C11) CHKDSK reports 639K (or less) total memory on my system; am I
     infected?

If CHKDSK displays 639K for the total memory instead of 640K (655,360
bytes) - so that you are missing only 1K - then it is probably due to
reasons other than a virus since there are very few viruses which take
only 1K from total memory.  Legitimate reasons for a deficiency of 1K
include:

1) A PS/2 computer.  IBM PS/2 computers reserve 1K of conventional
  RAM for an Extended BIOS Data Area, i.e. for additional data storage
  required by its BIOS.
2) A computer with American Megatrends Inc. (AMI) BIOS, which is set
  up (with the built-in CMOS setup program) in such a way that the BIOS
  uses the upper 1K of memory for its internal variables.  (It can be
  instructed to use lower memory instead.)
3) A SCSI controller.
4) The DiskSecure program.
5) Mouse buffers for older Compaqs.

If, on the other hand, you are missing 2K or more from the 640K, 512K,
or whatever the conventional memory normally is for your PC, the
chances are greater that you have a boot-record virus (e.g. Stoned,
Michelangelo), although even in this case there may be legitimate
reasons for the missing memory:

1) Many access control programs for preventing booting from a floppy.
2) H/P Vectra computers.
3) Some special BIOSes which use memory (e.g.) for a built-in calendar
  and/or calculator.

However, these are only rough guides.  In order to be more certain
whether the missing memory is due to a virus, you should:
(1) run several virus detectors;
(2) look for a change in total memory every now and then;
(3) compare the total memory size with that obtained when cold booting
  from a "clean" system diskette.  The latter should show the normal
  amount of total memory for your configuration.

Note: in all cases, CHKDSK should be run without software such as
MS-Windows or DesqView loaded, since GUIs seem to be able to open DOS
boxes only on whole K boundaries (some seem to be even coarser); thus
CHKDSK run from a DOS box may report unrepresentative values.

Note also that some machines have only 512K or 256K instead of 640K of
conventional memory.


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