yang1@ntvax.UUCP (cqyang class) (06/02/89)
We may have beat this to death already but... Is there anyone out there that has used an AT&T 3B20D minicomputer? As I understand, this machine has a writable microcode section in it. It is used by the telephone company to run with its 5ESS phone switching machines. The reason it has a writable microcode section is so the machine can run programs written for processors in provious switching machines. It also has a permanent copy of the 3B instruction set to run 3B software. The other instruction sets are loaded in when the machines boots. When running with the 5ESS, it uses an operating system called DMERT. The computer system can also be used as a reliable stand alone minicomputer. It has two processor boards. It constantly monitors itself to check for faults. When one is detected, a second processor board takes over, signals a fault, then takes off where the first processor left. The faulty processor board, or any other type of board that needs to be replaced, can be done while the machine is still running. Software upgrades can also be done while the machine runs. ******************************************************************************* * "It is most gratifying that your enthusiasm for * * Jim Stinson our planet continues unabated and so we would * * University of North Texas like to assure you that the guided missiles * * yang1@dept.csci.unt.edu currently converging on your ship are part of a * * special service we extend to all of our most * * Warning to the enthusiastic clients, and the fully armed * * 'Heart of Gold' crew, nuclear warheads are of course merely a courtesy * * "The Hitchhiker's Guide detail. We look forward to your custom in future * * to the Galaxy" lives. Thank you." * *******************************************************************************
snoopy@sopwith.UUCP (Snoopy) (06/05/89)
In article <483@ntvax.UUCP> yang1@ntvax.UUCP (cqyang class) writes: | Is there anyone out there that has used an AT&T 3B20D minicomputer? Yes. Don't remind me. | It is used by the telephone company to run with its 5ESS phone switching | machines. Yes. The Duplex feature is very important for such high-rel applications. | When running with the 5ESS, it uses an operating system called DMERT. Duplex-<something>-Executive-Real-Time. Something like that. I believe they changed the name to UNIX RTR a few years ago. | The computer system can also be used as a reliable stand alone | minicomputer. It has two processor boards. Two boards? More like two racks-full. A lot of the boards had their own local micro (8085/8086/2911/etc) to do whatever. A processor full of processors. (This was before divestiture, so you couldn't call it a "computer".) | It constantly monitors itself to check for faults. When one | is detected, a second processor board takes over, signals a fault, then takes | off where the first processor left. The faulty processor board, or any | other type of board that needs to be replaced, can be done while the machine | is still running. It also runs off of 48VDC batteries which are constantly trickle-charged. If commercial power goes away the diesel generator is supposed to start up before the batteries die. Anything requiring AC (fans, disks) runs off an inverter. These inverters make for some great war stories. *grin* | Software upgrades can also be done while the machine runs. Of course! You don't want to pull the plug on thousands of phone calls just to install a bugfix or the latest speed-forwarding feature, do you? And you can back them out again if you decide the cure is worse than the disease. _____ .-----. /_____\ Snoopy ./ RIP \. /_______\ qiclab!sopwith!snoopy | | |___| parsely!sopwith!snoopy | tekecs | |___| sun!nosun!illian!sopwith!snoopy |_________| "I *was* the next man!" -Indy