Path: utzoo!censor!isgtec!bmw
From: bmw@isgtec.UUCP (Bruce Walker)
Newsgroups: comp.sys.ibm.pc
Subject: Have Loadable Drivers Been Extended Since DOS 2.11?
Keywords: device driver
Message-ID: <112@isgtec.UUCP>
Date: 18 Jul 89 14:19:39 GMT
Reply-To: bmw@isgtec.UUCP (Bruce Walker)
Followup-To: comp.sys.ibm.pc
Distribution: na
Organization: I.S.G. Technologies, Toronto, Ontario
Lines: 27

I have been writing an MSDOS character-type loadable driver based on
the old MSDOS 2.11 manual section on "Writing Device Drivers".  This
driver properly requires an "open" and "close" call, which MSDOS 2.11
drivers don't support.

Just from curiosity, I dissassembled a driver that I had kicking
around, and I discovered that the driver header bit-word had an
"undocumented" bit set (bit 11).  I then discovered that the "command
decoder" part of the driver jumped on command numbers 13 and 14.
My 2.11 docs only list valid commands from 0 through 12.

Could this "new bit" mean "Extended Post-DOS 2.11 Driver"?

Could these extra commands be "open" and "close"?

Would someone please tell me:
1. whether my guesses are near the mark?
2. how to parse these extended commands

and/or:
3. what available docs could give me the answers to 1. and 2. above.

Thanks.
-- 
Bruce Walker                   ...uunet!mnetor!lsuc!isgtec!mutant!bmw
"Better Living Through Connectivity"  ...utzoo!lsuc!isgtec!mutant!bmw
ISG Technologies Inc. 3030 Orlando Dr. Mississauga. Ont. Can. L4V 1S8