The ‘Universal Interface for Windows’ designed by Burkhard Kainka (Elektor Electronics, December 1999 Supplement, page S2) provides for a range of input interfaces along with eight digital outputs, all under direct control of a PC’s serial port. The program (available for free download from http://www.elektor-electronics.co.uk under ‘Magazine’) uses the TXD signal to clock eight data bits from the DTR signal into a 4094 shift register.