1. Computer Architecture
Topic 4: Computers
Computer Architecture

2. The Basic Computer Model
Computers can do different things based on what they were made for
Calculators calculate values
Tills record and calculate money totals
However, computers have evolved over time
Originally just for number crunching
Now can do lots of different things
We’re going to look at what a computer is, what a computer can do, and what a computer contains
Computers: Compter Architecture

3. The Basic Computer Model
Before going in-depth with these, we need to know one thing
Different ‘computers’ can do different things
There’s a simple way to break this down
The Input-Process-Output model
Input
Process
Output
Computers: Compter Architecture

4. The Basic Computer Model
Shows the general flow of data through a computer
We give the computer some input
The computer performs a process (or series of processes)
The computer outputs some data
The Input/Process/Output are different per device
Input
Process
Output
Computers: Compter Architecture

5. The Basic Computer Model
Calculator
Calculator receives operands/operator
Calculator performs operations
Calculator displays result
Printer
Printer receives a document
Printer stores document for printing
Printer prints the document
Elevator
Elevator button is pressed
The elevator moves to the correct floor
The elevator door opens in front of user
Computers: Compter Architecture

6. Computers: Compter Architecture
Other Computer Models
There are other computer models out there
Mostly involving programs and how they operate
Some examples include
Sequential model: when instructions in a program are executed one after the other
Parallel model: when instructions in a program are executed simultaneously across multiple processors
Multi-agent model: when multiple computer systems co- operate with each other to achieve a goal
Computers: Compter Architecture

7. Computers: Compter Architecture
Computer Components
Central Processing Unit (CPU, a.k.a. Processor)
Considered to be the brain of the computer
Is a single, small chip (that can be quite fragile)
Responsible for executing programs, performing basic operations, and supervising other components
Computers: Compter Architecture

8. Computers: Compter Architecture
Computer Components
Main Memory (RAM, ROM, EEPROM)
Stores temporary/permanent data
Values for a program
Machine code that will be executed on the CPU
Accessed via addresses (binary numbers determined by CPU architecture)
Comes in different types, chip sizes (both memory and physical size), and different speeds
Computers: Compter Architecture

9. Computers: Compter Architecture
Computer Components
Main Memory (RAM, ROM, EEPROM)
RAM – Random Access Memory
Writable and readable stores for data
But volatile
RAM addresses are temporary, and only store data while the computer is powered on
Computers: Compter Architecture

10. Computers: Compter Architecture
Computer Components
Main Memory (RAM, ROM, EEPROM)
RAM can be found in a few places
‘Sticks’ of RAM for general data storage
CPU can have a cache as well
Caches are fast-access RAM stores used mostly by the CPU
Allows the CPU to store frequently references data (like program instructions)
Can speed up process time over storing this data in usual RAM
Computers: Compter Architecture

11. Computers: Compter Architecture
Computer Components
Main Memory (RAM, ROM, EEPROM)
RAM is great, but sometimes we may not have enough
The computer can compensate for this with virtual memory
Uses sections of slower memory (like EEPROM or Hard Disks) as a replacement for RAM
Is slower (as RAM isn’t entirely used), but used as a ‘last resort’
Computers: Compter Architecture

12. Computers: Compter Architecture
Computer Components
Main Memory (RAM, ROM, EEPROM)
ROM – Read Only Memory
Readable only
Contains pre-made data/programs
Often used to store a program that boots the operating system on the computer
Computers: Compter Architecture

13. Computers: Compter Architecture
Computer Components
Main Memory (RAM, ROM, EEPROM)
EEPROM – Electrically Erasable Programmable Read Only Memory
Writable and readable, and non-volatile
Data is permanently stored until overwritten or destroyed
Comes in lots of different formats
Examples include USB sticks, SD cards, and Solid- State Drives
Computers: Compter Architecture

14. Computers: Compter Architecture
Computer Components
Secondary Storage (Hard-Disk Drives and Solid-State Drives)
Used to store permanent data on the computer
The operating system
Installed programs
Day-to-day files
Slower at being accessed than Main Memory
Examples include
Hard-Disk Drives
Solid-State Drives
Computers: Compter Architecture

15. Computers: Compter Architecture
Computer Components
Input/Output Devices
Help the user use a computer
Input devices let the user interact with the computer
Mouse and Keyboard
Microphone
Output devices let the computer show results/data to the user
Monitor
Speakers
Computers: Compter Architecture