🚀 go-pugleaf

From article <13903@icarus>, by rickr@Semi.Mitel.COM (Rick Reitmaier):
> In article <C0z6r0.KGK@bunyip.cc.uq.oz.au> walker@s1.elec.uq.oz.au (Steven Walker) writes:
>>I have to write code that accesses memory mapped dual port RAM 
>>on a board connected to an AT bus. Any suggestions on how to do 
>>this in OS/2?
>>Do I need a device driver to allocate and lock the physical memory?
>>Or can I use IOPL levels to access it directly?
>>Thanks for any tips,

Well, this is your lucky day.  A month ago, I asked a similar question and
received enough information to write a generic device driver that I call
labhelp.sys.  You add it to your config.sys, and it implements a device
that lets any Ring 3 program access any physical block of memory, 
unprotected.  

This is clearly a form of unsafe sex.  It bypasses all OS/2 memory
protection and grants ANY protected mode application access to ANY 
physical block of memory.  I am using it currently for accessing memory
mapped A/D converters, and a memory mapped frame buffer.

The driver has been used under both CSET/2 programming and MSC 6.0.

I will make it available for anonymous FTP from 128.84.249.11
(lore.msc.cornell.edu).  Feel free to modify or use as you desire.
(I will make a LABHELP.ZIP file and hang it there tonight.)

> I don't know if or how it will work, but I would caution against building
> a device driver, as it's a grueling example of how evil an operating system
> can be to a programer.

But elegant once it is done!  In the end, it was quite simple.  Most of the
intelligence was put in the user shell running protected.
-- 
Michael O. Thompson            tommy@msc.cornell.edu
Cornell University             (607) 255-4714

OS/2:  For the few, the proud, the devoted!