roy@gitpyr.UUCP (Roy Mongiovi) (10/13/85)
Two programs that use undocumented features of DOS to display interesting
information about the PC environment have been posted to net.sources.
I believe that these programs run under PC DOS 2.0, 2.1, 3.0, and 3.1
(as well as the corresponding MS versions), but as with all undocumented
features: caveat programmer.
The first program, LDEVS, opens an FCB to the NUL: device and uses an
undocumented field of the FCB (which is different for DOS 2 and 3) to
find the start of the device chain. It then traces the chain displaying
the name and type of all devices.
The second program, MSCAN, uses an undocumented DOS function (52H - Get
In Vars) to find the first memory block, and then prints out information
about all memory blocks. I'm not sure what "Get In Vars" does, but it
seems to return a pointer into the middle of a DOS data block.
--
Roy J. Mongiovi. Office of Computing Services. User Services.
Georgia Institute of Technology. Atlanta GA 30332. (404) 894-6163
...!{akgua, allegra, amd, hplabs, ihnp4, masscomp, ut-ngp}!gatech!gitpyr!roy
exp(sqrt(-1.0) * 4.0 * atan(1.0)) == -1