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Showing posts from May, 2017

Register Design: Program Counter

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It's been a while since my last post ... pretty much 10 months in fact ... and I'd love to say I've been quietly working on my relay computer in the meantime but I haven't. Designing, building and blogging about the various parts of the computer is really time consuming and unfortunately I'm just one of those people who has way too many hobbies. Anyway, after picking up some subscribers on YouTube I thought it was high time (or maybe I felt guilty enough) to focus back on the computer and get it through to the next milestone ... where it can step through a simple program stored in its memory without any human intervention (beyond entering the program itself and setting the computer running).

So where to begin? The three units that'll need building are the program counter, incrementer and memory. To recap: the memory holds the instructions that make up the program to be executed; the program counter points to the current instruction (line of program) in the memo…