COMPARE is a binary file comparison utility program. It does
a byte by byte comparison of two files and reports any differ
ences.
Useage
------
COMPARE [d:]filename1 [d:][filename2]
Where:
d: is an optional disk drive identifier
filename1 is the first file name
filename2 is an optional second file name
Examples
--------
COMPARE ZAP.COM ZOT.COM
This will compare ZAP.COM with ZOT.COM on the currently
logged drive.
COMPARE ZAP.COM B:
This will compare ZAP.COM on the currently logged drive
with ZAP.COM on drive B:.
COMPARE B:ZAP.COM ZOT.COM
This will compare ZAP.COM for drive B: with ZOT.COM on
the currently logged drive.
COMPARE B:ZAP.COM B:ZOT.COM
This will compare ZAP.COM with ZOT.COM both on the B:
drive.
Error Messages
--------------
The program will give an error message if it cannot
successfully open either of the specified files. It will give an
error message if the length of the files does not match. It will
report any bytes which do not match in the files.
++ FILES UNEQUAL IN SECTOR 1 AT BYTE 00
Note that the sector number is equal to the "DUMP COUNT"
displayed by DDH while dumping a file. This makes it easy to find
the sector and byte for examination with DDH.
Internal Prompts
----------------
The prompt:
Do you want file 1 printed as it is compared?....Y/N (CR = N)
This is only appropriate if you are comparing text files.
Replying Y for a COM file will generally give unpredictable
display results and may lock out the terminal.
File Comparison Tutorial
------------------------
This program does a BINARY file comparison and is really
fairly dumb in the way it goes about it. It is mostly useful for
locating small differences in programs such as comparing a
reassembly of a disassembled program to the original COM file or
locating serial numbers, messages etc.
If there are large differences between programs it is highly
likely that once one difference has been located, all following
bytes will be different. If you get more than one screenful of
consecutive mismatches it is probably worthwhile hitting control
C to abort the program.
The program reads one sector from each disk alternatively so
tends to be rather "noisy".
COM files do not contain displayable data as such and so if
a mismatch is reported and you need to see what is actually in
that location in both files, the best way is to use the disk
dumper program DDH to dump out the files....the sector numbers
match the dump count as outlined above.
