http://groups.google.com/groups?hl=en&lr=lang_en&ie=UTF-8&threadm=c0kvrk%2418et7k%241%40ID-56855.news.uni-berlin.de&rnum=30&prev=/groups%3Fq%3Dchrony%2Bprogram%2B-clock%26num%3D100%26hl%3Den%26lr%3Dlang_en%26ie%3DUTF-8%26filter%3D0
I also found a reference to a free program QBALL ver 3.00 that connects using msdos interface. But I can't search out that program. I assume that it uses the serial interface with (25 pin conn) pin 3 as receive and pins 4 and 5 (request to send and clear to send) shorted together so that the port free runs.
Gregory