SERPORT.TXT- By KG. Detecting Serial and Parallel Ports with DEBUG ----------------------------------------------- If you cannot tell which ports (parallel and serial) the computer is using, check for the I/O ports using the DOS program DEBUG Follow the steps to use DEBUG: 1. Run DEBUG 2. At the DEBUG prompt, type D 40:0 and press Enter. This step displays the hexadecimal values of the active I/O port addresses, first serial and then parallel. Example display: 0040:0000 F8 03 00 00 00 00 00 00- BC 03 00 00 ... com1 com2 com3 com4 lpt1 lpt2 ... The address for each port is shown in the corresponding position. Because addresses are stored as words, the byte values are swapped and should be read backward. This example indicates one serial port installed at 03F8 and one parallel port installed at 03BC. 3. To exit DEBUG, press Q and press Enter. 9 Pin (AT) Serial Port Connecter --------------------------------- Pin Description Signal Direction 1 Carrier detect CD In 2 Receive data RD In 3 Transmit data TD Out 4 Data Terminal Ready DTR Out 5 Signal ground SG - 6 Data set ready DSR In 7 Request to send RTS Out 8 Clear to send CTS In 9 Ring indicator RI In 25 Pin (PC, XT, and PS/2) Serial Port Connecter ------------------------------------------------ Pin Description Signal Direction 1 Chassis ground - - 2 Transmit data TD Out 3 Receive data RD In 4 Request to send RTS Out 5 Clear to send CTS In 6 Data set ready DSR In 7 Signal ground SG - 8 Carrier detect CD In 9 (+) Transmit Current Loop Return - Out 11 (-) Transmit Current Loop Data - Out 18 (+) Receive Current Loop Data - In 20 Data terminal ready DTR Out 22 Ring indicator DI In 25 (-) Receive Current Loop Return - In