English: IBM PC Motherboard from 1981. The IBM Personal Computer Model 5150 was the first computer of the type which is today (2023) generically known as a "PC". It had an Intel 8088 microprocessor with 4,77 MHz, five bus connector ports for expansion cards (ISA Bus, 8 Bit) and 16 KB to 64 KB RAM on the motherboard - installed on the pic are 32 integrated circuits (4x8 ICs below right) of the type AMD Am9016 with 16,384 Bits each (2 kByte), resulting in the RAM having the maximum installable size of 64 kByte. The additional 9th row separately below is most likely for parity checking (error control).