25 Sep
2018
25 Sep
'18
2:45 a.m.
On 9/24/2018 4:20 PM, Paul Winalski wrote:
No doubt about it--x86 instruction encoding is
butt-ugly and wasteful,
due to the need for backward compatibility with what was originally an
8-bit architecture. Does SPARC have the vector instructions that have
been added to x86 over the years?
The 8086 was the first of the "x86"
line, which was 16-bit, although
it's I/O was more 8080-ish if I recall correctly. The 8088 was an 8-bit
data bus, granted, but having done both 8080 and 8086+ assembler, you
couldn't really tell the difference, programming-wise between the 8086
and the 8088, 16-bit registers, and all.
Cutting costs, as always, IBM opted for the 8088, which allowed them to
use an 8085-style I/O architecture.
Also, granted, to this day you can still use only 8-bits of a register:
MOV AL,0x80
art k.