> Hi All!
 >        What's the difference between a .COM file and a .SYS file (such
 > as a
 > driver loaded as DEVICE= ).  Does it use ORG 0h as opposed to ORG 100h,
 > for
 > example?
Device drivers do have ORG 0, yes. They also, however, have a specfic data 
structure at the beginning which is for the device driver loader to find out 
what type of device driver it is, where the initialisation code lives, and 
much more. I seem to recall "Advanced MS-DOS" by ray duncan had some really 
good device driver code, in assembler (or was it TSR code?) - it's an old 
book so try a library. PC magazine published some device drivers in the 
late-80's also, in asembler, with source, I think. Again, try the library.
It's also a bit trickier to compile device driver code..
Ralf Brown's interrupt list doccuments the device driver structures.
    Craig
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