1 Chapter 5. Control Design 2 (No Transcript) 3 Two approaches
for control unit design A hard-wired control unit a sequential
logic circuit to generate specific fixed sequences of control
signals change in behavior only by redesign. A microprogrammed
control unit by organizing control signals into
microinstructions. The signals are implemented by a kind of
software(or firmware) rather than hardware. design change change
the contents of control memory. emulation a microprogrammed CPU
can execute programs written in the machine language of other
computers. Slower due to fetch. more costly due to the presence
of the control memory and its 5 5.1.2. Hardwired Control design
method 1 The classical method of sequential circuit design. For
a P-state circuit log2P flip-flops are required. design method 2
One-hot method one flip-flop per state. Expensive in terms of
F/F but simplify CU design and debugging. 6 (No Transcript) 7
(No Transcript) 8 (No Transcript) 9 Classical method S0 00 S1 01
S2 10 and S3 11 10 (No Trans