Quarterdeck Manifest: Divide Overflow bug

If you use Quarterdeck Manifest, the system diagnostic utility that came with the Quarterdeck Expanded Memory Manager, if you are running the utility either in emulation or on a real PC, there is a bug where in the Disk Adapters section of the Adapters category, if it tries to detect a hard disk (or other media larger than 4,294,967,295 bytes (4 GB - 1 byte), Quarterdeck Manifest will crash with a "Divide Overflow" error and exit.

This is because the Quarterdeck Manifest utility uses 32-bit unsigned values to calculate the size of a whole hard disk .

I have provided a couple of screenshots for evidence.

  1. Here is the first screenshot taken from Virtual PC, largest reported is 522 cylinders, 255 heads and 63 sectors per track:

  2. And here is the second screenshot taken from the AMI486 on 86Box:

The developers at Quarterdeck Office Systems never managed to address the bug even in their latest release of their memory managing utility, QEMM 97. Hard disk and other media larger than 4 GB in size were NOT available at the time when Quarterdeck's products came out and that they were acquired by Symamtec sometime in 1998.

I don't think that there is a way to disassemble the code for the MFT.EXE utility to see why it won't report hard disks larger than 4 GB at all.

The moral of the story: If you want to use Quarterdeck Manifest, don't use a hard disk larger than 4 GB period or remove Quarterdeck Manifest completely. :)

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