I've got a problem I've found to be quite difficult to solve. Recently I bought an old UNIX machine from the late eighties, a DIAB1100 with a Motorola 68K processor. I've used Linux for a while now, so I know the basics of that OS and thought it would be interesting to see a real UNIX in action.
I planned on using one of my PC's as a terminal but this is where it gets difficult. I have a null modem cable hooked up between the computers. I'm using Minicom om my PC, set to 9600 baud, 8-N-1 (the seller thought that those would be the correct settings).
I can't establish a connection at all, the Minicom status is "offline". Could anyone here give some advice or hints? I would really like to access this piece of hardware.
Try using hyperterminal. Or if you can configure minicom better, do that. It sould like minicom is looking for dsr or dcd from the modem. But you don't have a modem. You want to configure it hard-wired or direct connect or something like that. 9600 8-none-1 is probably right.
Thanks for the input. I haven't thought about the dcd/dsr thing, but I have used the PC in question as a serial terminal when hooked up to another PC running agetty quite recently. Doesn't that mean that dcd/dsr shouldn't be an issue in this case?
I noticed another thing just now, the UNIX machine has several "CS" lights. Is this some type of "Clear to Send" indicator? You see, the "CS" light above the DB9 port (male) where I've plugged my null modem cable in isn't lit, which worries me a bit. Instead, the "CS" light goes on first on the Ethernet card (a BNC connector type, so I have no way of hooking anything up that way) and then on something that looks like a 50-pin SCSI port (female). After maybe 30 seconds, the light changes to the Ethernet card again and then it keeps changing between the two repeatedly until I turn it off.
I'm new to the concept of hardware terminals, but is it possible that the VT100 terminal was in fact plugged in on the SCSI-port?
EDIT; I took a closer look at the Ethernet card again. There's a 15-pin female port underneath the BNC port. Could perhaps that be where the terminal was plugged in?
Yup, that's the one I bought. There's one DB-9 port on it but no DB-25.
These are the connectors, left to right;
2 x 15-pin connectors
1 x 37 pin connector
1 x BNC connector (thin internet)
1 x 15 pin connector (thick ethernet)
1 x 50 pin connector (SCSI?)
1 x 9 pin connector (DB-9)
I'm not sure exactly what the AUT/MAN switch does either. Does anyone know what the CS lights mean? They can be clearly seen in the picture. As I explained in the above post, the only ones of those that are lit are the one on the Ethernet card and the one above the 50-pin port right of the Ethernet card. Those two are never lit simultaneously, instead they "take turns" being lit with what seems to be regular intervals. First the Ethernet light is on for one minute and then it switches to the other one for perhaps three seconds, after that one minute Ethernet, and so on. Does it matter that the CS light above the DB-9 port is always off?
EDIT;
Some more info; I did some reading up on flow control and now I think I understand what the lights above the DB-9 port (except the "CS" one) mean. Above the DB-9, but below the "CS" light are five indicators, listed (top to bottom) +12V, +5VH, +5V, +5VL, -12V. Of these, +12V, +5V and -12V are lit (green). The others are not lit. I assume this is linked to the flow control but I don't know how to use that knowledge yet. I've tried experimenting with gtkterm, but the only thing that happens is that I can get gtkterm to crash occasionally and on other occasions get "input/output error" on the console used to launch gtkterm.
You can just try removing the cable from Unix machine and connect pins 2 and 3 and see if you see echo of characters as you type in on your PC. But be careful while doing that, otherwise you end up damaging the serial port.
Connections will be different if you have 25pin connector on your PC, not the case usually, unless you have a very old machine