IBM Personal Computer/AT

Please note that the content of this book primarily consists of articles
available from Wikipedia or other free sources online. The IBM Personal
Computer/AT, more commonly known as the IBM AT and also sometimes called
the PC AT or PC/AT, was IBM's second-generation PC, designed around the
6 MHz Intel 80286 microprocessor and released in 1984 as machine type
5170. The name AT stood for "Advanced Technology", and was chosen
because the AT offered various technologies that were then new in
personal computers; one such advancement was that the 80286 processor
supported protected mode. IBM later released an 8 MHz version of the AT.