Michael J. Mefford 1988 No. 11
Purpose: Displays the differences between two text or two
binary files. Files need not be the same length, and paragraph reformatting changes introduced by word wrap are ignored.
Format: COMPARE filespec filespec[/B][/W]
Remarks: COMPARE's default assumption is that the filenames designated in
filespec are to be compared as ASCII text files. Formatting commands
embedded by word processing programs are reproduced on screen but are not
acted upon. Files in which the "high bit" is set (such as those produced by
WordStar's document mode) can be made displayable in ASCII by entering the
optional /W on the command line.
Files are displayed in two on-screen windows. Differences are shown
in inverse video, and are preceeded by several lines of matching text to
provide a context. When the windows are filled, pressing any key continues to
search for differences; pressing Esc returns the user to DOS. All character
modes, but no graphics modes, are supported.
Files with .COM or .EXE extensions are automatically displayed in
COMPARE's binary mode, which is similar to that produced by DEBUG.COM. Unlike
DEBUG, however, COMPARE uses the IBM/ASCII symbol set rather than periods to
show non-alphanumeric characters, and its segment offset begins at zero rather
than at 100h. Any file can be compared in binary mode by adding the optional
/B switch on the command line.
Note: When COMPARE finds a difference between files it searches ahead up to
400 bytes (the reach value) for a string of 10 (excluding spaces) successive
matching characters (the sequence value). DEBUG.COM can be used to change the
reach and search values on a copy of COMPARE.COM thus:
E 6ED cd ab
E 6F5 cd ab
E 6F9 gh ef
where abcd is the reach value, in hex (default 0190h) and efgh is the
sequence value (default 000Ah).