Thursday, April 5, 2007

How your computer works, dumbed down ver

Believe it or not, a fully functional MIPS processor could run off of these pieces only. Perhaps not very efficiently, but... Note: this is a mapping of how the actual hardware works! Pic 1: ALU operation. That's a basic arithmetic computation, including reading instruction, value, the computation, and writing back to the register.

Pic 2: load/store. Read instruction, address values, compute effective memory address, and read or write. Load data value in result register.

Pic 3: This is where it get a little complicated. We want to be able to make decisions, ie branch in our code if a certain condition is met. Compute condition, test if eq to zero, and if so then jump to new code, ie load appropriate code address into the program counter. Believe it or not, these three combinations of hardware can do anything your computer can do, except input/output. Amazing, eh?

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