In a majority of cases, the system doesn't crash when a CD-ROM is in the
drive as described above. However, some non-startup CD-ROM discs have been mastered with data in the boot blocks. When this happens, the computer starts to boot up from the CD-ROM disk but is unable to find a valid system folder and will, then freeze or crash. If a CD is mastered with the first two blocks left blank, the system won't attempt to use the disc as a boot device.
The problem is that the default block size for a CD-ROM drive is 2048 bytes, whereas the default block size for a hard drive is 512 bytes. This
difference can cause the system to read unanticipated areas which may lead
to the problem described above.
Article Change History
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23 May 1996 - Simplified and clarified article.
03 Mar 1996 - Revised and retitled for technical clarity.