Desktop replacement computer
Encyclopedia
A desktop replacement computer (DTR) is a personal computer
that provides the full capabilities of a desktop computer
while remaining mobile
. They are often larger, bulkier laptop
s. Because of their increased size, this class of computer usually includes more powerful components and a larger display than generally used in smaller portable computers and can have a relatively limited battery capacity (or none at all). Some use a limited range of desktop components to provide better performance at the expense of battery life. These are sometimes called desknotes, a portmanteau of the words "desktop" and "notebook", though the term is also applied to desktop replacement computers in general.
s of the early-to-mid 1980s, such as the Osborne I, Kaypro II, the Compaq Portable
and the Commodore
Executive 64
(SX-64) computers. These computers contained the CPU
, display
, floppy disk drive and power supply
all in a single briefcase-like enclosure. Similar in performance to the desktop computers of the era, they were easily transported and came with an attached keyboard that doubled as a protective cover when not in use. They could be used wherever space and an electrical outlet were available, as they had no battery.
The development of the laptop
form factor gave new impetus to portable computer development. Many early laptops were feature-limited in the interest of portability, requiring such mobility-limiting accessories as external floppy drives or clip-on trackball
pointing devices. The first laptop that could be used as an only computer was the PowerBook 500 series
; with its built in Ethernet, video, SCSI, ADB and serial ports, it duplicated the functionality of the desktop models without requiring an external docking station
.
The development of the modern desktop replacement computer came with the realization that many laptops were used in a semi-permanent location, often remaining connected to an external power source at all times. This suggested that a market existed for a laptop-style computer that would take advantage of the user's reduced need for portability, allowing for higher-performance components, greater expandability, and higher-quality displays. Desktop replacement computers are also often used with a port replicator, to fully enjoy the desktop comfort.
Using a laptop form factor, however, desktop replacements still often suffer from limitations similar to those of more mobile laptops. They usually lack the ability to accept standard PCIe
expansion cards, limiting their expandability somewhat. While desktop replacements can offer better cooling than other laptops, they rarely dissipate heat efficiently enough to allow for high-end desktop-class components, and thus may not reach the same performance levels as desktop computer
s.
Desktop replacement computers are, with a few exceptions, difficult to upgrade compared to desktop computers, with many of their major components (such as the display) integral to the design of the machine, and others (such as the CPU and GPU) often being hard to access and replace.
A small segment of desktop replacements do not include a battery as a standard feature, while some do not include ExpressCard
support. They have the same limitations on serviceability as laptops, and can rarely use identical components to a desktop computer.
Personal computer
A personal computer is any general-purpose computer whose size, capabilities, and original sales price make it useful for individuals, and which is intended to be operated directly by an end-user with no intervening computer operator...
that provides the full capabilities of a desktop computer
Desktop computer
A desktop computer is a personal computer in a form intended for regular use at a single location, as opposed to a mobile laptop or portable computer. Early desktop computers are designed to lay flat on the desk, while modern towers stand upright...
while remaining mobile
Mobile computing
Mobile computing is a form of human–computer interaction by which a computer is expected to be transported during normal usage. Mobile computing has three aspects: mobile communication, mobile hardware, and mobile software...
. They are often larger, bulkier laptop
Laptop
A laptop, also called a notebook, is a personal computer for mobile use. A laptop integrates most of the typical components of a desktop computer, including a display, a keyboard, a pointing device and speakers into a single unit...
s. Because of their increased size, this class of computer usually includes more powerful components and a larger display than generally used in smaller portable computers and can have a relatively limited battery capacity (or none at all). Some use a limited range of desktop components to provide better performance at the expense of battery life. These are sometimes called desknotes, a portmanteau of the words "desktop" and "notebook", though the term is also applied to desktop replacement computers in general.
Origins
The forerunners of the desktop replacement were the portable computerPortable computer
A portable computer is a computer that is designed to be moved from one place to another and includes a display and keyboard. Portable computers, by their nature, are generally microcomputers. Portable computers, because of their size, are also commonly known as 'Lunchbox' or 'Luggable' computers...
s of the early-to-mid 1980s, such as the Osborne I, Kaypro II, the Compaq Portable
Compaq Portable
The Compaq Portable was the first product in the Compaq portable series to be commercially available under the Compaq Computer Corporation brand . It was the first IBM PC compatible portable computer...
and the Commodore
Commodore International
Commodore is the commonly used name for Commodore Business Machines , the U.S.-based home computer manufacturer and electronics manufacturer headquartered in West Chester, Pennsylvania, which also housed Commodore's corporate parent company, Commodore International Limited...
Executive 64
Commodore SX-64
The Commodore SX-64, also known as the Executive 64, or VIP-64 in Europe, is a portable, briefcase/suitcase-size "luggable" version of the popular Commodore 64 home computer and holds the distinction of being the first full-color portable computer....
(SX-64) computers. These computers contained the CPU
Central processing unit
The central processing unit is the portion of a computer system that carries out the instructions of a computer program, to perform the basic arithmetical, logical, and input/output operations of the system. The CPU plays a role somewhat analogous to the brain in the computer. The term has been in...
, display
Computer display
A monitor or display is an electronic visual display for computers. The monitor comprises the display device, circuitry, and an enclosure...
, floppy disk drive and power supply
Power supply
A power supply is a device that supplies electrical energy to one or more electric loads. The term is most commonly applied to devices that convert one form of electrical energy to another, though it may also refer to devices that convert another form of energy to electrical energy...
all in a single briefcase-like enclosure. Similar in performance to the desktop computers of the era, they were easily transported and came with an attached keyboard that doubled as a protective cover when not in use. They could be used wherever space and an electrical outlet were available, as they had no battery.
The development of the laptop
Laptop
A laptop, also called a notebook, is a personal computer for mobile use. A laptop integrates most of the typical components of a desktop computer, including a display, a keyboard, a pointing device and speakers into a single unit...
form factor gave new impetus to portable computer development. Many early laptops were feature-limited in the interest of portability, requiring such mobility-limiting accessories as external floppy drives or clip-on trackball
Trackball
A trackball is a pointing device consisting of a ball held by a socket containing sensors to detect a rotation of the ball about two axes—like an upside-down mouse with an exposed protruding ball. The user rolls the ball with the thumb, fingers, or the palm of the hand to move a cursor...
pointing devices. The first laptop that could be used as an only computer was the PowerBook 500 series
PowerBook 500 series
The PowerBook 500 series was a range of Apple Macintosh PowerBook portable computers first introduced by Apple Computer with the 540c model on 16 May 1994...
; with its built in Ethernet, video, SCSI, ADB and serial ports, it duplicated the functionality of the desktop models without requiring an external docking station
Docking station
A Docking station or port replicator or dock provides a simplified way of “plugging-in” an electronic device such as a laptop computer to common peripherals...
.
The development of the modern desktop replacement computer came with the realization that many laptops were used in a semi-permanent location, often remaining connected to an external power source at all times. This suggested that a market existed for a laptop-style computer that would take advantage of the user's reduced need for portability, allowing for higher-performance components, greater expandability, and higher-quality displays. Desktop replacement computers are also often used with a port replicator, to fully enjoy the desktop comfort.
Design features
Modern desktop replacements generally perform better than traditional laptop-style computers as their size allows the inclusion of more powerful components. The larger body means more efficient heat-dissipation, allowing manufacturers to use components that would otherwise overheat during normal use. Furthermore, their increased size allows for greater expandability and features, as well as larger and brighter displays. However, these advantages generally come at a price premium, with many computers in this class costing as much as two desktop computers with similar specifications.Using a laptop form factor, however, desktop replacements still often suffer from limitations similar to those of more mobile laptops. They usually lack the ability to accept standard PCIe
PCI Express
PCI Express , officially abbreviated as PCIe, is a computer expansion card standard designed to replace the older PCI, PCI-X, and AGP bus standards...
expansion cards, limiting their expandability somewhat. While desktop replacements can offer better cooling than other laptops, they rarely dissipate heat efficiently enough to allow for high-end desktop-class components, and thus may not reach the same performance levels as desktop computer
Desktop computer
A desktop computer is a personal computer in a form intended for regular use at a single location, as opposed to a mobile laptop or portable computer. Early desktop computers are designed to lay flat on the desk, while modern towers stand upright...
s.
Desktop replacement computers are, with a few exceptions, difficult to upgrade compared to desktop computers, with many of their major components (such as the display) integral to the design of the machine, and others (such as the CPU and GPU) often being hard to access and replace.
A small segment of desktop replacements do not include a battery as a standard feature, while some do not include ExpressCard
ExpressCard
ExpressCard is an interface to allow peripheral devices to be connected to a computer, usually a laptop computer. Formerly called NEWCARD, the ExpressCard standard specifies the design of slots built into the computer and of cards which can be inserted into ExpressCard slots. The cards contain...
support. They have the same limitations on serviceability as laptops, and can rarely use identical components to a desktop computer.