Jargon is the set of terms and expressions that have defined meaning within a field but lack that meaning (or perhaps any meaning) outside of that field. Computing’s jargon is primarily based on English words with computing-specific meanings which may or may not be related to the English meanings of those words.

On this page are terms I have defined in class and which I expect you to understand.

Abstract

A continuous property; something can be more or less abstract, but can’t be simply abstract or not.

More abstract means described in bigger steps or with elided details. To make something less abstract, you answer how do we do step $x$, adding more detail. To make something more abstract, you replace several steps with a generalization that describes them all.

Algorithm

Unambiguously-defined steps to accomplish some task.

The word algorithm is a Latinization of the name of Muḥammad ibn Mūsā al-Khwārizmī who wrote books that Europeans adopt the ideas of algorithms with place-value numbers. Algorithms themselves long predate his work.

Analog

Often used to mean simply not digital, or the part of the world that is not computers.

Sometimes used to mean a signal with a meaning based on being analogous to (directly or naturally representing, not using symbols but more intrinsic properties like quantity or frequency) the thing is is describing.

Backwards compatibility

A new system is backwards compatible with an old system if data created by/for the old system works without modification in the new system.

Base

Place-value number systems are defined by a single integer called their base. The base tells us

• How many digits the system uses (including 0)
• The value multiple for moving a digit one place to the left

The most popular bases are:

• Base 2, also called binary with digits called bits, used to build computer processors.
• Base 10, also called decimal, used by humans in most modern cultures.
• Base 16, also called hexadecimal or hex, used by computing professionals to communicate binary values more easily.
• Base 256, with digits called bytes, used to build computer memory, storage, and communication devices and protocols.

Binary

Multiple meanings:

• The base-2 number system.
• A program that is ready to be run directly on a processor without further translation.
• Any computer file containing non-textual information.

When it is necessary to distinguish that a number is written in binary, it is traditional to precede it with 0b; thus 0b1101 means a binary number with digits 1101 and represents the value thirteen.

Bit

A single digit in base 2: either 0 or 1.

The word bit is a portmanteau of binary digit.

Byte

A group of 8 bits. Equivalently, a group of 2 hex digits. Equivalently, a number between 0 and 255 (inclusive).

When it is necessary to write out a byte for human viewing, it is traditional to write it as two hex digits; thus 0D means a byte with the value thirteen and F3 means a byte with the value two hundred forty-three.

Digital

Represented or operating using a set of discrete symbols called digits, rather than using continuous or analog signals.

Because of the prevalence of programmable general-purpose digital computers, digital is sometimes used as a synonym for done with computers.

Float

Short for floating-point number, a float is the binary version of scientific notation stored as three parts:

• • or ‒
• An exponent
• The rest of the number (the significand or mantissa)

For example, 56⅔, which in binary is 111000.1010101010101010…, stored as a float with 8-bit significand would be +1.1100010 × 2¹⁰¹ (or in decimal as 1.765625 × 2⁵).

Gate

An abstraction of a group of transistors that implement some simple operation on a small number of bits.

The most commonly discussed gates are and, or, not, and xor. For some specific hardware cases, nand and nor are also used.

General-purpose

One of the key qualifiers of a computer, indicating that the computer hardware is capable of doing any information-processing task that any other computer can do.

The Church-Turing thesis posits the existence of general-purpose computers, and of related Turing-complete systems and forms of expression that are capable of describing the operation of general-purpose computers. While not formally proven, this thesis is widely accepted as true.

One consequence of the fact that almost all computers are general-purpose is that new computer technologies (like quantum computers) might differ from others in efficiency and speed, but not in the set of tasks they could eventually do, given unlimited time and storage.

Hex

A common abbreviation for hexadecimal.

Hexadecimal

A group of 4 bits. Equivalently, a number between 0 and 15 (inclusive).

Hexadecimal digits are typically represented as 0, 1, 2, 3, 4, 5, 6, 7, 8, 9 (with the same meanings they have in decimal) and A, B, C, D, E, F (meaning ten through fifteen in the order listed). Capitalization of the letters is not important:

When it is necessary to distinguish that a number is written in hexadecimal, it is traditional to precede it with 0x; thus 0x10E means a hexadecimal number with digits 10E and represents the value two hundred seventy.

Metadata

Data about the (main) data.

For example, in an image file the color of each pixel is the main data; information about the camera that took the image is metadata.

Many file formats store metadata along with the data, and many applications ignore most of the metadata.

Overflow

Most numbers in computers are represented in a fixed number of bits. If math would produce a number that requires more bits than that, the number overflows. What happens after overflow depends on the kind of number:

• For integers, the most common is to simply discard the digits that won’t fit; so 10011 stored in 4 digits would become 0011.

• For floats, when the exponent overflows the number changes into a special infinity value. It loses its ability to engage in most math, but is still clearly a big number.

Programmable

One of the key qualifiers of a computer, indicating that the specific computations it performs is not fixed when it is created but rather can be specified as inputs to the computer.

Usually, programmable is also assumed to mean that the program it follows is stored inside the computer’s memory and can be an entire algorithm, not just one of a machine-defined set of operations selected by simple switches and buttons.

Type

How the bits inside some piece of data are converted into meaning.

For example, the bits 01100110 could have many meanings. If they are interpreted with the data type integer they mean 102. If they are interpreted with the data type UTF-8 character they mean lower-case F (f). The bits (the information we actually store in the computer) have not changed, only how we interpret it.