24 Oct
2018
24 Oct
'18
3:50 a.m.
From: Paul Koning
Some years ago I learned the architecture of the Dutch
Electrologica X1
and X8 machines. ... they gain a lot of efficiency by allowing almost
all instructions to optionally set a condition flag, and almost all
instructions to be executed conditionally on that flag. So a lot of
code full of branches becomes much shorter. ... For example:
if (x >= 0) { foo (); x += 2; }
else x -= 3;
translates to just 5 instructions:
Very clever!
What's the word length on that machine, BTW? I ask because it would be hard
to pull that trick on most short-word-length machines, there just isn't a
spare bit or two in the instruction to add that.
Noel