computer organization lecture 18

Fall 2006

Lillevik 333f06-l18 1University of Portland School of Engineering

EE 333

Computer OrganizationLecture 18

IF, ID, R-type microprogrammingExam 2 review

Fall 2006


EE 333

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

Fall 2006


EE 333

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

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EE 333

MicroAsm syntax• Directives

org: nbrSets uPC to value of nbr, used with branch token

// commentEverthing after // ignored

• Each line – directives (optional)– tokens (signals to assert)– last line contains return

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MicroAsm source format

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uProgram tokens

Token Value FunctionBranch 0000 0100 Branch the uPgm to the opcode (default is next address)

Rwr 0000 0400 Write to the REG file

Imm 0000 0800 uPgm controls ALU function (default is IR[3:0])

PCinc 0000 1000 Increment the PC

PCwr 0000 2000 Write to the PC

PCwrcond 0000 4000 Write to the PC if EQ is asserted

EPC 0000 8000 Select EPC for PC write

IoD 0001 0000 Select RALU for memory address (default is PC)

MEMwr 0002 0000 Write to the memory (default is to read)

IRwr 0004 0000 Write to the IR

MDRwr 0008 0000 Write to the MDR

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uProgram tokens, continued.

Token Value Function SPCwr 0010 0000 Write to SPC register

PCsrc 0020 0000 PC write data is branch address (default is jump address)

ALUa-R0

ALUa-PC

0040 0000

0000 0000

First ALU argument is R0

First ALU argument is PC (default is PC)

ALUb-R1

ALUb-Ext

ALUb-Trnc

0000 0000

0080 0000

0100 0000

Second ALU argument is R1

Second ALU argument is Sign Extended offset

Second ALU argument is Truncated offset

REG-RALU

REG-MDR

0000 0000

0200 0000

REG write data is the RALU

REG write data is the MDR

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uProgram tokens, continued.

Token Value Function REGfmt 0800 0000 Selects IR[10] for the REG destination (default is IR[9])

ALUOpadd

ALUOpsub

ALUOpand

ALUOpor

ALUOpsll

ALUOpsrl

0000 0000

1000 0000

2000 0000

3000 0000

8000 0000

9000 0000

ALU function is add

ALU function is subtract

ALU function is logical AND

ALU function is logical OR

ALU function is shift left logically

ALU function is shift right logically

Next

Return

uPC+1

00

Inserts uPC+1 into uPgm next address (default)

Inserts 00 into uPgm next address

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EE 333

Fall 2006


EE 333

Partial MDP16 state diagram

A

G

C

D

E

F

H

B

JI

Lw or SwR-fmt Beq Jump

Reset

Lw Sw

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EE 333

MDP16 state diagram

ID

sllno

p

R-fmt

sw

srl lw

addi

beq j ori

subi

andi

IFReset

1- 3

add

itio

nal c

lock

s

2 clocks

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IF state ?

• Write instruction from memory into IR

• Increment the program counter

IRwr

PCinc

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ID state ?

• Determine optimistic branch address

• Branch to opcode

Alua-pc

Alub-ext

imm

aluopadd

branch

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R-type instruction

• Op code: 01

• Func bits (IR[3:0]) determine ALU operation

• Write result into register file

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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

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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

Fall 2006


EE 333

Exam 2 review

See website Syllabus & Reference page

Fall 2006


EE 333

Fall 2006


EE 333

IF state ?

• Write instruction from memory into IR

• Increment the program counter

IRWr

PCinc

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ID state ?

• Determine optimistic branch address

• Dispatch to opcode

Imm

aluA_Pc

aluB_Ext

aluOpAdd

branch

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IF, ID microprogram

Two microinstructions, two ROM contents

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EE 333

R-type microprogram

• Func bits (IR[3:0]) determine ALU operation

• Write result into register file

aluA_R0

aluB_R1

Rwr

reg_Ralu

Return

Fall 2006


EE 333

R-type microprogram

computer organization lecture 18

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