[Python-Dev] %b format? - 8088 like a PDP-11 I think not...

Jack Jansen jack@oratrix.nl
Wed, 06 Jun 2001 13:24:32 +0200

The early microcomputers (8008, 6800, 6502) are actually a lot more like the 
PDP-8 than the PDP-11: a single (or possibly double) accumulator register and 
a few special purpose registers hardwired to various instructions.

The 68000, Z8000 and NS16032 were the first true successors of the PDP-11, 
sharing (to an extent) the unique characteristics of it's design with general 
purpose registers (with even SP and PC being general purpose registers with 
only very little magic attached to them) and an orthogonal design. The 68000 
still had lots of little quirks in the instruction set, the latter two 
actually improved on the PDP-11 set (where a couple of instructions like XOR 
would only work with register-destination because it was added to the design 
in a stage where there weren't enough bits left in the instruction space, I 

And the 8086 was just a souped-up 8080/8008: each register had a different 
function, no orthogonality, etc. Intel didn't get it "right" until the 386 
32-bit instruction set (and even there some of the old baggage can still be 
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