Units, Numbers and Characters - Computing

Units, Numbers and Characters - Computing

1. UNITS

   • BIT - smallest unit of data, represented as a binary number, either 1 (true) or 0 (false)
   • BYTE - contains 8 bits, one keyboard character takes up 1 byte of storage
   • NIBBLE - 4 bits, 2 make a byte, less common
   • KILOBYTE - unit of storage capacity, 1024 bytes (or 1000), equivalent to 1024 characters on screen
     • The more detailed an image, the more kilobytes of storage it takes up
   • MEGABYTE - unit of storage capacity, 1,048,576 bytes or 1,024 kilobytes (or 1 million bytes/1000 kilobytes)
     • A typical MP3 song can be anywhere between 3 to 5 megabytes in size and a CD can store up to 650 megabytes of data.
   • GIGABYTE - 1024 megabytes, a DVD can store a film around 4-8 gigabytes and hard disks can hold typically 160+ gigabytes
   • TERABYTE - 1024 gigabytes, can store huge amounts of data
   • ANALOGUE DATA - on a continuous scale, used in the real world
     • Computers can only deal with digital data (0 or 1). Analogue data must be converted to digital using an ADC

2. NUMBERS

   • Denary number system: 0, 1, 2, 3, 4, 5, 6, 7, 8, 9
     • 'Base 10' number system
       • Multiply each digit on the left by a progressive factor of 10 in order to calculate its value e.g. '123' = 3 + (10 * 2) + (100 * 1)
   • Binary: 0 or 1
     • 'Base 2' number system
       • Multiply each digit on the left by a progressive factor of 2 e.g. '37' = 00100101 (1 * 1) + (2 * 0) + (4 * 1) + (8 * 0) + (16 * 0) + (32 * 1) = 37