Re:What is the PDP-11 instruction set?
by mikequinlan on Monday October 19, 2020 @10:06AM
(#24826469)
I am curious, do you know if user-mode programs had access to more than a single 256K word address space? Did they add something like segment registers or a split between Data and Instruction space?
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The answer is yes they did. I think the PC was extended and you switched explicitly between segments via a small set of instructions, so code/data can't span segments. I think of it as being like an overlay system without actually overlaying.