In computing

Computing

Computing is usually defined as the activity of using and improving computer hardware and software. It is the computer-specific part of information technology...

, a pizza box is a style of case

Computer case

A computer case is the enclosure that contains most of the components of a computer...

 for computer

Computer

A computer is a programmable machine designed to sequentially and automatically carry out a sequence of arithmetic or logical operations. The particular sequence of operations can be changed readily, allowing the computer to solve more than one kind of problem...

s or network switches. Cases of this type tend to be wide and flat, normally one or two rack unit

Rack unit

A rack unit or U is a unit of measure used to describe the height of equipment intended for mounting in a 19-inch rack or a 23-inch rack...

s (1U or 2U, 1¾ or 3½ inch, 4.4 or 8.9 cm) in height, thus resembling pizza delivery boxes.

The first computers generally referred to as pizza box systems were high-end desktop systems, such as Sun Microsystems

Sun Microsystems

Sun Microsystems, Inc. was a company that sold :computers, computer components, :computer software, and :information technology services. Sun was founded on February 24, 1982...

 workstation

Workstation

A workstation is a high-end microcomputer designed for technical or scientific applications. Intended primarily to be used by one person at a time, they are commonly connected to a local area network and run multi-user operating systems...

s sold in the late 1980s, most notably the SPARCstation 1

SPARCstation 1

The SPARCstation 1, or Sun 4/60, is the first of the SPARCstation series of SPARC-based computer workstations sold by Sun Microsystems. It had a distinctive slim enclosure and was first sold in April 1989, with Sun's support for it ending in 1995.Based around a LSI Logic RISC CPU running at...

 and SPARCstation 5

SPARCstation 5

SPARCstation 5 or SS5 is a workstation sold by Sun Microsystems. It is based on the sun4m architecture, and is enclosed in a pizza-box chassis. A simplified, cheaper version of the SS5 was later released as the SPARCstation 4...

. Other notable examples are the SGI Indy

SGI Indy

The Indy, code-named "Guinness", is a low-end workstation introduced on 12 July 1993. Developed and manufactured by Silicon Graphics Incorporated , it was the result of their attempt to obtain a share of the low-end computer-aided design market, which was dominated at the time by other workstation...

, the NeXTstation

NeXTstation

NeXTstation was a high-end workstation computer developed, manufactured and sold by NeXT from 1990 until 1993. It ran the NeXTSTEP operating system. The NeXTstation was released as a more affordable alternative to the NeXTcube at about US $4,995 or about half the price...

, Macintosh LC

Macintosh LC

The Macintosh LC was Apple Computer's product family of low-end consumer Macintosh personal computers in the early 1990s. The original Macintosh LC was released in 1990 and was the first affordable color-capable Macintosh. Due to its affordability and Apple II compatibility the LC was adopted...

, and Amiga 1000

Amiga 1000

The A1000, or Commodore Amiga 1000, was Commodore's initial Amiga personal computer, introduced on July 23, 1985 at the Lincoln Center in New York City....

: most were considered to be among the highest performing computers of their generations.

The original SPARCstation 1 design included an expansion bus technology, SBus

SBus

SBus is a computer bus system that was used in most SPARC-based computers from Sun Microsystems and others during the 1990s...

, expressly designed for the form factor; expansion cards were small, especially in comparison to other expansion cards in use at the time such as VMEbus

VMEbus

VMEbus is a computer bus standard, originally developed for the Motorola 68000 line of CPUs, but later widely used for many applications and standardized by the IEC as ANSI/IEEE 1014-1987. It is physically based on Eurocard sizes, mechanicals and connectors , but uses its own signalling system,...

, and were mounted horizontally instead of vertically. PC compatible computers in this type of case typically use the PCI

Peripheral Component Interconnect

Conventional PCI is a computer bus for attaching hardware devices in a computer...

 expansion bus and are usually either limited to 1 or 2 horizontally placed expansion cards or require special low profile expansion cards, shorter than the PCI cards used in regular PCs.

The density of computing power and stackability of pizza box systems also made them attractive for use in data center

Data center

A data center is a facility used to house computer systems and associated components, such as telecommunications and storage systems...

s. Systems originally designed for desktop use were placed on shelves inside of 19-inch rack

19-inch rack

A 19-inch rack is a standardized frame or enclosure for mounting multiple equipment modules. Each module has a front panel that is wide, including edges or ears that protrude on each side which allow the module to be fastened to the rack frame with screws.-Overview and history:Equipment designed...

s, sometimes requiring that part of their cases be cut off in order for them to fit.

Since the late 1990s, pizza boxes are used almost exclusively in data centers or industrial applications where rack space and density are critical. Servers in this form factor, as well as higher end Ethernet switches, are now designed for rack mounting. Rack mount 1U computers come in all types of configurations and depths.

The pizza box style has mostly fallen out of use for desktop computing, as cooling and expansion challenges have made tower

Computer case

A computer case is the enclosure that contains most of the components of a computer...

 and minitower designs the de facto standard. Taller versions of the pizza box design exist, but these are usually known as "desktop cases"; they have roughly the same dimensions as a mini tower, but are designed to lay flat on a desk.

External links

• Pizza box in the Jargon File
  Jargon File
  The Jargon File is a glossary of computer programmer slang. The original Jargon File was a collection of terms from technical cultures such as the MIT AI Lab, the Stanford AI Lab and others of the old ARPANET AI/LISP/PDP-10 communities, including Bolt, Beranek and Newman, Carnegie Mellon...