Flashcards in Computer Systems Deck (25):
Define the term software.
Comprises all the programs that are written to make computers function.
Define the term hardware.
The electrical or electromechanical parts of a computer, and its input, output and storage device.
Explain what is meant by system software.
Software needed to run the computer's hardware and application programs.
Explain what is meant by application software.
Consists of programs that perform specific user-oriented tasks.
Give examples of system and application software.
System software: OS, utility programs, libraries, programming language translators.
Application software: microsoft word, spreadsheet, adobe browser etc
Understand the need for, and function of operating systems (OS).
Disguises the complexities of managing and communicating with its hardware from the user via an Application Programming Interface (API).
Describe the need for, and function of utility programs.
Makes it easier for the user to use the computer or provides housekeeping functionality.
- Security utilities that keep your data safe.
- Disk organisation utilities that organise your files into folders and tidy up the desk.
- Data compression utilities
- File backup utilities
How does the OS handle management of the processor(s)?
With computers able to run multiple applications simultaneously, OS is responsible for allocating processor time to each one as they compete for the CPU.
While one application is busy using the CPU for processing, OS queues up next process required by another application to make the most efficient use of the processor.
How does the OS handle management of the memory?
When a program is running it must be in the computer's main memory, and the OS must manage where in memory each program and the data it needs will go.
How does the OS handle management of the I/O devices?
When a user gives an instruction to print, the I/O management function takes over + controls the sending of the data to be printed from memory to the device driver.
How does the OS handle management of the security?
OS security includes many methods to ensure safety from threats and attacks.
- Controlling access to a computer by setting up passwords for different users.
- Setting different access rights + privileges for different users
- Automatically downloading updates for OS to ensure security loopholes are patched
- Encrypting files that are stored on the hard disk
Explain the Von Neumann architecture.
In the Von Neumann Architecture:
- program is stored in main memory + instructions are fetched and executed sequentially.
- there is a single memory (+ bus system) for accessing both data and programs.
Explain the role and operation of the arithmetic logic unit.
The ALU carries out following functions:
-Logical operations: AND, OR and NOT gates
-Shift operations: The bits in a computer word can be shifted left or right by a certain number of places.
-Arithmetic operations: Includes addition, subtraction, multiplication and division.
Explain the role and operation of the control unit.
Coordinates all the activities taking place inside the CPU. Functions:
- Controls execution of instructions in the correct sequence
- Decodes instructions
- Regulates + controls processor timing using regular pulses from the system clock
- Sends + receives control signals to and from other devices within the computer.
Explain the role and operation of the clock.
System clock controls processor timing, switching between zero + one at rates exceeding several million times per second. Synchronises all CPU operations.
- Clock frequency is the number of clock cycles which occur each second.
Explain the role and operation of the bus.
Buses are internal connections that pass data between the components of the CPU.
Data and instructions are passed between registers and other components along these buses.
Explain the effect of the clock speed on the performance of the CPU.
- All processor activities begin on a clock pulse.
- One clock cycle per second = 1 Hz
- Clock speed is measured in GHz = one billion cycles per second
- The greater the clock speeds, the faster instructions will be executed.
Explain the effect of the number of processor cores on the performance of the CPU.
A PC with a multi-core processor, executing many tasks at the same time, will operate faster than a single-core processor.
Explain the effect of the cache type on the performance of the CPU.
Cache makes any type of data frequently used by the CPU available much more quickly. The performance of the CPU increases as the processor has to access main memory less often, so it works faster.
Understand and explain the Fetch-Execute cycle.
Fetch - Address A of next instruction is fetched from the register where it is held. This register is incremented so it points to next instruction to be fetched. Instruction at address A is fetched from memory + put into a special register ready to be decoded.
Decode - The Control Unit decodes the instruction to see what has to be done next.
Execute - This instruction is executed.
Understand the differences between main memory and secondary storage.
-Main memory is accessed directly by the CPU, but secondary storage isn't.
Explain the differences between main memory and secondary storage.
Main memory is accessed directly by the CPU, ss isn't.
Ss is non-volatile, holds more data + relatively inexpensive per MB.
Ss have slower access speeds than main memory.
Explain the differences between RAM and ROM.
RAM is volatile, ROM is non-volatile.
RAM stores user data/programs/part of OS which is currently in use. ROM is used to store BIOS/bootstrap loader which is required at start-up of computer.
Memory in RAM can be written to or read from, ROM is read-only.
Why is secondary storage required?
For long term storage, e.g. programs, photographs, music, projects etc.