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CPU Instruction Cycle/ part2 Lecturer: Noor Kadhum


Example 3 : Sequential instruction
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What is the control sequence for the following instruction?
Add R1, X
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Now:
- The content of R1 is already available in the CPU.
- The content of X is resident in the memory , this mean that the value of X should be brought to CPU (i.e. read it),

Solution:
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1- Pc out ,ARin,Read,Set carry of ALU, Clear y,Add, Zin.

2-Zout, Pcin, WMFC.

3- DRout,IRin .

4- address of IR out, ARin, Read.

5- R1 out, yin, WFMFC.

6- DRout,add,Zin.

7- Zout,R1 in

8- end.

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Exercise 1: What are the write a micro-program for implementing the following instructions?
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1-Add R2, [X].

2- load X

3- move x,R1

4- inc

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Exercise 2: A computer has 4 mathmatical operation only(add, sub, mul, div). how to execute the instruction (CMP X,R1) on such computer?write the control sequence for execute cycle for this instructin.