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Article #625586Re: PDP 11/40 system manual
From: Peter Flass
Date: Sun, 12 Aug 2018 11:20
Date: Sun, 12 Aug 2018 11:20
20 lines
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2651 bytes
Dan Espen <dan1...@gmail.com> wrote: > I've done huge amounts of assembly programming and the instructions > get the job done. Issues with the base registers are easy to deal with > once you figure out that each subroutine should have it's own base > register, don't attempt to make all code addressible at once. > My copy of Pugh is packed, but I think this was the intention. 4K can be a bit small for a subroutine, but I think the designers expected programmers to divide their programs into smallish subroutines. I don't think I've written a lot of programs that needed multiple base registers. On the other hand it's more complicated than it needs to be to save a base register and load a new one - especially if you want to write reentrant code, where the recommended technique requires OS intervention to get a free the savearea. A hardware stack would have helped. and maybe one instruction to push a register and load it with the address of the next instruction. -- Pete
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