FIT1047 Study Guide - Final Guide: Instruction Register, Processor Register, Memory Address
31 May 2018
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Computer Architecture
Computer Architecture
• CPU (Central Processing Units) is the component of a computer that does most of the actual
"computing"."
• CPU is a sequence of very simple instructions. (Unlike Java, Python, C++)
• Formed from simple logic gates (AND, OR, NOT)
• Modern CPU's contains millions of transistors
o Most widely used: ARM & Intel x86
Moore's Law: Number of components per integrated circuit seemed to double every year.
• CPU's only execute machine code
o Programs need to either compiled into machine code or interpreted
• Compiler turns code into a machine code or byte code (does at once) <C++ uses this
• Interpreter interprets line by line <Java uses this
Machine Code
• Low level programming language
• Sequence of individual instructions, each of which is a sequence of bits
• Instructions consist of one or more words
• CPU can only execute machine instruction that is stored in the main memory of the computer
• Each CPU has its own machine code
o A program that can run on an ARM processor will not work on an Intel x86 processor.
• Memory contains both instructions and data, and there is no way of distinguishing the two.
• Machine code is executed step by step
o CPU starts with first instruction, executes it, then moves on to the instruction
immediately following the first one, and so on.
Instruction Set Architecture
• Set of machine code instructions that a particular type of CPU understands is called the
Instruction Set Architecture or ISA.
• ISA's need to
o Do maths (add, subtract, multiply, compare)
o Move data between memory, CPU and I/O devices
o Execute conditionals and loops
• CPU's do not operate directly on memory. They copy small pieces of data into the CPU, then
performs the operations, and then copies them back into the memory.
o For input and output devices, the CPU must be able to transfer data from (ex) the
keyboard or the hard disk into memory, or send data to the network interface.
• Conditional: If the user enters 'A', then do something.
• Loop: Piece of code that is executed multiple times. 'for each character in the text, do the
following: change from lower to upper case'
CPU Components
Memory
• Computers have a certain amount of memory (RAM). Ex 4GB
• Main memory of computer can be thought as a sequence of locations, each of which can store
one value.
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Document Summary
Computer architecture: cpu (central processing units) is the component of a computer that does most of the actual. computing. : cpu is a sequence of very simple instructions. (unlike java, python, c++, modern cpu"s contains millions of transistors. Formed from simple logic gates (and, or, not: most widely used: arm & intel x86. Interpreter interprets line by line
