Tag Archives: 7400

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The 6502 ALU in 7400 Logic

After investigating the 6502, Jeremy and I discovered that this ancient processor was still a complex beast of a machine with lots of constituent components and some quirky ways of implementing some features (like the extensive use of gated registers on the output of each combination logic block). The complexity of the 6502’s ALU means that implementing it entirely in large relays is unrealistic. It would be large, costly and the power requirements would be immense.

7400 logic NAND

7400 logic NAND

Instead, we have decided to do what many other 6502 replica makers have done and construct the processor in 7400 logic first.  Continue reading