AT is basically a form factor of a computer motherboard, it officially stands for Advanced technology. This has an exactly similar configuration and design structure as the original baby-AT form factor that was used in the IBM PC (IBM compatible personal computers), the configuration; 12 x 13”.
The AT form factor of the motherboard was the actual predecessor of the Baby-AT motherboard configuration. The Baby -AT motherboards are made a bit tiny in terms of their size and design with a normally smaller dimensional configuration of 8.5” to 13”. Similar to the IBM’s PC and IBM XT variants before the Baby-AT, that many computer and PC companies, manufactured and introduce MOBOs that were compatible with the IBM’s AT form-factor which enables the users to improve their PC’s usability and fast working experience.
The AT motherboard is also cited as Full-Sized AT, just like the Baby-AT form factor of the motherboard the Full-Sized AT was also developed by IBM In the mid of the year 1980. It can only fix into a complete size tower case only, the AT motherboard was earlier considered a scarce product, and its availability was considered as rare.
But now the scene has changed a lot, where the AT form factor has been replaced by the current-gen modern era ATX form-factor of the motherboard and the Baby-AT motherboard.
The IBM’s AT motherboard’s design was used by other companies with the intention of copying its design when it was at its peak of market spread during the decade 1980. Many small ventures tried their best to copy it but couldn’t give out the exact same model with the same set of features and they ended up making the first copy and clone designs of the AT motherboard which also impacted its popularity in the 1990s.
From the commencement of the year 1995 the AT motherboard was superseded by the new ATX motherboard.