70's computers

Noel Chiappa jnc at mercury.lcs.mit.edu
Wed Oct 24 05:50:30 CDT 2018


    > 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


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