A-Level Computing
computer hardware & architecture
Introduction.
• Learn about the internal structure of the
computer
• The elements which make up a computer
system
• How these elements work together
Hardware & Software.
• Hardware:
‣ The physical components of a computer
‣ Things you can actually touch
• Software:
‣ The programs (set of instructions which
run on the hardware)
‣ Don’t physically exist
Hardware: Computer.
MAIN MEMORY
INPUT
DEVICES
PROCESSOR
AUXILIARY
STORAGE
OUTPUT
DEVICES
Hardware: Computer.
• All computer systems follow a basic structure
• No mater the size or type
• All feature Processor, memory, input and
output devices
The processor.
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•
•
•
•
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The brain of the computer
Fetches, decodes and executes instructions
Is found on a chip, which features millions of
components
1cm in size
Integrated with main
memory
Since the 1960s chips
have grown in size and
performance hugely
Main Memory.
• Holds the program and data currently being
used by the computer
• Millions of small storage units – bytes
• Each has own address
• One byte holds one small piece of
information
• The total number of bytes is the computer’s
memory size
Main Memory.
• 1024 bytes = 1kb (kilobyte)
• 1024kb = 1mb (megabyte)
• 1024mb = 1gb (gigabyte)
• 1024gb = 1tb (terabyte)
• 1024tb = 1pb (petabyte)
Main Memory.
• Like processors, memory has increased
hugely in the last 20 years.
• 1980 - 32kb of memory
• 2010 - 2gb of memory standard
• “640kb of memory is the limit - more
than anyone will EVER need!”
bill gates, 1981
Types of Memory.
• RAM – Random Access Memory
• Volatile – loses contents when power
turned off
• ROM – Read Only Memory
• Non-volatile – doesn’t get lost
• Holds programs and instructions to start
computer/operating system
Cache Memory.
• Super fast section of memory
• Very small amounts
• Holds frequently used instructions so
they can be accessed very quickly over
and over again.
• Sizes range from 100kb to almost 1mb
Storage.
• Disk storage
• Capacity measured in bytes
• Much larger than main memory – 100s
of Gigabytes on modern pc’s
• Holds software
• Long Term storage
Input & Output.
• How computer can accept data and
instructions
• Output devices are how computer can
give information ‘out’
Inside a computer.
• At the heart of every computer is the
CPU (Central Processing Unit)
• It refers to that part of the processor
which 'processes' the data and
instructions.
Inside a computer.
ALU
Control Unit
Register
Inside a computer.
• ALU (Arithmetic and Logic Unit) which
performs the calculations on the data.
• The Control Unit - which controls all
operations inside the computer.
• Some Memory storage. A register is a
place where a single item of data can
be stored.
Inside a computer.
• All computers will have at least one
•
input device (eg keyboard, mouse),
and at least one output device (eg
monitor).
All computers have some memory.
The program a computer is running as
well as the data are all stored in
memory.
Inside a computer.
• All computers will have at least one
•
input device (eg keyboard, mouse),
and at least one output device (eg
monitor).
All computers have some memory.
The program a computer is running as
well as the data are all stored in
memory.
Inside a computer.
ALU
Input
Device
Control
Unit
RAM
Register
Output
Device
Buses.
• A set of parallel wires connecting
components of a computer.
• Three separate buses in the CPU
• Control Bus
• Address Bus
• Data Bus
Inside a computer.
ALU
Input
Device
Control
Unit
Register
RAM
Data | Address | Control
Output
Device