What are the bits for PC AT bus?

The PC AT bus, also known as the ISA (Industry Standard Architecture) bus, typically operates with a data bus width of 16 bits. It was originally designed for the IBM PC/AT and supports a maximum of 20 address lines, allowing access to 1 MB of memory. The bus facilitates communication between the CPU and peripheral devices, such as expansion cards and other hardware components. The ISA bus was widely used in personal computers during the late 1980s and early 1990s.