3. hardware

the CPU proceses instructions and data that are input into the computer so that the result can be output

the microporocessor is a type of intergrated circuit on a single chip

• arithematic logic unit- responsible for carying out mathamatical calculation • control unit- manages the other components

-PC: - MAR: - cir - MDR - ACC

-PC: holds the address (memory location) of the next instruction to be fetched.

s also used when reading and writing data to and from RAM. The MDR will contain the data to be written to RAM, or the data that has just been read from RAM.

holds the instruction which is currently being decoded or executed.

is used to hold the data being worked on by the ALU

The control bus carries control signals from the Control Unit to other components of the CPU. and read and write signals

the adress bus carries adresses from the memory adress register to the RAM, to indicade wgich adress will be selected. only 1 direction

a data bus carries data from the memory data register to the RAM during a write operation, the data bus carried data from the RAM to the memory data register during a read operation. bidirectional

-the pc contains the adress of the next instruction - the contents of the PC are copies to the MAR - the pc is incrimented by 1 so it still points to the next instruction - the adress bus carries the value in the MAR to the RAM - the control bus sends a ‘read’signal to RAM - the data bus carries the contents of the desired RAM adress froom the RAM to the MDR - the contents of MDR is sopies to the CIR - the control unit decodes data - ALU executes

• usually measured in GHz -determains the number of cycles a CPU can perform each second more speed can generate more energy and heat

a processer within the cpu. only 1 core can occur at a time.

the cache is extremely fast memory that is located within the CPU. it is used to store temporary copies of the data in most commonly accessed RAM locations.

• An instruction set is a list of all the commands that can be processed by a CPU and the commands are machine code

An embedded system is used to perform a dedicated function, e.g. domestic appliances, cars, security systems, lighting systems or vending machines. This is different to a general purpose computer that is used to perform many different functions, e.g. a personal computer (PC) or a laptop

shine a light at barcode and measure the reflected light to read the data- quick, accurate, efficient

uses a image sensore to measure light and take phototgraph, which is stored digitally on a device.

allows users to type text and numeric data- reduced number of mistakes, limited operations

allows sound to be input. the sound can be playback at any time

control curser on screen

represents small text characters using black and white pattern. store URLs. quick, requires internet, nfinate patterns

input data using finger- user friendly, select from a small range of options. resistive- uses very thin metal sheets over screen, pressure of contact complete ciruit capacitive- transparent layer sensitive to static electrical charge in the human body infrared- grid of infra red light over the screen. this grid is ivisable to users. light beams are broken info is detected.