Manualy Sending Info to the Serial Port

Hello Folks

I have a G3 B&W and a Pismo and I was wondering how to manually send info to the serial port? Let me Clarify, I want to send ASCII characters to a microcontroller via a Keyspan USB to Mini Din 8 Serial adapter. Most (we will say all) Microcontrollers are RS232 or USB and I wanted to do this with actually an old 68K Mac,(Workbench Space and I love the old 68K's) which has mini din 8's natively but I wanted to do it w/PPC first because I don't own an old 68K yet. I cant find any terminal programs and A/UX only works with specified 68K's. Not doing this in OS X. Mac OS 9. I know there is a Hypercard Serial Port Toolkit but I have yet to find it. Any help would great! There is a personal reason for not using Mac OS X so please hold the comments about it, it would be much apreciated.