Path: utzoo!utgpu!tmsoft!mcl!unibase!root From: root@unibase.UUCP (Super User) Newsgroups: comp.sources.d Subject: Re: Remote control of PC via modem Message-ID: <104@unibase.UUCP> Date: 3 Dec 88 09:52:56 GMT References: <4652@phoenix.Princeton.EDU> Organization: EMIS Consulting, Regina, Saskatchewan, Canada Lines: 52 From article <4652@phoenix.Princeton.EDU>, by mfryba@phoenix.Princeton.EDU (Martin Francis Ryba): > > I want to remotely control a AT via the modem port. I don't want the > graphics (just tty), so I can do this from any machine. etc. No communication software of any kind is required for this kind of control. Assuming that you want to run standard software (ie: it calls the standard MS-DOS calls for input and output), commands exist within MS-DOS that will permit control to be passed to a communication port. The basis of the solution is the 'ctty' command, which shifts the command input/output from the keyboard/screen to a com port. The problem is that the cable required between the modem and the computer has to be jumpered all over the place. I can't remember the cable I wound up using; solve the problem with a breakout box and a pile of jumpers. Best approach is: take a PC and a terminal (ignore the modem for now), and get the PC to the point that these commands: mode com1: 1200,n,8,1 ctty com1: will give control to the terminal. DON'T DESPAIR!!! It can be done with the right jumpers on the cable. If I remember correctly, simple jumpering on the PC end does not work, because the ctty command does not cause the PC to assert anything at all on its' com port. Find a pin on the terminal that is asserted when it's on, and connect it to 4,5,6,8, and 20 on the PC end (this is a guaranteed jump - no matter what mode - DTE or DCE - the PC uses). HINT: the PC transmits data on pin 2. Most terminals transmit on pin 2 as well, so you will need to invert 2 & 3. Connect pin 7 to 7. Once you have that working, try this for a modem connection: set the modem for carrier detect on only when connected; set the modem to ignore DTR, and answer on the first ring; connect 4,5,6 8 and 20 on the PC to 8 on the modem; connect 2 to 2, 3 to 3, and 7 to 7; And give it a try. The nice thing about the ctty solution is that it works very well with all software that follows the ms-dos convention for character input/ output. NB: screen-based programs that address video ram directly will NOT function with this solution - however, you can edit with edlin, copy, start other comm programs, etc.. ALL ms-dos commands function. Good luck.