PHYS169@csc.canterbury.ac.nz (Mark Aitchison, U of Canty; Physics) (03/28/91)
[Ed. WARNING! DANGER! This topic has come up before in the past and has lead to much speculation and drawn out conversations. At one point, a submitter consulted the IBM PC Technical Reference manual and determined that the write protection on a standard IBM PC 5.25" disk drive to be indeed located in hardware. While I welcome open discussion on this issue, I will only post follow-ups which cite specific technical references. That is, no "I heard that you can..." type of stories! I thank everyone in advance for helping me out on this.] Someone asked me recently whether it is possible that some disk drives can write on a write-protected floppy. I know that modern drives (that are working properly) block this at the controller level, so even if a virus wrote directly to the diskette controller ports, bypassing BIOS as well as DOS, it wouldn't be able to write. But can anyone answer for sure whether there any, perhaps older, drives where it is possible? I know that some 8" diskette drives used the opposite standard for write-protection (a tab *enables* writing). Anyone know of 5.25" drives that are non-standard or bypassable?? Otherwise, I'm guessing his disk was already infected, or he used it on a drive where the write protect or cable was faulty. Morale of story: Check even your write-protected diskettes! Thanks, Mark Aitchison, Physics, University of Canterbury, New Zealand.