8080 Trainer - more info

From: Captain Napalm <spc_at_armigeron.com>
Date: Wed Apr 22 18:02:58 1998

It was thus said that the Great Tony Duell once stated:
>
> > But oddly enough, if you look at the 8080 instruction set through octal
> > eyes, it makes sense. Heck, the 8086 instruction set as see through octal
>
> I'd not thought of it before, but you're right.. Things like the
> register-register MOV instruction are easy in octal...

  It did surprise me when I first realized it. I even made up opcode maps
(2D tables with all the opcodes mapped into the appropriate place) using
four 8x8 tables and it's a lot cleaner than the single 16x16 table I made.
I forgot where I got the idea to view the 8086 code through octal, but I
think I may have gotten the idea from a book on the 8080 or Z80.

> > > Did any machine languages ever write the opcodes like that, I wonder?
> >
> > No, but for some machines it would make sense (say, for the 68k, where
> > most instuctions follow a 4:3:3:3:3 format)
>
> Now that wouldn't look too bad in octal, would it ?

  For most of the instructions it wouldn't be bad. But for the branch
instructions it would be (which are 4:4:8 format).

  -spc (More used to hex than octal though ... )
Received on Wed Apr 22 1998 - 18:02:58 BST