Computer Circuit

I got a problem with my notebook, because it has only COM1. My programmer board, Easy-Downloader must use serial port and the application board also needs to communicate via the same serial port. I do remembered I have to swap DB9 connector of both devices many times. So I spent 30 minutes built above simple hardware. Of course it was not the expander by meaning. But it helps me a lot. Someone may prefer to call it as the rs232 selector, but I like "expander". Above picture is the sample board, no need to make a pcb...

This circuit is a modified version of an original interface on QSL Net. It is a fully isolated interface allowing computer control of the Trio/Kenwood R5000 receiver. Separate software is needed to control the receiver...