Expansion bus
Encyclopedia
An expansion bus is made up of electronic pathways which move information between the internal hardware of a computer system (including the CPU
and RAM) and peripheral devices. It is a collection of wires and protocols that allows for the expansion of a computer.http://www.webopedia.com/TERM/E/expansion_bus.html
for the number of pins on the connector. Many of these computers were passive backplane
designs.
Historically, IBM PC compatible
personal computers have used an expansion bus called the ISA bus
. ISA was supplanted by the PCI bus, which was in turn supplanted by the PCI Express
. For graphics cards, AGP replaced PCI and then migrated to PCI-express as well. There has been some talk of a new form factor for graphics cards that resembles a CPU socket. Users of the ISA bus had to have in depth knowledge of the hardware they were adding to properly connect the devices. However, the PCI bus made it much simpler, allowing for ease in assembly.
Personal computer architectures other than the PC used their own buses; the Apple Macintosh used NuBus
before switching to PCI and the Amiga
used Zorro II
and ISA. Both Zorro II and NuBus were plug and play, requiring no hardware configuration by the user.
Originally, the computer controlled the transfer of data, its efforts included interpreting, receiving, and sending out the data. Later on, a bus mastering
device was created. It essentially has the capability of controlling its own transfer of data to another device, allowing the computer to focus on other tasks. In essence this device freed up the computer, allowing for more efficiency.http://www.pccomputernotes.com/system_bus/bus02.htm
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...
and RAM) and peripheral devices. It is a collection of wires and protocols that allows for the expansion of a computer.http://www.webopedia.com/TERM/E/expansion_bus.html
History
The first kit-built microcomputers used a bus design called the S-100 busS-100 bus
The S-100 bus or Altair bus, IEEE696-1983 , was an early computer bus designed in 1974 as a part of the Altair 8800, generally considered today to be the first personal computer...
for the number of pins on the connector. Many of these computers were passive backplane
Backplane
A backplane is a group of connectors connected in parallel with each other, so that each pin of each connector is linked to the same relative pin of all the other connectors forming a computer bus. It is used as a backbone to connect several printed circuit boards together to make up a complete...
designs.
Historically, IBM PC compatible
IBM PC compatible
IBM PC compatible computers are those generally similar to the original IBM PC, XT, and AT. Such computers used to be referred to as PC clones, or IBM clones since they almost exactly duplicated all the significant features of the PC architecture, facilitated by various manufacturers' ability to...
personal computers have used an expansion bus called the ISA bus
Industry Standard Architecture
Industry Standard Architecture is a computer bus standard for IBM PC compatible computers introduced with the IBM Personal Computer to support its Intel 8088 microprocessor's 8-bit external data bus and extended to 16 bits for the IBM Personal Computer/AT's Intel 80286 processor...
. ISA was supplanted by the PCI bus, which was in turn supplanted by the PCI Express
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...
. For graphics cards, AGP replaced PCI and then migrated to PCI-express as well. There has been some talk of a new form factor for graphics cards that resembles a CPU socket. Users of the ISA bus had to have in depth knowledge of the hardware they were adding to properly connect the devices. However, the PCI bus made it much simpler, allowing for ease in assembly.
Personal computer architectures other than the PC used their own buses; the Apple Macintosh used NuBus
NuBus
NuBus is a 32-bit parallel computer bus, originally developed at MIT as a part of the NuMachine workstation project. The first complete implementation of the NuBus and the NuMachine was done by Western Digital for their NuMachine, and for the Lisp Machines Inc. LMI-Lambda. The NuBus was later...
before switching to PCI and the Amiga
Amiga
The Amiga is a family of personal computers that was sold by Commodore in the 1980s and 1990s. The first model was launched in 1985 as a high-end home computer and became popular for its graphical, audio and multi-tasking abilities...
used Zorro II
Zorro II
Zorro II is the name of the general purpose expansion bus used by the Amiga 2000 computer. The bus is mainly a buffered extension of the Motorola 68000 bus, with support for bus mastering DMA. The expansion slots use a 100-pin connector and the card form factor is the same as the IBM PC...
and ISA. Both Zorro II and NuBus were plug and play, requiring no hardware configuration by the user.
Originally, the computer controlled the transfer of data, its efforts included interpreting, receiving, and sending out the data. Later on, a bus mastering
Bus mastering
In computing, bus mastering is a feature supported by many bus architectures that enables a device connected to the bus to initiate transactions...
device was created. It essentially has the capability of controlling its own transfer of data to another device, allowing the computer to focus on other tasks. In essence this device freed up the computer, allowing for more efficiency.http://www.pccomputernotes.com/system_bus/bus02.htm
See also
- Bus (computing)
- Expansion cardExpansion cardThe expansion card in computing is a printed circuit board that can be inserted into an expansion slot of a computer motherboard or backplane to add functionality to a computer system via the expansion bus.One edge of the expansion card holds the contacts that fit exactly into the slot...
- List of computer bus interfaces