TCS said:
No they weren't. They were hardwired via logic.
This is simply not accurate. Microprocessors typically operate with
instruction and data fetch modes. When an instruction fetch takes place,
the op code causes a branch to an internal memory of the internal cpu state
machine, running on an internal clock. This sets off a process where the
data portion of the instruction or subsequent fetches or registers are used
to manipulate data, or they set some status within the cpu state machine
There is no simple hardwired logic, there is a stored program, a
"microprogram" within the cpu that will "crack" the instruction like a
walnut and see whats inside and eat it if its fresh.
Microinstructions can be 100 bits wide, or for an 8-bit? I dont recall maybe
something like 43 bits wide, it depends.
When there is a micro engine, using micro instructions, stored in microcode
memory, its a micro processor. There is a clock, internal microcode address
generator, next address logic, mux. Can you name any 8 bit cpu that uses
only hard wired logic??
