AT to ATX Motherboard Card Extension
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The AT Form Card may not appear as a card at all, but translates the
header interface on a AT style Motherboard into an I/O connector. The AT Form Card may
appear as a Riser type card or a
connector/cable type arrangement. The AT form
factor motherboard did not define the I/O connectors as well as the
Baby-AT or ATX mother boards did. The ATX mother board defines the
location, placement and type of rear panel I/O, while the AT motherboard
did not. The AT motherboard was obsolete as off 1997 when the ATX mother
board was produced. So, by extension, the AT Form card is also obsolete
and no longer required by any new form factor mother board. There are a number of interfaces which exist on the AT motherboard which appear not to be taken to the case I/O. To gain access to these interfaces an AT Form Card is required. The motherboard contains a dual-in-line header which may be accessed, by the AT Form Card. The AT Form Card may consist of a board which plugs into the header and translates the I/O out the back panel, or a Header connector [to interface to the header on the motherboard]. |
The board solution is straight forward, connecting into the header and bringing connectors to the back panel, as a normal expansion card would. The IDC Header solution would translate to a ribbon cable which is then translated to connectors on the back-panel I/O. The back-panel I/O consists on the standard blank metal panel covering the I/O expansion slots at the rear of the computer. The connectors which are provided on the metal I/O panel include two USB connectors, a PS2 connector and an Infrared output. The AT motherboard header is a 2-pin [row] x 9-pin (18 pins) flat cable connector.
| Pin # | Signal Function | Pin # | Signal Function |
| 1 | USB +1 5vdc | 10 | Key Pin |
| 2 | USB +2 5vdc | 11 | Mouse Clock |
| 3 | USB -1 Data | 12 | Mouse Data |
| 4 | USB -2 Data | 13 | Ground |
| 5 | USB +1 Data | 14 | Ground |
| 6 | USB +2 Data | 15 | IR Hi |
| 7 | Ground | 15 | IR Input |
| 8 | Ground | 17 | IR, +5vdc |
| 9 | PS/2 +5vdc | 18 | IR Output |
Electronic Engineering Design Key words: Personal Computer Bus, PC Bus, Industry Standard Architecture Bus, Motherboard, Mother Board, AT Motherboard Bus, Backplane bus, ATX Motherboard Standard, Interface Standard, Specification, Spec, Electrical Interface, Parallel Bus, Physical Interface, Card Dimensions and Form Factors, Engineering Description, Component Manufacturers, OEM COTS, Connector, PinOut, Pin Out, Header, I/O Panel, Expansion slot.
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