AT (form factor)

In the area of IBM compatible personal computers, the AT form factor referred to the dimensions and layout (form factor) of the motherboard for the IBM AT. Like the IBM PC and IBM XT models before it, many third-party manufacturers produced motherboards compatible with the IBM AT form factor, allowing end users to upgrade their computers for faster processors. The IBM AT became a widely copied design in the booming home computer market of the 1980s. IBM clones made at the time began using AT compatible designs, contributing to its popularity. In the 1990s many computers still used AT and its variants. Since 1997, the AT form factor has been largely supplanted by ATX.

Design

The original AT motherboard, later known as "Full AT", is 13.8 × 12 inches (351 × 305 mm), which means it will not fit in "mini desktop" or "minitower cases". The board's size also means that it takes up space behind the drive bays, making installation of new drives more difficult. (In IBM's original heavy-gauge steel case, the two 5-1/4" full-height drive bays overhang the front of the motherboard. More precisely, the left bay overhangs the motherboard, while the right bay is subdivided into two half-height bays and additionally extends downward toward the bottom of the chassis, allowing a second full-height fixed disk to be installed below a single half-height drive.)

Form factor

Form factor may refer to:

Science

Scattering theory

Forestry

Design

Epicyclic gearing

An epicyclic gear train consists of two gears mounted so that the center of one gear revolves around the center of the other. A carrier connects the centers of the two gears and rotates to carry one gear, called the planet gear, around the other, called the sun gear. The planet and sun gears mesh so that their pitch circles roll without slip. A point on the pitch circle of the planet gear traces an epicycloid curve. In this simplified case, the sun gear is fixed and the planetary gear(s) roll around the sun gear.

An epicyclic gear train can be assembled so the planet gear rolls on the inside of the pitch circle of a fixed, outer gear ring, or ring gear, called an annular gear. In this case, the curve traced by a point on the pitch circle of the planet is a hypocycloid.

The combination of epicycle gear trains with a planet engaging both a sun gear and an annular gear is called a planetary gear train. In this case, the annular gear is usually fixed and the sun gear is driven.

Form factor (mobile phones)

The form factor of a mobile phone is its size, shape, and style, as well as the layout and position of its major components. There are three major form factors – bar phones, flip phones, and sliders – as well as sub-categories of these forms and some atypical forms.

Bar

A bar (also known as a slab, block, candybar) phone takes the shape of a cuboid, usually with rounded corners and/or edges. The name is derived from the rough resemblance to a chocolate bar in size and shape. This form factor is widely used by a variety of manufacturers, such as Nokia and Sony Ericsson. Bar type mobile phones commonly have the screen and keypad on a single face. The Samsung SPH-M620 has a unique bar style, offering different devices on either side of the bar: a phone on one side, and a digital audio player on the other. Sony Ericsson also had a well-known 'MarsBar' phone model CM-H333.

Since mid 2010s, almost all the mobile phones come in bar form factor.

Brick

"Brick" is a slang term almost always used to refer to large, outdated bar-type phones, typically early mobile phones with large batteries and electronics. However, "brick" has more recently been applied to older phone models in general, including non-bar form factors (flip, slider, swivel, etc.), and even early touchscreen phones as well, due to their size and relative lack of functionality to newer models. Such early mobile phones, such as the Motorola DynaTAC, have been displaced by newer smaller models which offer greater portability thanks to smaller antennas and slimmer battery packs.