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From: Thomas Koenig <tkoenig@netcologne.de>
Newsgroups: comp.arch
Subject: Re: The Design of Design
Date: Sat, 27 Apr 2024 11:18:47 -0000 (UTC)
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John Levine <johnl@taugh.com> schrieb:

[PDP-10]

> I misread the manual. The extended addresses were 30 bits or about 4GB
> which was plenty for that era, but the way they did it in 256K word
> sections was still a kludge. In the original PDP-6/10 every
> instruction could address all of memory. In extended mode you could
> directly address only the current section, and everything else needed
> an index register or an indirect address. 
>
> While this wasn't terribly hard, it did mean that any time you wanted
> to change a program to run in extended mode you had to look at all the
> code and check every instruction that did an address calculation,
> which was tedious.

Hmm... would a simple recompilation have done the trick, or were there
also issues with integers being restricted to 18 bits, for example?