ravi@maui.cs.ucla.edu (T.M Ravi) (05/04/90)
I am looking for information on DEC's Mass Storage Control Protocol (MSCP), and their Mass Storage Subsystem. I am interested in how they provide a logical interface which is device independent. Any information related to this or pointers on how to obtain it would be appreciated. Thanks T. M. Ravi ravi@cs.ucla.edu ravi@iag.hp.com
ckp@grebyn.com (Checkpoint Technologies) (05/05/90)
In article <34955@shemp.CS.UCLA.EDU> ravi@maui.cs.ucla.edu (T.M Ravi) writes: > >I am looking for information on DEC's Mass Storage Control Protocol (MSCP), >and their Mass Storage Subsystem. I am interested in how they provide a >logical interface which is device independent. Any information related to this >or pointers on how to obtain it would be appreciated. I've read the MSCP protocol documents and have written an MSCP disk driver (for a custom OS); however, that was a few years ago so all the details are foggy. I can't say much about anything besides the CPU's programming model for MSCP. Being device independent is pretty simple. SCSI does that too. The device is expected to appear as a linear array of 512-byte sectors numbered from 0 to the size of the device. The CPU knows nothing about tracks or cylinders, though with a command it can find out. The IO space contains a big total of two registers, the SA and the IP registers. The bulk of communications between the CPU and MSCP is via a communication region in memory. The CPU builds a request packet, "touches" the IP register to indicate there's a command; the MSCP interface reads the command from memory, performs it, and writes a reply packet into a different area describing how the operation went. There can be several packets outstanding, and the MSCP device may seek-optimize them. You can get the MSCP specs from Digital, but I don't know how hard that might be. DEC has been getting very secretive about programing info for some of their hardware, especially MSCP and TMSCP (MSCP for tape); but that's really the best place to get the documents. -- First comes the logo: C H E C K P O I N T T E C H N O L O G I E S / / \\ / / Then, the disclaimer: All expressed opinions are, indeed, opinions. \ / o Now for the witty part: I'm pink, therefore, I'm spam! \/
dave@ecrcvax.UUCP (Dave Morton) (05/08/90)
>I am looking for information on DEC's Mass Storage Control Protocol (MSCP),
Good luck to you - it's patented and all DEC documents you
might want are out of print. I believe Chris Torek somehow
figured bits of it out.
--
Dave Morton, Systems Manager,
European Computer Industry Research Centre Tel. + (49) 89-92699-139
Arabellastr 17, 8000 Munich 81. West Germany. Fax. + (49) 89-92699-170
E-mail USA: dave%ecrc.de@pyramid.com EUROPE: dave@ecrc.deamw@cunixb.cc.columbia.edu (Andrew M. Winkler) (05/08/90)
If it's patented, it's a matter of public record :-)