dario@discus.technion.ac.il (Dario Ringach) (08/02/90)
Can anyone be kind enough as to explain me how can a mechanical mouse work when there is no Vcc pin assigned to the 9-pin D-connector on the IBM-PC serial interface? Thanks in advance for any help. --Dario. -- BITNET: dario@techunix | ARPANET: dario%techunix.bitnet@cunyvm.cuny.edu Domain: dario@techunix.technion.ac.il | UUCP: ...!psuvax1!techunix.bitnet!dario Dario Ringach, Technion, Israel Institute of Technology, Dept. of Electrical Engineering, Box 52, 32000 Haifa, Israel
robin@uhccux.uhcc.Hawaii.Edu (Robin Amano) (08/03/90)
In article <9759@discus.technion.ac.il> dario@discus.technion.ac.il (Dario Ringach) writes: >Can anyone be kind enough as to explain me how can a mechanical mouse >work when there is no Vcc pin assigned to the 9-pin D-connector on the >IBM-PC serial interface? Thanks in advance for any help. --Dario. > I don't know how a mouse is actually wired, but if it needs power it's probably getting power from pin 4 (DTR) or 7 (RTS). When you turn on a serial port or any terminal (in most cases) DTR/data terminal ready and RTS/request to send goes high, although I've seen some with only one of them high. It usually will stay high unless you are using hardware handshaking / ready busy. On a 9 pin 4 = DTR, 7 = RTS / on a 25 pin 20 = DTR, 4 = RTS. Also on some or at least most serial cards I've seen you can move around jumpers on the card to make certain pins high. You can check it with a volt meter, on a 9 pin 5 = gnd on a 25 pin 7 = gnd.