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Computer Science
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- 1What is an input device?An input device is any device that allows data to be input onto a computer
- 2Examples of input devicesKeyboard keys,
Computer mouse,
Microphone on mobile phone,
Barcode scanner,
Buttons on a calculator,
Buttons on a till, - 3Difference between hardware and softwareHardware are the physical parts on a computer you can touch whereas software are the programmes stored on a computer which you can't touch.
- 4Definition of a computer systemA computer system is able to take a set of data inputs, process them and produce outputs.
- 5What is an embedded system?An embedded system is a computer that has been built to solve only a few specific problems and is not easily changed.
- 6Storage sizesBit
Nibble
Byte
Kilobyte
Megabyte
Gigabyte
Terabyte - 7What is CPU?The CPU (Central Processing Unit) is responsible for executing a sequence of stored instructions called a programme. This programme will take inputs from an input device, process the input and output the results into an output device.
- 8Fetch Execute CycleThe purpose of the CPU is to process data then it fetches and executes instructions from main memory (RAM) which is used to decode data. It is a continuous cycle.
- 9What is Clock Speed?Clock Speed is the number of instructions a processor can carry out per second. It is measured in Hz (number of times a clock ticks per second)
- 10Clock Speed measurements1MHz = 1 million Hz (1 million instructions per second)
1GHz = 1 Billion Hz (1 million instructions per second) - 11CoresThe number of cores affect performance of a computer system. Doubling the number of cores, doubles the number of instructions fetched - executed per second. More cores increases performance.
- 12RAMThe main memory of the computer
Volatile. It stores the data you are working on. RAM uses transistors to turn on or off access to a capacitor at each intersection. - 13SRAM (Static RAM)- It is random access memory that retains data bits in the memory
- It retains data as long as power is being supplied
- Does not have to be periodically refreshed - 14DRAM (Dynamic RAM)- Stores each bit of data in a separate capacitor
- The capacitor can be either charged or discharged
- Most common type of memory used today - 15ROMROM is non volatile. ROM uses diodes to connect the lines if its 1. ROM retains its contents even when the computer is turned off.
- 16Virtual Memory- When there is not enough RAM
- Uses a section of the hard disk as a temporary store
- The computer can take some programmes out of RAM - 17Memory size comparison8 bits = 1 byte
1024 bytes = 1 kilobyte
1024 kilobytes = 1 megabyte
1024 megabytes = 1 gigabyte
1024 gigabytes = 1 terabyte - 18What does a hard disk store?A hard disk stores:
the operating system
software applications or programs
the majority of your data files. - 19BinaryWe need to use a numbering system with just two values, in this case 1 and 0 to represent the two states. This is called a binary number system. So we can say that a 1 represents a switch that is on and 0 represents a switch that is off.
- 20Binary codes for a Bit and a ByteA 'bit' is the smallest unit of data that can be stored. Each 'bit' is represented as a binary number, either 1 or 0.
A 'byte' contains 8 bits, so for example, it could be stored as 11101001. - 21What is a logic gate and how does it work?The cpu fetches, decodes and executes instructions from memory. Electronic signals are detected by the CPU. The cpu recognises binary. The processor is made up of lots of logic gates, which are used to make decisions. They takes an input and output a result.
- 22What is Bootstrap?Bootstrap is the process of starting a computer. It also refers to the program that initializes the operating system during start up. It is the process of loading a set of instructions when a computer is first turned on or booted.
- 23Static RAMRandom access memory that retains data bits in the memory. It retains data as long as power is being supplied.
- 24Dynamic RAMStores each bit of data in a separate capacitor. The capacitor can be either charged or discharged.
- 25What is ROM used for?ROM is used in any technology devices as well as computers. ROM is non volatile which means it is not lost when power is removed.
- 26What is RAM used for?It is used to store data which can then be retrieved at a later date..
- 27Hard Disk DriveAll of your data files are stored on it. The data is stored in this magnetic metal. Can be terabyte or more. Very reliable as long as its not been deleted.
- 28Optical media (DVD)Amongst the most common methods of copying. Similar to a CD in that it is an optical device and that a laser is used to store the data and read the data. A single layer DVD can store about 4.7GB of data. A double layer DVD can hold over 9GB of data.
- 29Optical media (CD)The data is burned onto the surface of the disk using a laser beam in the CD drive. A laser beam is also used to read the data stored on the disk
Store around 650MB of data - 30What does BIOS stand for and what is its function?BIOS stands for Basic Input Output System. it is the common use of flash memory
- 31Volatile MemoryVolatile memory is computer storage that only maintains its data while the device is powered. Most RAM (random access memory) used for primary storage in personal computers is volatile memory.
- 32Secondary storageSecondary storage are storage devices that are not constantly accessible by a computer system. The devices and media must be either plugged in or inserted into a computer in order to be accessed by the system.
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- Fichas sobre Computer Science, creado por helling.g18 el 14/01/2016.
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