Section 3 Hardware Flashcards

Question

CU

Answer 1

Control unit is the internal part of the CPU and it controls the flow of data through the CPU. It also controls the interactions between the different parts of the CPU. It instructs different components how to respond to instructions.

Answer 2

Current Instruction Register (CIR) contains the current instruction being processed in the CPU.

Answer 3

Program counter (PC) is a register contains the address of the next instruction to be executed.

Answer 4

Immediate access stores (IAS) is the memory found inside a CPU and is used to hold not only data but also the instructions needed to process that data. It is also more commonly known as the CPU memory. The CPU needs to hold the data and instructions here before processing.

Answer 5

A bus that carries signals relating to addresses between the processor and the memory. It is uni-directional (signals travel in only one direction).

Answer 6

A bus that sends data between the processor, the memory unit and the input/output devices. It is bi-directional (data travels both directions).

Answer 7

A bus that carries signals relating to the control and coordination of all activities within the computer. It is both uni-directional and bi-directional due to internal connections within the computer).

Answer 8

1. The PC (program counter) contains the address of the next instruction to be fetched. 2. The address contained in the PC (program counter) is copied to the MAR (memory address register) via the address bus. 3. The instruction is then copied from the memory location contained in the MAR (memory address register) and is placed in the MDR (memory data register). 4. The entire instruction is then copied from the MDR (memory data register) and placed in the CIR (current instruction register). 5. The value in the PC (program counter) is then incremented so that it points to the next instruction to be fetched. 7. The instruction is finally decoded and is then executed.

Answer 9

A computer’s internal storage. Data is stored in primary memory when it is waiting to be processed. Capacity is quite small. Primary memory is separated into Random Access Memory (RAM) and Read Only Memory (ROM).

Answer 10

RAM is primary memory that holds data to be processed and programs that are in use. This means that RAM is storage that data can be written to and read from. Data stored here is volatile and will be erased when the computer is switched off. RAM can range in capacity from a few bytes to gigabytes.

Answer 11

ROM is primary memory that can be read from but not written to. Unlike RAM, ROM does not lose its contents when the computer’s power is switched off. It is non-volatile. There are three main types of software on ROM; firmware, bootstrap and EPROM. ROM tends to be much smaller in capacity.

Answer 12

Secondary Storage is where software and data is stored when it is not in use by the computer. It is stored on a more permanent basis and can be over-written as necessary. Secondary Storage is not directly accessible to the processor – data first has to be transferred into RAM. It is slower to read data from and write data to as it needs to be transferred to RAM. Can be up to terabytes in capacity. Three main types: Magnetic, Optical and Solid State.

Answer 13

Hard Disk Drives consist of several disks known as platters. These can be made from metal or glass. They have a magnetised coating on which the data dots are stored. These are the most common form of secondary storage.

Answer 14

Magnetic storage devices read, write and erase data by using electromagnets and magnetic fields to control tiny magnetic dots of fata. The dots represent binary.

Answer 15

CD are an early, but still used, optical medium. It uses a red laser to read the land and pits of the disc. It operates by: * Red laser is used. * Laser shines onto the surface of the disk. * It is rotated at a constant speed to be read. * Surface is covered in a track (that spirals from the centre)

Answer 16

DVD devices use a higher frequency laser than CD devices. The higher frequency allows the pits and land to be packed together onto the tracks. This allows more data to be stored. DVDs have more than one reflective layer on which data can be stored. (digital video/versatile disc)

Answer 17

Blu-Ray devices use a blue-violet laser that operates at a shorter wavelength than the red lasers used in CD and DVD devices. This give more precision when writing to and reading from a disk. This means that data can be packed even closer together than when using a DVD device. Blu-Ray Discs have more than one reflective layer on which data can be stored.

Answer 18

Optical storage devices read data by shining a laser beam onto the surface of plastic disks. The disks are coated with aluminium to make them reflective. Data is written on the track by using a laser to make indetations known as pits. These pits represent binary data. The areas in between pits are known as land.

Answer 19

Solid State Storage has no moving parts. Instead, it uses high-speed flash memory. They are physically quite small in size but have the highest transfer rate of data. They are expensive to produce.

Answer 20

A solid-state equivalent of a hard disk drive.

Answer 21

A solid-state card used to store and transfer data. (secure digital)

Answer 22

Off-line Storage is any non-volatile storage device that is discnonnected, or removed, from a computer. Typical examples would include CD, DVD, Blu-Ray Disc, USB RAM sticks, External Hard Drives and Magnetic Tape.

Answer 23

analog to digital converter

Answer 24

Light Crystal display - electronic display using properties of liquid crystals