Well, there is no RS-232C port with the basic interface. This requires a card to be installed in the bay on top of the interface. If you have this card installed, the signals appear at the "Expansion Board Card Edge" which is in the middle of the front of the interface. The card edge is 40 pin. The following are the main signals an pins: 18-TD; 20-SGND; 22-RD; 30-CD; 32-CTS; 34-DTR; 36-RTS; 38-RI; 40-DSR. Louis On Thu, 18 Jan 2001 10:21:23 -0800 (PST), Vintage Computer Festival wrote: * *I need to know where the serial port connector is on a TRS-80 Expansion *Interface. I have two of them. One has its ports labeled, and one of the *ports is labeled "MODEM" but it is simply an edge connector. Is this the *serial port? If so, what's the pinout? * *Any help would be greatly appreciated. Thanks! * *Sellam Ismail Vintage Computer Festival *----------------------------------------------------------------------- ------- *International Man of Intrigue and Danger http://www.vintage.org * *