hubert@entropy.UUCP (Steve Hubert) (06/15/84)
Would anyone care to discuss the relative merits of various terminal multiplexors. The good and bad points of DZ11's, DZ32's, DH11's, DMF32's, and so on. Thanks. Steve Hubert Dept. of Stat., U. of Wash, Seattle decvax!microsoft!uw-beaver!entropy!hubert hubert%entropy@uw-beaver
henry@utzoo.UUCP (Henry Spencer) (06/22/84)
To go quickly over the various Unibus terminal multiple-terminal interfaces: DZ11 One of the worst turkeys DEC has ever built. Various items of brain damage, but the worst is that there is no DMA, it's all one interrupt per character. This puts a dreadful load on your cpu if baud rates are high. The DZ11 can be made tolerable by using a KMC11 (a support processor that sits on the Unibus and handles the DZ11s for you) to do the character-by-character work. But KMC11s are a little bit magic, and not really cheap either. They are also abominable to program; consider this approach seriously only if you can get the programs for them from someone else, e.g. AT&T. DZ32 Same as DZ11, just a repackaging to get more lines on one Unibus board. DH11 Ancient DEC interface, not badly done but very old and huge. Probably not available any more from DEC. Said not to run on a VAX, definitely not supported by DEC on VAXen. DHDM DH11 lookalike from Able. Single Unibus board for 16 lines, full DH11 functionality. (Able also used to make a 3-board version; I *think* "DHDM" refers to the one-board one.) Runs just fine on VAXen. Lots of people use them. Good. CS11 DH11 lookalike from Emulex. Single Unibus board runs up to 64 lines, full DH11 functionality. All the per-line stuff is out in the distribution panels, which is why so many lines will fit on one board. This also means there is *one* small cable coming out of the board -- getting 64 lines any other way means a huge bundle of big flat cables coming out of your cpu box. Runs just fine on VAXen. A fair number of people use them. Excellent. (We use these.) CS21 Another DH11 lookalike from Emulex, pretty similar to the Able DHDM in functionality and packaging. Probably ok. DMF32 DEC's current "hot item" for terminal interfacing on VAXen. 8 lines on a Unibus board. Modem control on only 2. Some extra stuff on the board (line printer interface, misc) as well; the original motive for the DMF32 was that the 730 had very few peripheral slots in the cpu box, and putting together a decent system without an expander box required a board that had a little bit of everything. The design is new (*not* DH11 or DZ11 compatible) and there are various software problems because people don't know this thing as well as they knew the older designs. Supposed to be OK, but I don't know why you'd buy one unless you *must* have all-DEC hardware or you *must* have devices supported by a vanilla (gag) VMS. VMF32? Able has a DMF semi-lookalike with 16 lines on a board, full modem control (I think), and none of the miscellaneous extras. Said to be good, don't know much about it (not even sure of the designation). Same possible software headaches as DMF32. ??? Emulex has a version of their CS11 microprogrammed to look like DMF32s instead of DH11s. No info on it. Have I forgotten anything? Henry Spencer @ U of Toronto Zoology {allegra,ihnp4,linus,decvax}!utzoo!henry -- Henry Spencer @ U of Toronto Zoology {allegra,ihnp4,linus,decvax}!utzoo!henry