Personal computer system with bus noise rejection

A personal computer system comprising:

• a local processor bus for passing data signals;
• a microprocessor operatively connected with said local processor bus for transfer of data signals through said local processor bus;
• an option bus for receiving option cards and for passing data signals to and from any option card received;
• a planar I/O bus for passing data signals;
• a bus controller operatively connected with said local processor bus and said option bus and said planar I/O bus for controlling passage of data signals between any two of said local processor bus and said option bus and said planar I/O bus to and from said microprocessor;
• and
• an I/O controller having a plurality of segments,
• a first one of said segments providing a serial port for exchange of data signals with said local processor bus,
• a second one of said segments providing a parallel port for exchange of data signals with said local processor bus, and
• a state machine for receiving external command signals passed on one of said busses and for passing internal command signals identifying valid data intervals, said state machine requiring a predetermined minimum length of external command signal for issuance of an internal command signal and terminating an internal command signal with termination of an external command signal so as to avoid any adverse effects of crosstalk and transmission line noise on external command signals and loss of data integrity thereby possibly occurring.