I used to use 3B1 and 7300 systems quite a bit. There was a CUI/GUI system called MGR, and they served quite well as UUCP mail-enabled workstations. Motorola 68k based. However, everything from the 3B2 on up was based on the Western Electric 32000-series processors. The Regional Bell's original Operations and Support Systems were largely PDP-11/45 and PDP-11/70 minis. These were transitioned for the most part to AT&T 3B20S ("Simplex" processor) servers towards the late 80's, the internal OSS applications these machines ran being designed by Bellcore. The RT version you're referring to is the AT&T 3B20D ("Duplex processor), which served as the processing core of the AT&T 5ESS (Electronic Switching System), at one time one of the two most powerful digital switching systems in the telephony world. The original real-time Unix developed for this platform (by AT&T) was called DMERT, for Duplex Multi Environment Real Time. This ultimately evolved into the 5E-2000 switch, with the OS evolving into AT&T UNIX RTR (Real Time Reliable). Not DECnet capable. The standard hard-wired networking method was AT&T Datakit VCS (Virtual Circuit System). Telenet X.25 hardware was also a common networking interface. By the way, I'm also from Queens. -Mark On Wed, Nov 28, 2012 at 7:19 AM, Gregg Levine <gregg.drwho8 at gmail.com> wrote: On Wed, Nov 28, 2012 at 9:20 AM, Dave McGuire <mcguire at neurotica.com> wrote: On 11/27/2012 10:25 PM, Boyanich, Alastair wrote: Wasn't there some bitsliced cpu variants ? Of the 7300/3B1? No, not that I'm aware of. They're call 68010-based. I know there was the AT&T UNIX PC which was a 68010 + custom external MMU, but there was also a proprietry cpu version I ran into the trap of in a past life. The "UNIX PC" is the 7300, which is nearly identical to the 3B1. The 3B1 has a slightly larger top cover to accommodate a full-height hard drive, while the 7300 will only hold a half-height drive. They are otherwise identical, using 68010s. I'd sure like to know more about the "proprietary cpu" version you're talking about. -Dave -- Dave McGuire, AK4HZ New Kensington, PA Hello! He's thinking of the WE designed processors that were used in the later units. They were not bit slice but were fabricated using the normal methods. Not surprisingly enough the devices could not even be sold separately. They were ran an appropriately written release of UNIX as native. One of the first applications for them and the later models was in running the first and second generation Electronic Switching Services otherwise known as exchanges. There's a whole article online someplace on the RT extensions that needed to be written out and added to UNIX for that application. ----- Gregg C Levine gregg.drwho8 at gmail.com "This signature fought the Time Wars, time and again."