Let’s make a Computer
… at least the CPU …
Pentium 4
Ultra Sparc 1
Pentium 3
Opteron
Itanium 2 McKinley
CBP 2004-5
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Comp 1017 Digital Technologies
1
Pentium
Data Cache
Code Cache
Instruction
Fetch
Instruction
Decode
Execution
Unit
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Minimalist Computer
What do we need to build a
computer ?
ALU (Arithmetic Logic Unit) “Execution Unit”
(Intel)
Memory
Input Output
A good Name
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Arithmetic Logic Unit
ALU
Input A
Integer Execution Unit
Input B
3
add
2
5
3
sub
2
1
Output
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Comp 1017 Digital Technologies
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Multimedia MMX
ALU
Input A
Input B
ALU
Output
CBP 2004-5
MMX instructions add
bits of images together!
Useful for multimedia
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Processing Idea Nr. 1
Move data in and out of data memory
1.Move data from memory
3
2. add
2
5
0
3
1
2
2
3
5
Memory
DRAM, Hard Disk ..
4
3. Move data into memory
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Processing Idea Nr.2
Move instructions into CPU from code memory
Instruction Memory
(Code Memory)
mov 3 in from memory
3
mov 2 in from memory
IP
add the two numbers
add
2
5
0
3
1
2
2
3
mov the result to memory
5
4
Program
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Registers
Registers are high-speed
memory on the CPU chip
Parking places for data on the
move
AX
6
BX
8
AX and BX are used for ALU
operations
0
6
1
8
MAR
4
MAR is memory address
register, here 4. So result,
6+8=14 will go into memory
cell address 4
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8
Program Memory
Let’s consider a spreadsheet
cell which adds two numbers
x + y. This cell and its
instruction is in memory.
But it is REPRESENTED in
different ways
1. Application
mov ax,[x]
mov bx,[y]
add ax, bx
2. High Level
mov [w],ax
Language like ‘C’
w=x+y;
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3. Assembler
Instructions
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Our computer so far …
0
1
Instruction
Memory
Data
Memory
mar
ip
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4
Comp 1017 Digital Technologies
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SAM-2
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Moving data into Registers
For example …
mov ax , [1]
mov bx , [2]
Instruction
Memory
CBP 2004-5
AX
8
BX
7
mar
0
5
1
8
2
7
3
6
4
1
Comp 1017 Digital Technologies
mov ax , [1]
mov bx , [2]
12
Moving data into Memory
For example …
mov [3] , ax
mov [0] , bx
Instruction
Memory
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AX
8
mov [3] , ax
mov [0], bx
BX
7
mar
0
7
5
1
8
2
7
3
8
6
4
1
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Adding Numbers
For example …
Add ax,bx
Instruction
Memory
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AX
BX
8
7
8
7
15
mar
0
5
1
8
2
7
3
6
4
1
Comp 1017 Digital Technologies
add ax , bx
… this means ‘
add ax to bx,
put the answer
in ax’
14
I’ve never
wrestled with
such a complex
problem before
It must take a lot
of organization
and control !
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Pentium
Organization
and control
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Fetch-Execute Cycle
(Organization and Control)
1. Fetch instruction
from memory
5. Write back results
to registers
ax <- ALU
add ax , bx
4. Do any Memory
Access
2. Decode the instruction
and read any registers
ALU <- ax
ALU <- bx
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(Data cache)
None needed
3. Do any ALU operations
ax + bx
(execute units)
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Fetch-Exec : State 1
Instruction Fetch
add ax , bx
add ax bx
AX
BX
3
1
add ax,bx
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Comp 1017 Digital Technologies
0
3
1
8
2
7
3
1
4
9
18
Fetch-Exec : State 2
Decode, Register
Operations
add ax , bx
add ax bx
AX
BX
3
1
3
1
add ax,bx
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3
1
8
2
7
3
1
4
9
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Fetch-Exec : State 3
ALU Operation
add ax , bx
add ax bx
AX
BX
add ax,bx
1
3
4
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3
1
8
2
7
3
1
4
9
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Fetch-Exec : State 4
Memory Access
add ax , bx
add ax bx
AX
BX
add ax,bx
1
3
4
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3
1
8
2
7
3
1
4
9
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Fetch-Exec : State 5
Register Write
add ax , bx
add ax bx
BX
add ax,bx
3
1
8
2
7
3
1
4
9
4
1
3
4
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Fetch-Execute Cycle
(Organization and Control)
1. Fetch instruction
from memory
5. Write back results
to registers
Data into ax
mov ax , [1]
4. Do any Memory
Access
2. Decode the instruction
and read any registers
Read memory
at addr ‘1’
Read the ‘1’
3. Do any ALU operations
(execute units) Put ‘1’ into MAR
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Fetch-Exec : State 1
Instruction Fetch
mov ax , [1]
mov ax , [1]
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mov ax
1
Comp 1017 Digital Technologies
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3
1
8
2
7
3
1
4
9
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Fetch-Exec : State 2
Decode, Register
Operations
mov ax , [1]
mov ax , [1]
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mov ax
1
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3
1
8
2
7
3
1
4
9
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Fetch-Exec : State 3
ALU Operation
mov ax , [1]
mov ax , [1]
mov ax
1
1
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3
1
8
2
7
3
1
4
9
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Fetch-Exec : State 4
Memory Access
mov ax , [1]
mov ax , [1]
mov ax
1
8
1
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Comp 1017 Digital Technologies
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3
1
8
2
7
3
1
4
9
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Fetch-Exec : State 5
Register Write
mov ax , [1]
mov ax , [1]
mov ax
1
8
8
1
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Comp 1017 Digital Technologies
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3
1
8
2
7
3
1
4
9
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Pentium
1.
Fetch
2.
Decode
3.
ALU
4.
Mem Ops
5.
Reg Write
1
2
3
4
5
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The first microprocessor
A dedicated
design ...
Keypad
Lots of
Electronics
LCD Display
... or a reusable design
Code
Memory
LCD Display
Keypad
Programmable
Electronics
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