homebrew8088 The clock is what makes your 8088 run, with out a properly functioning clock nothing works right. You need to select the crystal based on the processor you chose to use. The mHz of the crystal is divide by three and output on the CLK pin. The maximun rating is 5mHz for the 8088, and 8mHz for the 8088-2. Build your own 8088 Microprocessor kit - kswichit Hardware schematic (click to enlarge) Hardware descriptions: U5 is CMOS 80C88 microprocessor in minimum mode. The Address bus is demultiplexed with ALE signal and latched by U6 and U9, 74HC573.