Flashcards in Computer systems, memory, storage and software Deck (22):
What is a computer?
A computer is a machine that processes data
Define hardware and software
Hardware is all the physical components of a computer, software is the program that a computer systems run
What is system software
System software is the software that controls how the computer function e.g. utility software and operating systems
What is application software?
Application sofware is software that is designed to perform a specific task
e.g. Word Processor
What are the five main parts of the CPU?
-The Control Unit
-The Arithmetic Logic Unit
What does the Control Unit do?
▪️The CU is in overall control of the CPU. It’s main job is to execute program instructions by following the fetch-decode-execute cycle
▪️It controls the flow of data inside the CPU and outside the CPU
What does the Arithmetic Logic Unit do?
▪️The ALU does all the calculations
▪️It completes simple addition and subtraction, compares the size of the numbers, and can do multiplications and divisions using repeated addition and subtraction.
▪️It performs logic operations and binary shifts
▪️Uses Registers to store intermediate results in calculations
What does the Cache do?
▪️The cache is very fast memory in the CPU. It is slower than the registers but faster than RAM
▪️It stores regularly used data so that it can be accessed quickly.
▪️The CPU checks the cache first if it needs data, if it’s not there it then fetches it from RAM
▪️Caches have a low capacity and are expensive compared to RAM and secondary storage
What does the Clock do?
▪️The Clock sends out a signal that continually cycles between 1 and 0, usually at a constant rate
▪️The signal is used to synchronise when instructions will be carried out (like a metronome)
▪️The number of clock cycles per second is called the clock speed
What do buses do?
▪️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 addresses
What di registers do?
▪️They are a form of memory which is really quick to read and write to
▪️They are quicker than any other form of memory
What happens during the ‘FETCH’ of the FECTH-DECODE-EXECUTE cycle?
1. The control unit reads the memory address of the next CPU instruction
2.The instruction stored in that address is copied from the memory to one of he registers
3.The memory address in the control unit is incremented to point to the address of the next instruction, ready for the next cycle
What happens during the ‘DECODE’ of the FETCH-DECODE-EXECUTE cycle?
1. The instruction that was copied from memory is decided by the control unit
2. The control unit prepares for the next step e.g. by loading other values into the registers
What happens during the ‘EXECUTE’ of the FETCH-DECODE-EXECUTE cycle?
The instruction is performed.
what is RAM?
RAM is high speed, volatile memory. It can be read or written to and is the main memory of the computer
what is ROM?
ROM is non-volatile memory and can only be read
Give examples of when RAM is used
▪️When a computer boots up, the operating system is copied from secondary storage to RAM
▪️When software applications, documents and files are opened, hey are copied from secondary storage to RAM
Give examples of when ROM is used
▪️it tells the computer to boot up and power on
▪️tells the computer to copy the operating system to RAM
How does Clock speed affect the CPU performance?
▪️the higher the clock speed, the more instructions can be carried out per second
▪️some CPUs can be overclocked yo make it run at a higher clock speed than the factory-set rate. This can cause the computer to overheat and crash, resulting in permanent damage to the system
How do CPU cores affect the CPU performance?
▪️The more cores a CPU has! the more instructions it can cary out at once, so the faster it can process batch data
How does Cache size affect the CPU performance?
▪️The larger the CPU cache, the faster access the CPU has to data that it needs to process