Computer Measurements Data Measurement The base unit is the Bit, which is a number that can be only either 0 or 1. This is 2 possible states, ie binary. Binary is the fundamental basis of computing. 0 1 zero one off on false true no yes Unit Number of Bits Power of 2 Number Of Bytes Half Nibble 2 bits 2^1 1/4 byte Nibble 4 bits 2^2 1/2 byte Byte 8 bits 2^3 1 byte Half Word 16 bits 2^4 2 bytes Word 32 bits 2^5 4 bytes Double Word 64 bits 2^6 8 bytes Quad Word 128 bits 2^7 16 bytes Note: On some old CPU's, a Word is 16 bits, but Haxial uses the modern IBM PowerPC definitions, where a Word is 32 bits. Unit Equals Power of 2 Number of Bytes Kilobyte 1024 bytes 2^10 1024 bytes Megabyte 1024 kilobytes 2^20 1,048,576 bytes Gigabyte 1024 megabytes 2^30 1,073,741,824 bytes Terabyte 1024 gigabytes 2^40 1,099,511,627,776 bytes Petabyte 1024 terabytes 2^50 1,125,899,906,842,624 bytes Exabyte 1024 petabytes 2^60 1,152,921,504,606,846,976 bytes Zettabyte 1024 exabytes 2^70 1,180,591,620,717,411,303,424 bytes Yottabyte 1024 zettabytes 2^80 1,208,925,819,614,629,174,706,176 bytes Note: The marketing departments of some companies claim that a megabyte = 1,000,000 bytes, etc. In other words, they claim that it is a power of 10 system, not a power of 2 system. This is false and ridiculous because a byte is undisputedly a unit based on the binary / power of 2 system, ie a byte = 2^3 = 8 bits, NOT 10 bits. Therefore it makes sense that a megabyte should also be based on the same system (a power of 2). Saying a megabyte = 1,000,000 bytes is a crazy mix of power of 10 and power of 2. Marketing departments use 1,000,000 only because it makes the capacities of their devices seem bigger, but really it is false advertising, much in the same way that a 17" CRT monitor is not 17 inches. To abbreviate, use the first letter as a suffix. Alternatively, you can use the first letter and a 'B' for Byte. Abbrev 1 Abbrev 2 Full 16K 16 KB 16 Kilobytes 16M 16 MB 16 Megabytes 16G 16 GB 16 Gigabytes Note: If you append the 'B' for byte, make sure you use uppercase because some people use lowercase 'b' to mean bit. Definitions for kilobits, megabits etc are not listed here because Haxial deprecates their usage. Use kilobytes etc instead because they are more practical and easier to understand (a letter of the alphabet uses a byte of memory, a paragraph consisting of 300 characters uses 300 bytes of memory, etc). If you need to convert bits to bytes, then divide by 8 (because 8 is the number of bits in a byte). Further complicating matters, some people use a kilobit to mean 1000 bits (power of 10), and other people use a kilobit to mean 1024 bits (power of 2). Haxial recommends entirely dropping the use of kilobits and megabits. Time Measurement The base unit is the Second, which according to Système International is. The second is the duration of 9 192 631 770 periods of the radiation corresponding to the transition between the two hyperfine levels of the ground state of the caesium 133 atom. 1 second = 1,000 milliseconds = 1,000,000 microseconds = 1,000,000,000 nanoseconds = 1,000,000,000,000 picoseconds Data Speed Measurement Data speed is quantity over time. For example, 128K/sec means 128 kilobytes per second, which means that if you start counting the number of bytes being transmitted, and you do this for a time period of 1 second, then you will have counted 128 kilobytes.