1. Bits and Bytes IGCSE

2. A binary number is either a 0 or a 1 and is known as a 'bit' or b inary dig it. However, the CPU cannot deal with just one bit at a time, it is just too small. It usually deals with 8 bits at a time, which is known as a Byte. However, the CPU cannot deal with just one bit at a time, it is just too small. It usually deals with 8 bits at a time, which is known as a Byte. 11100101 is a byte, 10000111 is also a byte, or any other combination you can think of which contains 8 zeros and ones.

3. Why does all this matter? We often need to process words, so the computer must be able to store letters and other keyboard characters. This is done by making up a code. Each number represents a character. One common code is A=65, B = 66 and so on. This is called ASCII code or A merican S tandard C ode for I nformation I nterchange. One common code is A=65, B = 66 and so on. This is called ASCII code or A merican S tandard C ode for I nformation I nterchange. Each ASCII character occupies just one byte. The eight bit binary code or byte which represents the letter A is 0 1 0 0 0 0 0 1 The word JOHN would take 4 bytes of memory to store.

4. RAM can store millions of bytes. So of course all that information needs to be accessed by the CPU. It does this through a method called, 'addressing'. Every location in RAM has a unique address. Each storage location (address) contains a byte which represents data in the form of: –a number –a character or string of characters –a computer instruction –part of a picture –the address of a location in store But remember - all this information is stored as strings of 1s and 0s i.e. binary code

5. K is short for kilo 1Kb is one kilobyte K is short for kilo 1Kb is one kilobyte M is short for mega. 1 Mb is one megabyte. M is short for mega. 1 Mb is one megabyte. K is short for kilo 1Kb is one kilobyte K is short for kilo 1Kb is one kilobyte M is short for mega. 1 Mb is one megabyte. M is short for mega. 1 Mb is one megabyte. QuantityInformation 8 bits = 1 byte. This is the lowest 'data' level and is a series of 0s and 1s, e.g. 00111010 = 1 byte with each 0 or 1 equal to 1 bit. Each keyboard character = 1 byte. Each number, letter and keyboard symbol is represented by a series of 8 bits (each, of course, is different). 1000 keyboard characters = 1000 bytes or 1 KB (kilobyte). In reality it is really 1024 bytes which make a kilobyte, but generally people refer to 1000 bytes as a kilobyte. 1000 kilobytes = 1 MB (1 million keyboard characters). Floppy disks have a capacity of 1.44 MB CD ROM disks have a capacity of 650 MB. 1000 megabytes = 1 GB (gigabytes or 1 billion characters) DVD disks can hold between up to 4.7 GB of data. K is short for kilo 1Kb is one kilobyte M is short for mega. 1 Mb is one megabyte.

6. The Alphabet in Binary Code Letter Letter Binary Code A01000001 B01000010 C01000011 D01000100 E01000101 F01000110 G01000111 H01001000 I01001001 J01001010 K01001011 L01001100 M01001101 N01001110 O01001111 P01010000 Q01010001 R01010010 S01010011 T01010100 U01010101 V01010110 W01010111 X01011000 Y01011001 Z01011010 Letter Letter Binary Code a01100001 b01100010 c01100011 d01100100 e01100101 f01100110 g01100111 h01101000 i01101001 j01101010 k01101011 l01101100 m01101101 n01101110 o01101111 p01110000 q01110001 r01110010 s01110011 t01110100 u01110101 v01110110 w01110111 x01111000 y01111001 z01111010