4 Computer Systems Flashcards
What are Some types of hardware?
Input/Output devices
Secondary Storage
Primary Storage
Processors
What do input/output devices do?
I/O devices allow users to input data into the computer, or receive a data output from the computer. E.g. Keyboard Mouse Monitor Speakers
What is secondary storage?
Secondary storage is the memory in which the computer can store the data or instructions which are NOT currently in use.
Not all computer systems use secondary storage.
E.g.
Hard Disk Drive (HDD)
Solid State Drive (SSD)
Compact Disk (CD)
Flash (USB Drive)
What is Primary storage?
Primary storage is the memory in which the computer can store the data or instructions that are currently in use.
The two main types of primary storage are:
Random Access Memory (RAM)
Read-Only Memory (ROM)
What are processors?
A processor is a special component that processes data and instructions to control other components within the computer.
The two main types of processor are:
Central Processing Unit (CPU).
Graphics Processing Unit (GPU).
What are two types of computer systems?
General Purpose systems
Embedded systems
What are General Purpose systems?
General purpose systems are capable of performing many different tasks. E.g. PCs Macs Smartphones
What are embedded systems?
An embedded system is a computer system which is built into another device to support its operation. E.g. Washing machines Cameras Printers
What are transistors?
Transistors are electrical components made from semiconductor materials that can act as electrically-controlled switches.
Transistors can be used to temporarily store data, for example in some forms of primary storage (memory).
Why do we use binary form?
Underneath the surface, computers are electrical devices that process information by controlling the flow of electricity through billions of wires and transistors (electrical switches) inside the central processing unit and other components.
The presence of electricity represents a 1, and an absence of electricity represents a 0.
What are the transistors in the CPU used for?
Inside a Central Processing Unit (CPU), transistors are arranged into circuits to perform operations such as calculations when electricity is passed through them.
For example, transistors can be arranged to form an ‘adder’ circuit that can accept two binary numbers, and output the sum of their values.
Modern CPUs contain over 3 billion transistors, allowing them to perform billions of calculations per second.
What are logic gates?
Logic gates are when multiple transistors are are arranged together to form more complex switches that only allow electricity to flow if all or some of the transistors are on
What are some examples of logic gates?
The AND gate performs the Boolean AND function:
It will only output true if both of its inputs are true.
The OR gate performs the Boolean OR function:
It will output true if either or both of its inputs are true.
The NOT gate performs the Boolean NOT function:
It takes one input and inverts it.
What are logic circuits?
Logic gates can be combined to create complex logic circuits
These logic circuits can perform functions such as adding numbers and storing data
How do you evaluate Boolean expressions?
To evaluate a Boolean expression, you should substitute all of the values in for the variables and then use the definitions of the different Boolean functions to simplify it one step at a time.`
What is the order you should evaluate a Boolean expression?
You should evaluate any expression in brackets first, for example:
NOT(True OR False)
NOT(True)
False
What are truth tables?
Truth tables are another method of evaluating expressions
A truth table shows every possible combination of inputs and the resulting output
The truth table shows the input and output state for each combination
The table can then be used to look up the output.
What is the most common type of computer software?
Application software
What is the purpose of application software?
Application software helps a user of a computer system to complete a given task.
What are some examples of application software?
Presentation software
Word processors
Web browsers
What is the purpose of system software?
System software controls the hardware of the computer and provides an environment for applications to run
What are Operating systems?
Operating systems (OSs) are one type of system software. OSs manage access to the hardware in the computer.
What are device drivers?
Device drivers are one type of system software
Device drivers are small programs which tell the operating system how to use a piece of hardware
What is Utility software?
Utility software is one type of system software
Utility software performs maintenance tasks to make sure the operation of the system continues
What is utility software?
Utility software is a subset of system software. Utility software programs perform specific tasks to help maintain the system
What are the 4 main types of utility software?
Compression
Encryption
Backup
Defragmentation
What is compression?
Compression involves applying an algorithm to reduce the space needed to represent a file or its contents.
What is encryption?
Encryption is designed to prevent unauthorised access to files by applying an algorithm to “scramble” data
What is backup?
Backup involves making copies of data that can be restored in the event of a data loss.
What is Defragmentation?
Defragmentation involves improving hard disk performance by applying an algorithm to reorganise data.
What is the purpose of the Operating system?
An operating system (OS) is a piece of system software which controls the hardware within a computer
What is the API?
Operating systems provide an application programming interface (API)
This is a set of code libraries that software developers can use to write applications for that operating system
What are different pieces of hardware controlled by?
Each piece of hardware is controlled by a manager
What does the User Interface (UI) manager do?
The user interface (UI) manager provides the user interface which allows users to control the computer
What does the device manager do?
The device manager allocates resources to external hardware devices and allows them to be used by applications
What does the memory manager do?
The memory manager controls the allocation of memory between applications
`What does the user manager do?
The user manager authenticates and separates users of the computer
What does the process manager do?
The process manager controls the allocation of central processing unit (CPU) cycles to multiple running applications
What does the file manager do?
The file manager controls the opening, reading and writing of files in secondary storage
What does WIMP stand for
WIMP stands for window-icon-menu-pointer
What are command line interfaces?
A command line interface (CLI) is an environment where the computer is controlled by typing text commands using the keyboard.
The computer cannot display graphics, only text.
CLIs use less memory than graphical interfaces.
What are Graphic User Interfaces (GUIs)?
Graphical user interfaces (GUIs) are more modern environments to work in
GUIs are usually based on the window-icon-menu-pointer paradigm or a multi-touch interface
What is the purpose of memory manager?
The memory manager controls the allocation of random access memory (RAM) to each running process.
If the memory manager fails to manage memory well, then the computer will slow down and might crash.
What is the purpose of the process manager?
Modern operating systems allow users to run multiple programs at once.
In reality, a CPU can only execute one process at a time. So the CPU must switch between processes so quickly that it seems that they are running simultaneously.
What is multitasking?
Modern operating systems allow multiple applications to run at once. This is known as multitasking.
For this to work, the operating system must manage how memory and CPU time is allocated to each running process
What is the purpose of the device manager?
The device manager keeps track of which devices are connected to which ports
The device manager also allows applications to read or write data to each device
What are peripheral devices?
Peripheral devices are devices that the device manager manages