Computer Systems Flashcards
What is hardware?
Hardware is the physical components that make up a computer system, such as a CPU and motherboard.
What is software?
Software is the programs that run on a computer (e.g operating systems).
What are the two types of software?
- System software: Software that is needed to communicate with the hardware and launch application software. (Examples include operating systems, utility software.)
- Application software: Programs launched from the operating system that help the user perform specific tasks. (Examples include word processors, web browsers, games.)
Computer systems can either be general purpose or dedicated systems. Explain what these mean. Give examples of both.
- General purpose: Designed to perform many tasks. Examples include PCs and tablets.
- Dedicated systems: Designed for one particular function. Examples include controlling the function of a dishwasher.
What are embedded systems?
A dedicated system which is part of a larger system. They are computers built into other devices, like dishwashers, microwaves and TVs.
What do embedded systems normally do?
What are the advantages of embedded systems?
- Embedded systems are often used as control systems. They monitor and control machinery in order to achieve a desired result.
- As they’re usually dedicated systems, and only serve one purpose, they are easier to design, cheaper to produce, and more efficient at doing their task than general purpose computers.
Define a computer system.
A computer system takes a set of digital inputs, processes them and creates a set of outputs, which is done by a combination of software and hardware.
What is the CPU? What is a CPU’s processing power dependant on?
- The Central Processing Unit. It is the brain of the computer, and processes all data and instructions.
- A CPU’s processing power is dependant on many characteristics, such as clock speed, number of cores, cache size and type.
What are the 6 main parts of a CPU?
- The Control Unit (CU)
- The Arithmetic Logic Unit (ALU)
- Cache
- The Clock
- Buses
- Registers
What is the control unit (CU)?
What is its main job?
What does it do?
- The control unit controls the CPU.
- Its main job is to manage the fetching, decoding, and execution of program instructions, by following the Fetch-Execute cycle.
- It controls the flow of data inside the CPU and outside the CPU.
Arithmetic Logic Unit (ALU)
- Does all the calculations in the CPU
- It completes simple addition, subtraction, and compares the size of numbers. It can do multiplications and divisions by using repeated addition and subtraction.
- It performs logic operations such as AND, OR, and NOT, and binary shifts.
- (Registers are used to store intermediate results of calculations.)
What is cache? How expensive is it? What does it store? Where is it found, and how does this determine its speed?
- Very fast memory in the CPU. Slower than registers, but faster than RAM.
- Stores regularly used data so the CPU can access it quickly whenever it’s needed.
- Caches have a very low capacity and are expensive compared to RAM and secondary storage.
- Speed is based on distance from the CPU.
- Some cache is on the motherboard, some is directly on the CPU.
The Clock
- The clock (quartz crystal) sends out a regular electronic pulses at a consistent rate, to synchronise all components in a CPU. (acting like a metronome).
- This pulse is used to synchronise when instructions will be carried out.
- The number of clock cycles per second is called the clock speed. (measured in gigahertz).
What are buses, and what are there different buses for?
- Buses are collections of wires that are used to transmit data between components of the CPU, and to other parts of the computer system.
- A processor may have separate buses for carrying data, instructions, and memory addresses.
Registers
- Small, high-speed storage locations that temporarily hold data and instructions.
- Super-quick to read/write to, quicker than any other form of memory.
