68060.
>

Starting on page 55, look around page 80 on the second link above.
All bits explained.