terminal communications question

[Henry Spencer]

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