Xref: utzoo comp.realtime:5 comp.os.vms:14108
Path: utzoo!utgpu!jarvis.csri.toronto.edu!mailrus!csd4.milw.wisc.edu!lll-winken!uunet!philmtl!philabs!ttidca!kevin
From: kevin@ttidca.TTI.COM (Kevin Carothers)
Newsgroups: comp.realtime,comp.os.vms
Subject: Streaming tape drives
Message-ID: <4374@ttidca.TTI.COM>
Date: 5 May 89 20:29:48 GMT
Organization: Citicorp/TTI, Santa Monica
Lines: 29


Greetings

This is a rather whimsical question, but I would like an answer.

I used to work for a company that made a data-acquisition front-end
to a DEC PDP-11/73 (Cyber systems, Anaheim).  At the time, we had a 
requirement to write 50Kwords/sec to a Cipher (tm) 9-track streamer tape
under the RSX O/S.

Well, we never made it. The best we did was maybe 35Kwords/Sec.
The tape drive never went into "streaming" mode, and  we all just 
kind of gave up.

Does anyone out there know if this is even possible? We tried every
conceivable buffering size, I/O mode, double-buffering schemes, etc.
RSX is very (ok, somewhat) similar to VMS in philosophy (ie; DCL), and 
the PDP and VAX have similar Command/Status/DMA register structure, so it 
seems like *someone* in the VAX/realtime world would have come across this 
problem before.

BTW --
Anyone out there use Cyber Systems data acquisition equipment? 
If so, what model(s), and any gossip about how they are/were doing?


Just curious
=========================================================================
Kevin Carothers   !{csun,psivax,rdlvax}!ttidca!kevin