Comment by dboreham
16 hours ago
Until I read this I did not know that 1970s microprocessors had register renaming. Feel a little cheated, thinking for all those years that they were actually moving the bits.
16 hours ago
Until I read this I did not know that 1970s microprocessors had register renaming. Feel a little cheated, thinking for all those years that they were actually moving the bits.
If you work through a math problem with pen and paper or nand2tetris or nandgame.com then it becomes obvious that changing indexes into a register file (a.k.a. pointers) are way faster and easier than wires to move stuff around.
How do you think the EXX and EX AF,AF' instructions work on the Z80?
And EX DE, HL
E to the u, du dx, E to the x, dx!
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If you feel cheated now, wait until you find out that the ALU in the 8-bit Z80 was just 4 bits. :-)
Does this have any similarities at all to the fact that the Pentium 4 used a 16-bit ALU?