("Advanced Technology") A version of the IBM PC, released in Aug 1984 with an Intel 80286 processor, a 16-bit bus, a medium-speed hard disk and a 1.2 megabyte floppy disk drive. It had a larger case than the PC, which allowed it to accept "tall cards". The AT keyboard corrected the PC's non-standard placement of the return and left shift keys but shortened the backspace key, making it harder to reach.