AT (form factor)

  • AT Baby -AT
  • Mini -ATX
  • Micro -ATX
  • FlexATX
  • Mini - DTX
  • Mini -ITX
  • Nano-ITX
  • Pico -ITX

The AT- format (English advanced technology " advanced technology ") is a form factor for housing and motherboards IBM PC - compatible personal computers. The AT form factor is the predecessor of the ATX form factor and the successor to the XT- format (English extended technology). XT- and AT- format developed by IBM.

Was introduced this format with the IBM PC AT.

Under the form factor is defined as a standard of the size of the motherboard, hole spacing up to standards of the power supply. The position of the components is thereby determined.

There are the normal AT- format, and the resulting bit later Baby AT format ( BAT). BAT is more compact in shape, but fits into the same housing.

The computer of the AT class became known by the 80286 processor from Intel (or its successor 80386, 80486, Pentium, ...) and by 16 -bit ISA slots for expansion cards. The 16- bit ISA bus is therefore often called AT bus, the 8-bit ISA bus called XT bus.

Motherboards in the AT or BAT format also exist with slots for other bus systems. Usual, the combinations 16 -bit ISA slots VLB slots, 16 -bit ISA slots PCI slots ( i486 the last generation and later ), and as the last representatives of their type slot-1 and Super -socket 7 motherboards with 16 -bit ISA slots PCI slots AGP slot. Also in AT format were available motherboards with Extended ISA slots.

The switch of the AT case was directly in the 127 - or 230 - V supply cable of the power supply looped and not connected as in the ATX form factor, with the motherboard. Therefore, the computer could not be activated by software on or off. The device measures for, unlike today's PCs, in the off-state no current. A software-controlled standby mode still was possible, but was common until the introduction of the APM power-saving standard, which was only introduced to the ATX - time. Before there were computers at AT proprietary Standby-/Suspend-to-RAM-Modi, some with their own stand-by button on the AT- housing. The wake from sleep / soft-off by PCI card, however, was only introduced with ATX1.0 until today but almost never realized in practice.

In the first PCs of the power switch was located at the rear or rear side directly on the power supply. For subsequent housing types he was attached for convenience on the front page. For an AC voltage had to be passed transversely through the PC case and often also grounded to the front leading cable. The cables and switches used for this purpose, however, were not in the electrical wiring still in the mechanical design standardized, making it difficult to replace the power supply.

  • Standard (hardware)
  • Circuit board