Comp 1017 Digital Technologies 1CBP 2013-14

Let’s make a Computer

Comp 1017 Digital Technologies 2CBP 2013-14

Let’s make a CPU

CBP 2004-5 Comp 1017 Digital Technologies 3

Pentium

CBP 2004-5 Comp 1017 Digital Technologies 4

Arithmetic Logic Unit

Input A Input B

Output

ALU Integer Execution Unit

5

3 2add 1

3 2sub

CBP 2004-5 Comp 1017 Digital Technologies 5

Input A Input B

Output

ALU

ALU

Multimedia MMX

CBP 2004-5 Comp 1017 Digital Technologies 6

5

3 2add

0

1

2

3

4

3

2

5

Processing Idea Nr. 1

Move data from memory

Move data into memory3.

2.

1.

Data Memory

Move data in and out of data memory

CBP 2004-5 Comp 1017 Digital Technologies 7

5

3 2add

0

1

2

3

4

3

2

5

Processing Idea Nr.2

IP

(Code Memory)

mov 3 in from memorymov 2 in from memoryadd the two numbersmov the result to memory

Instruction Memory

Program

Move instructions into CPU from code memory

CBP 2004-5 Comp 1017 Digital Technologies 8

Registers-1

0

1

4

6 8

6

8

AX BX

CBP 2004-5 Comp 1017 Digital Technologies 9

Registers-2

0

1

4

6 8

6

8

4

AX BX

MAR

CBP 2004-5 Comp 1017 Digital Technologies 10

ip

Data Memory

Instruction

Memory

0

1

4mar

Our CPU so far …

CBP 2004-5 Comp 1017 Digital Technologies 11

SAM-2

CBP 2004-5 Comp 1017 Digital Technologies 12

Hierarchy of Programming

2. Written in HLL (C)

3. CPU executes machine code

mov ax,[x]mov bx,[y]add ax, bxmov [w],axw = x + y ;

1. Application

CBP 2004-5 Comp 1017 Digital Technologies 13

Moving data into Registers

Instruction Memory

0

1

2

mar 3

4

mov ax , [1]

85

8

76

1

BXAXmov ax , [1] mov bx , [2]mov bx , [2] 7

For example …

Comp 1017 Digital Technologies 14CBP 2004-5

Moving data into Memory

Instruction Memory

0

1

2

mar 3

4

mov [3] , ax

85

8

76

1

BXAXmov [3] , axmov [0], bx

mov [0] , bx 7

For example …

8

7

Comp 1017 Digital Technologies 15CBP 2004-5

Adding Numbers

Instruction Memory

0

1

2

mar 3

4

add ax , bx

85

76

1

BXAXAdd ax,bx

7

For example …

8

8 715

Comp 1017 Digital Technologies 16CBP 2004-5

I’ve never wrestled with

such a complex

problem beforeIt must take a lot of organization and control !

CBP 2004-5 Comp 1017 Digital Technologies 17

Pentium

Organization and control

CBP 2004-5 Comp 1017 Digital Technologies 18

Fetch-Execute Cycle

1. Fetch instruction from memory

2. Decode the instruction and read any registers

3. Do any ALU operations (execute units)

5. Write back results to registers

add ax , bx

4. Do any Memory Access

ALU <- ax ALU <- bx

ax + bx

(Data cache)

ax <- ALU

None needed

CBP 2004-5 Comp 1017 Digital Technologies 19

add ax , bx

add ax,bx

add ax

0

1

4

3

2

bx

Fetch-Exec : State 1Instruction Fetch

8

3

7

1

9

3 1

AX BX

CBP 2004-5 Comp 1017 Digital Technologies 20

0

1

4

3

2

Fetch-Exec : State 2Decode, Register Operations

8

3

7

1

9

add ax , bx

add ax,bx

add ax bx

3 1

3 1

AX BX

CBP 2004-5 Comp 1017 Digital Technologies 21

0

1

4

3

2

Fetch-Exec : State 3ALU Operation

8

3

7

1

9

add ax , bx

add ax,bx

add ax bxAX BX

3 14

CBP 2004-5 Comp 1017 Digital Technologies 22

0

1

4

3

2

Fetch-Exec : State 4Memory Access

8

3

7

1

9

add ax , bx

add ax,bx

add ax bxAX BX

3 14

CBP 2004-5 Comp 1017 Digital Technologies 23

0

1

4

3

2

Fetch-Exec : State 5Register Write

8

3

7

1

9

add ax , bx

add ax,bx

add ax bxBX

3 14

4

CBP 2004-5 Comp 1017 Digital Technologies 24

Fetch-Execute Cycle

1. Fetch instruction from memory

2. Decode the instruction and read any registers

3. Do any ALU operations (execute units)

5. Write back results to registers

(Organization and Control)

mov ax , [1]

4. Do any Memory Access

Read the ‘1’

Put ‘1’ into MAR

Data into ax

Read memory at addr ‘1’

CBP 2004-5 Comp 1017 Digital Technologies 25

mov ax , [1]

mov ax , [1]mov ax

0

1

4

3

2

1

Fetch-Exec : State 1Instruction Fetch

8

3

7

1

9

CBP 2004-5 Comp 1017 Digital Technologies 26

mov ax , [1]

mov ax , [1]mov ax

0

1

4

3

2

1

Fetch-Exec : State 2Decode, Register Operations

8

3

7

1

9

CBP 2004-5 Comp 1017 Digital Technologies 27

mov ax , [1]

mov ax , [1]mov ax

0

1

4

3

2

1

Fetch-Exec : State 3ALU Operation

1

8

3

7

1

9

CBP 2004-5 Comp 1017 Digital Technologies 28

mov ax , [1]

mov ax , [1]mov ax

0

1

4

3

2

1

Fetch-Exec : State 4Memory Access

1

8

3

7

1

9

8

Comp 1017 Digital Technologies 29CBP 2004-5

mov ax , [1]

mov ax , [1]mov ax

0

1

4

3

2

1

Fetch-Exec : State 5Register Write

1

8

3

7

1

9

88

CBP 2004-5 Comp 1017 Digital Technologies 30

Pentium

5

12

3

4

1. Fetch2. Decode3. ALU4. Mem Ops5. Reg Write