DL -- Double Lister, version 1.03

by

Stephen S. Bates

Requires IBM PC/XT/AT/PS2 or compatible, PC-DOS or MS-DOS >= 2.11.

This command displays two files simultaneously on the screen:

DL {d:}{\path\}file1{.ext} {d:}{\path\}{file2}{.ext}

You must give at least one filename. If you omit the second file, the
first file will appear in both windows. Full pathnames are accepted.
You may abbreviate the second file:

1. use '*' in place of filename or ext (or both), OR
2. give d: or \path\ (or both) and omit the filename.ext altogether.

In either case, the missing parts will be supplied from the first file.
(Note: fullblown wildcards are not supported.)

The files will be displayed initially as text in two horizontal
windows, with the first file in the upper window designated as
"active". The active file's name (and path, if there's room) is
displayed in reverse video; its window is framed in double lines.

GETTING OUT

* Strike Q to leave the program. Strike Esc to leave the program and
restore the screen to its original contents.

CHOOSING AN ACTIVE FILE

* Strike + to make the second file active; - to make the first file
active.

* Strike L to enter or leave Lockstep mode. In Lockstep mode, both
files are active; i.e., scroll simultaneously. Lockstep is very useful
for comparing files that are almost alike. NOTE: on some keyboards,
with some versions of BIOS, you may use the Scroll Lock instead of L.

SCROLLING

* To scroll the active file up or down, use PgUp, PgDn, Up Arrow or
Down Arrow. Strike Home to go the top of the file, End to go to the
bottom (but see Limitations, below).

* If you have long lines, you can scroll right or left 20 columns at a
time using Left Arrow and Right Arrow, or one column at a time using
Ctrl Left Arrow and Ctrl Right Arrow. Ctrl Home will return to the left
margin. The column number will be displayed near the file name.

USING OTHER DISPLAY MODES

These keys affect the entire display:

* Strike V to change to a vertical (side-by-side, columnar) display;
strike H to change back to horizontal. Strike V repeatedly when the
display is already vertical to make the left window wider, narrower, or
the same as the right. Strike H repeatedly when the display is already
horizontal to make the upper window taller, shorter, or the same as the
lower.

* Strike 4 to enter or leave 43-line mode on EGA or VGA displays.
Results are unpredictable on mono or CGA displays.

These keys affect only the active window(s):

* Strike T repeatedly to change the tab stop spacing to 1, 2, ... 8
characters. By default, tab stop spacing is 8 characters.

* Strike B to reverse the background color following each line, so that
ends of lines are visible. B also causes tabs to be expanded in shaded
spaces so they can be distinguished from normal spaces. Strike B again
to return to normal display.

* Strike 7 to enter or leave 7-bit display mode. In this mode, the
high-order bit of each character is set zero, and control characters
other than new-line are omitted from the display. 7-bit mode may be set
any time, but is suspended while hexadecimal mode is in effect. This
mode is useful for viewing files created by some word processors.

* Strike X to enter or leave hexadecimal display mode. By default, if
the display is horizontal, sixteen bytes will be shown on each line; if
vertical, eight. The hexadecimal address within the file of the first
byte shown is displayed next to the file name. Hexadecimal offsets from
that starting address are displayed to the left of each line.

Four additional keys (shown in parentheses after "heX" on the help
line) are available only in hexadecimal mode; these assist in aligning
records or arrays within the file for convenient display:

* Strike Tab or Shift-Tab to increment or decrement the file address of
the first byte displayed in hexadecimal mode. Use Up/Down Arrows or
PgUp/Dn to get close to the desired address, then Tab or Shift-Tab to
adjust.

* Strike Ins or Del to increment or decrement the number of bytes per
line, starting from the default eight or sixteen. Striking V, H, or
Home will reinstate the defaults. The offsets to the left of the
line will be changed to reflect the new number.

Note that use of Ins may create display lines longer than the window
width. As in text mode, you may use Right Arrow or Ctrl Right Arrow to
scroll the window to the right. The actions of these keys are modified
slightly in hexadecimal mode for a more readable display.

End of file is not detected in hexadecimal mode; you are not prevented
from scrolling (harmlessly) off the end of the file buffer.

SEARCHING

* Strike F to find the next occurrence of a string within a line. You
will be prompted for a string. Searching is case-sensitive, so enter
the exact desired string. Only ASCII printable characters are permitted
in the search string. The search begins with the second line currently
displayed. To search again for the same string, strike F again and
press Enter when prompted for the string. In Lockstep mode, both files
will be scrolled until the string is found in either file. If the
string is found, the line containing it will be displayed at the top of
its window. If the line is long, or if the display is scrolled left or
right, the found string may not appear onscreen. If it does appear, it
will be brightened. F has no effect in hexadecimal display mode.

* Strike D to locate the next difference between the files. Comparison
begins with the second line of each window, and proceeds until a
difference is found or the end of either file is reached. The first
lines to differ are displayed at the top of the windows. You may then
strike D again immediately, or scroll one file to realign the files
before striking D again. D has no effect in hexadecimal display mode.

LIMITATIONS

DL uses direct video memory display and works only with IBM mono, CGA,
EGA, VGA or HGC or exact compatible display adapters, in an 80-column
text mode only. Appearance may suffer on CGA-composite monitors.

The combined size of both files is limited to available main memory. If
the files are larger, only part of them will be displayed, up to a
maximum of about 128k each. In that case, the End key travels only to
the end of the buffer, not to the true end of file, and the message
"Out of Space" is displayed. The first file has priority on available
memory, so if you have a big and a little file, enter the little one
first.

Lines longer than 2048 characters will be wrapped without warning.

In hexadecimal mode, Ins can increment the number of bytes per line to
a maximum of 511 bytes.

=============

Written by Stephen S. Bates in Microsoft C v5.1 in May 1989. This is
shareware. Permission to copy this program is hereby granted with the
following conditions: you must distribute DL.EXE and DL.DOC (this file)
together and unmodified; you must not charge more than a nominal
distribution fee (maximum $6.00) for a diskette containing the files;
you may not distribute DL with or as part of other commercially sold
software without written permission of the author. In short, you are
not permitted to sell this program for profit in any way, shape or
form.

If you like this program and use it regularly, the author would
appreciate a contribution of $15.00, sent to the address below. As with
all shareware, these contributions are the incentives for authors to
continue distributing quality software in this manner. Only
contributors' questions or suggestions of features for future revisions
will be considered; others will not. Whether or not you contribute, the
author would appreciate being informed of any actual bugs:

Stephen S. Bates
3510 Gramercy
Houston, TX 77025
(713) 665-5817

Thank you.

Revision history:

1.01 11/87 fixed minor bugs; added D feature; made reading of files
quicker.

1.02 12/87 added unequal window sizes feature for H,V; added
heX,Find,End,^Left ^Right ^Home, 7-bit; allowed abbreviated
second filename; made reading of files still quicker;
changed to Microsoft C 5.0 .

1.03 05/89 fixed getting of file names, display of long path names;
fixed problems that slowed display; added "Out of Space"
message, color support, EGA/VGA 43-line mode, background
shading; expanded maximum line size to 2048; added tab-
expansion, hex display start/width adjustments.