7.3 8-bit micro-architecture

Question 1

How is a fetch-decode-execute controller (timing unit) constructued from a counter

Answer 1

The counter increases to values which in turn let the demultiplexor select values

Question 2

What does the data-path in the hex-8 micro-architecture look like

Answer 2

• Data path contains the registers and functional blocks to compute.
• Multiplexers used to select input registers to ALU.
• Wires come from Control to choose operations.
• Result register hidden from ISA — implementation detail.

Question 3

How does the decode phase work in the hex-8 micro-architecture (using de-multiplexors)

Answer 3

Selects instruction based on opcode