Computer Organization Lecture 18

1. Computer OrganizationLecture 18 IF, ID, R-type microprogramming Exam 2 review University of Portland School of Engineering

2. Microprogramming overview • Review instructions, understand goals • Determine state diagram • Microprogram individual instructions • List tokens on one line • Repeat for remaining clocks • Merge all instructions • Test, test, test University of Portland School of Engineering

3. MicroAsm • Java application: MicroAsm.class, SavitchIn.class • Microinstruction: free format, no fixed fields • Requires input file: text-only, file.upg • Creates output file: file.txt • Errors: command line file name,file I/O, unrecognizable token • Execution: BlueJ or DOS command line University of Portland School of Engineering

4. MicroAsm syntax • Directives org: nbr Sets uPC to value of nbr, used with branch token // comment Everthing after // ignored • Each line • directives (optional) • tokens (signals to assert) • last line contains return University of Portland School of Engineering

5. MicroAsm source format University of Portland School of Engineering

6. uProgram tokens University of Portland School of Engineering

7. uProgram tokens, continued. University of Portland School of Engineering

8. uProgram tokens, continued. University of Portland School of Engineering

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11. A B Reset Lw or Sw R-fmt C Beq Jump G I J Sw Lw D F H E Partial MDP16 state diagram University of Portland School of Engineering

12. ID IF Reset 2 clocks sll srl lw sw R-fmt nop 1- 3 additional clocks j beq addi subi andi ori MDP16 state diagram University of Portland School of Engineering

13. IF state ? • Write instruction from memory into IR • Increment the program counter IRwr PCinc University of Portland School of Engineering

14. ID state ? • Determine optimistic branch address • Branch to opcode Alua-pc Alub-ext imm aluopadd branch University of Portland School of Engineering

15. R-type instruction • Op code: 01 • Func bits (IR[3:0]) determine ALU operation • Write result into register file University of Portland School of Engineering

16. R-type EX state? • Origin: 0x10 • Operation: clock 3 • RALUout = A funct B • Functional units • ALU funct = IR[0:3] • ALU inputs • R0 • R1 Org: 10 alua-r0 Alub-r1 University of Portland School of Engineering

17. R-type WB state? • Next: return to IF • Operation: clock 4 • Reg [ IR(9)] = ALUout • Functional units • Must write to reg file • Data comes from RALU • Use IR[9] as destination register rwr reg-ralu return University of Portland School of Engineering

18. Exam 2 review See website Syllabus & Reference page University of Portland School of Engineering

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20. IF state ? • Write instruction from memory into IR • Increment the program counter IRWr PCinc University of Portland School of Engineering

21. ID state ? • Determine optimistic branch address • Dispatch to opcode Imm aluA_Pc aluB_Ext aluOpAdd branch University of Portland School of Engineering

22. IF, ID microprogram Two microinstructions, two ROM contents University of Portland School of Engineering

23. R-type microprogram • Func bits (IR[3:0]) determine ALU operation • Write result into register file Rwr reg_Ralu Return aluA_R0 aluB_R1 University of Portland School of Engineering

24. R-type microprogram University of Portland School of Engineering