Transcript Structured Systems Analysis and Design Methodology

Computer Fundamentals
Northern College Diploma
Philip Bird
Processor Architecture
Virtually every computer that has been
built shares the same common layout.
Von Neumann – programs and data
both exist in the computers memory.
A program written for one type of
computer can be written for any
computer.
Computer Fundamentals
Philip Bird
IAS
Early History
Z3
Zuse
1941
Von Neumann
1952
Manchester Mark1
EDVAC
Williams
Von Neumann
1949 (Oct)
1952
ABC
EDSAC
Atanasoff/Berry
Wilkes
1942 Not working
1949 (May)
LEO
Wilkes
1951
A Computer is a…..Binary/Electronic/Stored Program device
Colossus
Turing
Harvard Mark1 ASCC
1942
Aiken
1943
ENIAC
BINAC
UNIVAC
Base 10
Mauchlay/Eckert
Mauchlay/Eckert
Mauchlay/Eckert
1949 (Sept)
1951
1946
Binary/Electronic/Memory
Mechanical
Hard Wired
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Philip Bird
Central Processing Unit
Control Unit
ALU
Busses are used to carry
the data around the CPU
in byte sized chunks.
Memory
I/O Unit
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Directs the step by step working based
on pulses sent from a clock
The Arithmetic and Logic Unit perform
the calculations using adder circuits. It
also contains flags that monitor the
result of those calculations. (CNZ)
Memory is usually RAM or ROM made
up of many individual cells each storing
1 byte. Both data and the programs are
stored here.
Handles communication with
peripherals such as the keyboard.
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Central Processing Unit
Program Counter
+1
Instruction Register
Accumulator
Flags
Memory Address Register
Memory Data Register
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0
4
8
1
5
9
2
6
10
3
7
11
Philip Bird
Fetch Execute Cycle
Repeat
MAR=PC
PC
10
PC=PC+1
+1
MDR=Memory[MAR]
IR
ACC
IR=MDR
LOD 5
Execute IR
17
Until halt
000
MAR
MDR
05
LOD
17 5
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0
LOD 5
4
1
HLT
5
8
17
9
2
6
10
3
7
11
Philip Bird
Instructions
Instructions are made up of 2 parts:
Operation code
Operand
0100
0101
Machine code
ADD
5
Assembly Language
Binary values are difficult to work. The assembler converts assembly
language instructions into machine code.
LOD 10
ADD 10
HLT
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0001 1010
Assembler
0100 1010
0000 0000
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Instruction Set
Op Code
Operand
HLT
Meaning
Halt
LOD
5
Load contents of address 5 into Accumulator
STO
5
Store Accumulator in address 5
LDI
5
Load the number 5 into the Accumulator
ADD
5
Add the contents of address 5 to the Accumulator
SUB
5
Subtract the contents of address 5 from the Accumulator
ADI
5
Add 5 to the Accumulator
SBI
5
Subtract 5 from the Accumulator
INC
Increase the Accumulator by 1
DEC
Decrease the Accumulator by 1
JMZ
5
Jump to address 5 if Accumulator is zero
JNZ
5
Jump to address 5 if Accumulator is not zero
JMN
5
Jump to address 5 if Accumulator is minus
JMP
5
Jump to address 5
JCS
5
Jump to address 5 if Carry is set to 1
JCC
5
Jump to address 5 if Carry is set (clear) to 0
Computer Fundamentals
Philip Bird
Summary
What is the Von Neumann architecture?
What is the Fetch/Execute cycle?
Use SCAry to try the example assembly
programs.
Computer Fundamentals
Philip Bird