Sign up
Please tick the below box to proceed
I agree (or if I am under 13 my parent or guardian agrees on my behalf) to the terms and conditions of use and that:
- My test statistics may be published on the site leaderboard against my username
- My teacher(s) can review my test scores
- I can receive feedback on my tests from my teacher(s)
Please tick this box to proceed
Already have an account? Sign in
Preview lessons, content and tests
Computer Science & Programming solved. All in one platform.
1. To trial the platform and take tests, please take a few seconds to SIGN UP and SET UP FREE.2. Searching for something specific? See our text overview of all tests. Scroll right for levels, and lists. 3. Student and Teacher User Guides | Schemes of Work | Real Teacher use Videos |
Join 36000+ teachers and students using TTIO.
Units of Information
A bit is a binary digit, the smallest increment of data on a computer. A bit can hold only one of two values: 0 or 1, corresponding to the electrical values of off or on, respectively.
Because bits are so small, you rarely work with information one bit at a time. Bits are usually assembled into a group of eight to form a byte. A byte contains enough information to store a single ASCII character, like "h".
A kilobyte (KB) is 1,024 bytes, not one thousand bytes as might be expected, because computers use binary (base two) math, instead of a decimal (base ten) system.
Computer storage and memory is often measured in megabytes (MB) and gigabytes (GB). A medium-sized novel contains about 1 MB of information. 1 MB is 1,024 kilobytes, or 1,048,576 (1024x1024) bytes, not one million bytes.
Similarly, one 1 GB is 1,024 MB, or 1,073,741,824 (1024x1024x1024) bytes. A terabyte (TB) is 1,024 GB; 1 TB is about the same amount of information as all of the books in a large library, or roughly 1,610 CDs worth of data. A petabyte (PB) is 1,024 TB. 1 PB of data, if written on DVDs, would create roughly 223,100 DVDs, i.e., a stack about 878 feet tall, or a stack of CDs a mile high. Indiana University is now building storage systems capable of holding petabytes of data. An exabyte (EB) is 1,024 PB. A zettabyte (ZB) is 1,024 EB. Finally, a yottabyte (YB) is 1,024 ZB.
TED Talk: How computer memory works