The PRO-350 used the F11 (Fonz) chip (same as in an 11/23). The PRO-380 used the J11 (Jaws) chip (same as an 11/73). Oh yeah - and RT-11 sure does run on them! We got it working on the PRO back in 1980... You should have seen some of the things we had to do to get it running, though... Some PRO strangeness - it has a 64hz clock... so, for RT-11 to emulate a 60hz clock, it counts 15 clock ticks and throws one away... :-) The PRO-380 doesn't have cache, but if you *turn off* the non-existent cache (using the cache control register), the machine slows down to 11/23 speed! Megan Gentry Former RT-11 Developer +--------------------------------+-------------------------------------+ | Megan Gentry, EMT/B, PP-ASEL | Internet (work): gentry!zk3.dec.com | | Unix Support Engineering Group | (home): mbg!world.std.com | | Compaq Computer Corporation | addresses need '@' in place of '!' | | 110 Spitbrook Rd. ZK03-2/T43 | URL: http://world.std.com/~mbg/ | | Nashua, NH 03062 | "pdp-11 programmer - some assembler | | (603) 884 1055 | required." - mbg | +--------------------------------+-------------------------------------+