Copyright © Anne Watson
In 1981, IBM released the original personal computer.
The original motherboard had five expansion slots which were very much like ISA (Industry Standard Architecture) slots. The data path for these slots was 8 bits wide. This means that the bus could only handle 8 bits of information at a time.
These motherboards could only support between 64KB (KiloBytes) and 256KB.
At the back of the board were two connectors -
In 1983, the eXtended Technology computer was released. These had three extra expansion slots and the cassette connector began to be replaced by floppy drives and eventually hard drives.
The primary memory capacity was increased to 640KB.
In 1984, IBM released the Advanced Technology (AT) ‘form factor’. The AT used a 16 bit data path and the ISA slots were modified to take this into account.
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