Sellam, this might be an obvious question, but does the EI have the serial port option board installed? There is a plastic cover that's held down by two screws (I _think_) on the top of the EI that covers the little serial board. If it _is_ installed and it hasn't been modified, it would be a good idea to pull it and clean the connectors on both the serial board and the EI since they're just a pressure fit with no real connector. The edge connector is the serial port. There is also an edge connector that brings out the parallel port lines. You can figure out which is which by tracing the lines on the board. I'm pretty sure the serial connector comes out the left side as you face the EI. g. On Thu, 18 Jan 2001, Vintage Computer Festival wrote:

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 * *