Computer Systems <3

2^n -1

2^n -1 (÷2)

A real number is a number with a decimal point. A real number can be positive or negative.

they only used one byte they were limited to 256 characters

• All current and historic languages can be represented and understood by all modern computing devices; • The first 128 characters are identical to ASCII which maintains backwards compatibility with older files.

• UniCode takes up much more storage space than ASCII • The UniCode standard only defines what each number means and leaves it to software developers to decide precisely how each character looks on their system.

A bitmap is a representation of a graphic using a grid of bits to store the information about the colour of each pixel in an image. Bitmapped images appear as pixels.

When using colours, multiple bits are stored for each pixel. The more bits user per pixel, the more colours can be stored.

Stores them as a description of the shapes in the image to enable them to be re-drawn for recreating that image rather than storing them as individual pixels.

Central Processing Unit

Buses are the lines which connect the CPU to the main memory.

The address bus is a unidirectional (1 way) bus

Data bus is a bi-directional (2 way) bus

the processor sets up the address register with the address of the memory location to be accessed, the processor activates the read or write line on the control bus, and data is then transferred to or from the data register via the data bus, Memory location address Activates read/write line Data is transferred

2^n - n being number of lines 16 lines = 2^16 possible memory locations;

Transfer the contents of the Program Counter to Memory Address Register Increment the Program Counter Activate Read line (thereby transferring instruction to the data register) Transfer contents of data register to the instruction register ready for decoding Decode Instruction Execute Instruction

A computer system that would need some level of human-like intelligence to run :)

Smart thermostats Smart heating systems Activicty sensors

Intelligent transport systems Navigational Systems

Start-stop systems GPS sensors Engine Control Units

The computer misuse act 1990

To get adverts you actually want

A Denial of Service (DOS) attack is when a website or a network is targeted, with the intention of making it unavailable to users.

Encryption means that before information is sent or stored electronically, (for example in an email), it is scrambled using a mathematical process which turns it into something that looks like nonsense. This means that if anyone steals the information it will be meaningless to them. It will look like gobbledygook.