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AT and Baby AT Motherboard

The AT and Baby AT motherboard were the most common form factor until 1997 when the ATX was introduced by Intel. The basic difference between the AT and the Baby AT is the width of the board.
AT and Baby AT Motherboard

The AT form factor is for the most part obsolete in today’s market. The 12″ wide AT had a few problems that lead to it being phased out. The size of the board meant it could only fit in a full tower case. The width of the board was large enough that it overlapped the drive bays making installation, upgrade, or repair allot more difficult. The AT was soon replaced by the Baby AT.

The Baby AT was introduced to correct some of these problems by cutting down the width of the motherboard to only 8.5″ wide. This solved the case problem, allowing the use of the smaller, more popular mid and mini tower cases. Also the smaller width took care of most of the overlapping of the drive bays. But changing the size of the motherboard led to some installation problems. The tendency on the newer versions of the Baby AT is that the 3rd row of mounting holes won’t line up with the case.

The AT and Baby AT motherboards worked well with the hardware of the time, but were not designed to handle the newer hardware. As processors have gotten faster and hotter, bigger heat sinks were needed to cool them. These two boards were not designed with cooling in mind as there was not a need for it when they were introduced. The lack of design and room for cooling sealed the AT and Baby AT’s fate.

The ATX form factors were developed to solve a lot of the cooling and other issues of the AT and Baby AT.