Expansion Bus - History

History

The first kit-built microcomputers used a bus design called the S-100 bus 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 IBM 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.