[comp.os.vms] Terminal baud rates and system throughput

DNEIMAN@carleton.EDU (04/17/87)

We have an 11/780 with approximately 48 Emulex DMF-32 emulation terminal
ports.  What is the effect on overall throughput of allowing users to
connect to the VAX with terminals set to 9600 baud?  Our current rate
is between 2400 baud and 4800 baud, with few 1200 bauds.

This used to be an issue when we were using DZ's; with DMF-32's is the
story any different?

LEICHTER-JERRY@YALE.ARPA.UUCP (04/18/87)

    We have an 11/780 with approximately 48 Emulex DMF-32 emulation terminal
    ports.  What is the effect on overall throughput of allowing users to
    connect to the VAX with terminals set to 9600 baud?  Our current rate
    is between 2400 baud and 4800 baud, with few 1200 bauds.

    This used to be an issue when we were using DZ's; with DMF-32's is the
    story any different?

DZ's an interrupt on every character going in or out.  DMF's are able to do
DMA output.  The result is much less system overhead.  It's hard to be sure
without trying it, but I suspect you'll have few if any problems running at
9600 baud.
							-- Jerry
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taso@munnari.UUCP (04/18/87)

I recently had occasion to work at a site where virtually all
terminals where connected through MUXServers.  The system manager(s)
held the baud rate on these terminals down to 4800 `in the interests of
system performance'.  Apart from any discouraging effect that the low baud
rate might have on a terminal user contemplating whether she should refresh
her screen or not, what are the technical merits of the low baud rate
policy?  (Interestingly, the few directly connected terminals were run at
9600 baud or higher).