More 11/44 basic newbie help request

I thought it was silly too when I first laid eyes on such a system, but after some experience with it, I understand why. There may be other reasons as well, but here's my take on it. No one knew just what they or other folks were going to hang in these backplanes, or what functions those cards would perform. If they had known, it would have been pretty simple to provide a set of jumpers or some other (easier) means of moving signals around, but they didn't so they went for total flexibility in this department and so required jumper wiring. Some card slots don't carry certain signals over to the next slot down the line if there is no card installed in that slot. For example. If you have an hdd controller in slot A, a blank slot B, and a serial terminal controller in slot C, my machine wouldn't work at all. In this scenario, I would have to bridge the blank slot B by jumping two signals (IRQ and XSTL?) from A to C in order for those two critical signals to propagate past the blank slot. You might wonder why they would omit two of the most important lines With this method, you could have card's B and C connected via ribbon cable at their leading edges to carry the signal from B to C for use and then have card C propagate the signals over the backplane after they've served their purpose. You could even bring those signals outside the machine entirely to some specialized equipment before returning them to the backplane via a card. In this way, you could largely replace the backplane with your own custom wire job. Regards, Jeff -----Original Message----- From: cctalk-admin(a)classiccmp.org [mailto:cctalk-admin@classiccmp.org] On Behalf Of Jay West Sent: Tuesday, February 11, 2003 10:04 AM To: cctech(a)classiccmp.org Subject: More 11/44 basic newbie help request Eric wrote... You know... I think I've just been told "RTFM" *grin* S'ok, was well deserved :) After perusing the manuals for the 11/44 and the RL02's, and the RL11 (looking for docs on the 8 port mux now).... Most of my questions are answered there (big suprise). Not trying to start any holy wars or anything, but to my "newbie with unibus" mind, the design of having to change backplane wiring for certain cards seems to be rather... ummmm silly (euphamism{tm}), at least as compared to other systems of the period. Probably there is something I'm missing as to why this is a good thing. Jay West