*** Peter Magnusson wrote in a message to Scott McNay:
 SM> Bypassing the BIOS, in this case, means that the interrupt
 SM> vectors are reinitialized with new values.  Therefore, the
 SM> TSR would never get called.
PM> You mean they communicate directly with e.g the IDE
PM> interface? 
Yes, they replace the BIOS code.
Writing code to access the IDE ports isn't all that hard...
... the hard part is getting the code to work properly. 
The ATA spec is kinda obscure from a programmer's viewpoint, in my opinion.
 SM> This is why DOS boot-sector
 SM> viruses don't normally spread under those environments.
PM> "DOS boot-sector viruses" ;-)
Ok, 16-bit mode boot-sector viruses.  ;)
--Scott.
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