dyer@halleys.UUCP (Steve Dyer) (10/30/86)
A few questions: is the Q-bus DMV-11 equivalent to the Unibus DMR-11? - will they interoperate (will a DMV-11 talk to a DMR-11?) - is the DMV-11 program-compatible with the DMR-11? (i.e. under Ultrix, will it use the BSD dmc driver?) How many DMR-11's can be installed on a single VAX? How many DMV-11's can be installed on a single MicroVAX? I see no hard-limit in the dmc driver, although there may be an implicit limit due to resources like Unibus mapping resisters. Are there power- consumption issues which would limit their number? -- --- Steve Dyer spdcc!dyer dyer@harvard.harvard.edu
johnsson@decwrl.DEC.COM (Richard Johnsson) (11/06/86)
> is the Q-bus DMV-11 equivalent to the Unibus DMR-11? sort of. They are similar. The DMR is much more general and can go up to 1 megabit per second. The DMV is limited to 56K. For most normal purposes ther are functionally equivalent. > will they interoperate (will a DMV-11 talk to a DMR-11?) Yes. They both speak DDCMP (version 4 I believe). We have many talking to DMR's in the internal DEC network (all DECnet based). We haven't yet tried any in Ultrix. > is the DMV-11 program-compatible with the DMR-11? Not quite. I don't know the differences, but I have looked at the source for the DMV driver in Ultrix 2.0 and it says it was derived from the dmc/dmr driver. It is apparently different enough that putting in a few runtime conditionals was not reasonable. > How many DMR-11's can be installed on a single VAX? Mostly I think it depends on having enough Unibus power. They suck up a lot of +5 (about the same as a UDA50 which is about 12 amps for the two boards). I believe the power requirement limits you to four per BA11 box. Locally we have a VMS 750 in the internal network with 6 DMR's (4 @ 9.6 and 2 @ 56). We have an Ultrix 750 with 4 DMR's (2 each 9.6 and 56). > How many DMV-11's can be installed on a single MicroVAX? Our newly installed DECnet router microvaxen each have 5 DMV's. Corporate Telecom which runs the internal network approves of running one DEQNA and 5 DMV's @ 56K on a microvax (II of course :-) as a dedicated router. > I see no hard-limit in the dmc driver... Actually there's a bug in the Ultrix 1.2 dmc driver (which may have been propagated from or to elsewhere) which limits it to one: At line 389 (first executable line of dmcload()) change unit = (sc - dmc_softc)/ sizeof (struct dmc_softc); to unit = (sc - dmc_softc); Also there are some funnies in the handling of multiple point-to-point links (and point-to-point links in general) in Ultrix 1.2, BSD 4.2 and at least early versions of 4.3. I have sent the changes to be included in Ultrix 2.0 but haven't looked lately to see if they're in. Hope this helps. -- Richard Johnsson, DEC Western Software Lab, Palo Alto, CA UUCP: {decvax,ucbvax}!decwrl!johnsson ARPA: johnsson@decwrl.dec.com DEC ENet: rhea::johnsson phone: +1 415 853 6676