Computer Systems Flashcards
Define the terms hardware and software and understand the relationship between them
Hardware is the physical stuff that makes up the computer system, like the CPU, motherboard, monitor and printer
Software is the programs or applications that a computer system, runs e.g. and operating system, word processor or a game
Explain what is meant by:
• system software
• application software.
Give examples of both types of software.
System software - performs the tasks needed to operate the hardware and provides services for other software e.g OS, game engines, utility programs (backup, encryption)
Application software - user benefit e.g. internet browsers, word processors, games
What is the need for, and functions of, operating systems (OS) and utility programs?
The operating system links the hardware and other software together and generally runs the computer system. It’s purpose is to create a user interface, provide a layer of security, manage the hardware and mange the applications installed.
What does the the OS handles management of?
Hardware and installed applications
Explain the role and operation of main memory and the following major components of the CPU
ALU - performs logic operations on the data such as AND, OR and NOT and binary shits. It does all the calculations such as addition, subtraction, compares the size of numbers and can do multiplication and division. It also contains the accumulator register.
CU - coordinates the activities of the CPU. It’s main job is to
Explain the role and operation of main memory and the following major components of the CPU
ALU - performs logic operations on the data such as AND, OR and NOT and binary shits. It does all the calculations such as addition, subtraction, compares the size of numbers and can do multiplication and division. It also contains the accumulator register.
CU - coordinates the activities 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 CPUE
Bus - A bus is a collection of wires through which data is transmitted from one component to another.
Registers - temporarily gold tiny bits of data needed by the CPU. They are super quick to read/write to, quicker than any other memory.
Clock - regulates circuits, produces signals that oscillate which is used by the CPU to define a set number of instructions executed per clock cycle
Explain the effect of the following on the performance of the CPU: • clock speed • number of processor cores • cache size • cache type
Clock speed - the number of instructions a single processor core can execute per second. The higher the clock speed, the greater the number of instructions that can be carried out per second.
Cores - Each core processes data independently of the rest, a CPU can have multiple cores on a single chip. The more cores a CPU has, the more instructions it can carry out at once, so the faster it can process a batch of data. When software is optimised, multiple cores allow multiple instructions to be executed simultaneously.
Cache size - very fast memory that stores regularly used data so that the CPU can access it quickly the next time it’s needed. The larger the cache, the more instructions can be accessed faster. L1 - fastest but lowest capacity.
Explain the Fetch-Execute-Decode cycle
The CPU continuously reads instructions stored in main memory and executes them as required:
• fetch: the next instruction is fetched to the CPU from main memory
• decode: the instruction is decoded to work out what it is
• execute: the instruction is executed (carried out). This may include reading/ writing from/to main memory
What are the differences between main memory and secondary storage?
Main memory is memory that is directly accessible by the CPU, e.g. RAM. It is volatile memory which means it loses it’s data when power is lost whereas secondary storage (ROM) is non-volatile so it can retain its data even if power is lost. Secondary storage is considered to be any non- volatile storage mechanism not directly accessible by the CPU.
What are the differences between RAM and ROM?
RAM (Random Access Memory) is the main memory in a computer, it can be read or written to. It loads open programs and operating software data currently in use from the slow secondary storage so it can be directly accessible by the CPU.
ROM (Read Only Memory) is non-volatile memory that can only be read. It contains the BIOS that a computer needs to properly boot up. It comes on a small factory chip built into the motherboard.
Why is secondary storage is required?
Needed so non-volatile memory is available. Computers have a limited amount of RAM and when RAM is full, computers need another location to put application data so it moves data that hasn’t been used recently to another location called secondary storage.
Explain the different types and operations of secondary storage
Solid state - non-mechanical flash memory which consists of digital data that retain data which can then be changed.
Optical - Binary data is stored on variations of height on the disks surface. To read the data, light is shined on the disk. Data is written with a laser burning into the pits into the disk.
Magnetic - Use read/write heads that contain electromagnets. Data magnetically in small areas called sectors within circular tracks. Parts of the surface is either magnetised or demagnetised and the read/write heads on a moving arm control this and are used to access sectors to read what state they are.
Discuss the advantages and disadvantages of solid state, optical and magnetic storage
Solid - Very fast, very reliable, don’t need defragmentation and are silent. They are expensive are generally have a smaller capacity than magnetic.
Optical - Fairly reliable and durable and are very portable. However they have a small capacity and can easily be damaged.
Magnetic - Large capacity, cheap to buy and reliable. However they are not durable, they are not portable and they generate a lot of heat and noise.
Explain the term “cloud storage”
It uses magnetic and increasingly solid state storage at a remote location where data is stored on multiple servers.
Explain the advantages and disadvantages of cloud storage when compared to local storage
They are durable, portable and cheaper for larger companies (reduced energy costs) but the services may not always be reliable and is more likely expensive for individual users.
