VLU 101

Copyright 1987, Esoteric Software Michal Carson
This program is distributed through ZSIG.

 This is a nice documentation file I found for VLU. You will notice that the program was written for use with ZCPR. Don't worry about all the references to ZCPR in these docs. The ADAMVLU.COM program has been patched to work properly on an ADAM with TDOS (or CP/M on a Heath emulation terminal). All
features will work with the exception of the (B)uild a new library feature. VLU usually looks for a drive map in the system memory to tell it various facts about your system, but without ZCPR running, it doesn't know this information.

The other features should more than make up for the lack of library building ability. I prefer NULU or ARK anyway!

--Ron Collins (06/12/90)

VLU is a ZCPR3-specific library utility with crunch, uncrunch, and unsqueeze capabilities. It will allow the user to view, uncompress, or extract library members or to view, uncompress (uncrunch or unsqueeze, VLU will decide), or crunch disk files. VLU will build libraries from disk files, crunching the files as they are added.

The utility will display a list of disk files on the screen along with a cursor and other information. Placing the cursor next to the name of a file with the extension .LBR and pressing 'O' for Open will display the contents of the library and shift the cursor into that directory.

What is a Library?

The Library file format was developed to overcome two persistent limitations of CP/M disk storage capacity: limited directory entries and large blocking.

Although CP/M writes files in units of 128 bytes (sectors), most manufacturers have used larger blocks for storage on disk. On a Kaypro with double-sided disks, for instance, all files are stored in 2K blocks; even a file one sector in length will occupy 2K on the disk. Because the Kaypro disk format allows only 64 directory entries files) on one disk, 64 of these 1-sector files (8K) will fill a 390K disk.

In a library, a one sector file occupies one sector (plus 32 bytes for internal directory information). The library itself occupies only one directory entry on the disk. If 64 one-sector files are placed into a library, the library will occupy 10K.

This is obviously an extreme example but illustrates the usefulness of libraries. Other reasons exist; for nstance, libraries keep related files together. VLU will make files within libraries more accessible.

In this Library

Two executable versions are distributed: VLUxxx-R.COM is for machines using reverse video as highlighting. VLUxxx-D.COM is for machines using dim video as highlighting. VLU.FOR is a short description of the utility; VLU.HLP is full documentation compatible with the ZCPR3 HELP text display utility.

The Help display

Pressing "/" or "?" will evoke a display summarizing the commands available to the user. These commands change according to Wheel status and directory choice (e.g., Delete is not available in the library and is never available to non-wheels). Pressing either of these keys a second time will clear the display.

Invoking VLU

Use VLU as an extension to a ZCPR3 shell, such as ZFiler, invoked through a macro. To install it, one need only open the ZFILER.CMD file with a word processor and enter a line of the form "1 vlu".

Thereafter, positioning ZFiler's cursor beside a library file and pressing "1" (possibly preceded by [esc]) will bring up VLU with the library already open. A better thought is to assign this macro to the "O" key--"O d1$u1:;vlu" in ZFILER.CMD--so that [esc] "O" will open the indicated library.

Some aspects of VLU were designed to make it an extension of tools like ZFiler. Most of these tools use the ZCPR system files to store the name of the current file (the file the cursor was pointing to on exit). VLU checks these filenames and interprets the current file (sys file 2) as a library. On starting up, VLU will try to open a library file of this name in the current directory.

This allows the user to invoke VLU from the "Z" prompt of ZFiler or through a macro, pass no parameters, yet open the current file if it is a library (or shares the same name as a library though it may have a different extension). If a different library is opened before returning to ZFiler, VLU will modify the filename in system file 2 (and thus cause ZFiler to believe it was pointing to this library when it exited).

As a command file, VLU can, of course, be invoked from the system command prompt. If a library name is entered on the command line, that name will take priority over any name currently in system file 2 and the library will be opened if it exists. Even from ZFiler's "Z" prompt, with the pointer on ABC.LBR, entering the command "VLU DEF" will open DEF.LBR and place that name into system file 2.

VLU can be re-entered with the GO command.

Changing libraries

When a library is opened, when VLU is invoked with a library name in the command line, or when a new directory is logged in with a library open, the VLU cursor will point into the library directory. Pressing the [esc] key will shift the cursor back into the disk directory. Opening a different library is as simple as positioning the cursor in front of the name and pressing "O".

Cursor motion

Moving the cursor (pointer) in VLU is effected using the WordStar cursor motion controls. Ctrl-E moves the cursor up one line, ctrl-X moves it down. Ctrl-S moves the cursor left one file, ctrl-D moves it right. Ctrl-F brings a new directory onscreen if there are more files in the directory (as if the display were moving right by a directory), ctrl-A moves back toward the beginning of the file list. Ctrl-F will wrap around from the final directory to the original.

The arrow keys will also function if they are properly defined in the users Environment descriptor. The symbols "+" and "-" (and "=", the usual non-shifted counterpart of "+") have the same effect on the directories as ctrl-F and ctrl-A, respectively.

The [esc] key shifts directories: from the library to the disk, from the disk to library. In most instances the cursor will "remember" where it was when it last pointed into that directory.

Extracting and Uncompressing library members

Positioning the cursor beside the name of a member file within a library and pressing "E" for Extract will cause the file to be copied from the library to the disk with no change in form. If it is crunched or squeezed within the library, it will be crunched or squeezed on the disk.

Pressing "U" for Uncompress will cause a crunched file to be uncrunched onto the disk, a squeezed file to be unsqueezed onto the disk, or an uncompressed file to be extracted sic.

Changing directories

Library members may be extracted to a disk and/or user area other than the one which contains the library. Open the library first, then use the Login command to move to the destination directory and perform the extraction or decompression. The move is accomplished by pressing "L" (cursor position makes no difference with this command) and answering the prompt "Directory ". The user may enter a DU: specification (e.g., A0:, B14:, F:) or the name of a ZCPR3 named directory to be found in the current system (e.g., MODEM:, DUNGEON:). The colon is not necessary in any case and an invalid directory or denied access will relog the current area. No entry at all will also relog the current area to facilitate disk changes.

Tagging files

The "T" command will tag an untagged file and the "Y" command will remove the tag from a tagged file. The tag appears as a hash (#) immediately following the filename. After a group operation (actually, during the group operation) hard tags represented by the hash are replaced by soft tags which appear as an apostrophe ('). Soft tags may be transformed back into hard tags by the retag command: "*". Wildcard tagging is accomplished by pressing "W" and providing a wildcard file specification in response to the prompt. All files in the directory, starting from the beginning, which match the file spec will be tagged.

Group Tag ("GT") is equivalent to a *.* wildcard tag.

It may be convenient at times to untag all files. This can be accomplished by relogging the directory with the Login command. Certain file operations which affect the disk directory (anything that adds or deletes files) will also end by relogging the directory and any remaining tags will be erased. Group operations obviously prevent this relogging until all files have been operated upon.

Group operations

"G" will evoke the Group prompt. From this prompt, several commands are available to wheels. Only the View command is available to non-wheels and it will be executed immediately. If the wheel byte is not zero, the prompt will indicate by the first letter of each command that View, Tag, Uncompress, crunch, and either Extract or Delete and Build are available. Any selection is carried out on all tagged files. The Group manager will check for ctrl-C between each file and abort if it is seen.

Viewing files and library members

Crunched, squeezed, and uncompressed files may be viewed by pressing "V" at the VLU prompt. The screen will clear, the file's name will appear at the top of the screen and the file will be presented. The display will stop with the prompt "[strike any key]" after, in general, 22 lines. The number of lines (the size of a screen page) is taken from the ZCPR3 Environment descriptor.

The number provided there, by convention, is two lines less than the screen height. This should give the viewer two lines of overlap with each page. If this is unsatisfactory, the user's Environment descriptor can be adjusted.

At any time during the viewing, pressing ctrl-S will pause the display. Pressing ctrl-C will abort the operation. Under Group control, ctrl-C will abort the entire operation and no more files will be presented; the user will be returned to the file directory display. Unscreened files will remain tagged. Ctrl-X may be used to skip to the next file under Group execution; it has the same effect as ctrl-C if only one file is being viewed; id est, we abort.

At the "[strike any key]" prompt, pressing the period will bring one more logical line to the screen.

Ctrl-Z will suppress the "[strike any key]" prompt and the file will scroll continuously. The viewer is then left with ctrl-S to stop the display (and any key except ctrl-X and ctrl-C will restart it). Another Ctrl-Z will restore the paging mode and stop the screen immediately. This is handy for long files when the interesting text is near the end.

Certain file extensions are proscripted (e.g., COM, LBR, ARK, SYS, RCP, REL, PRL, etc.) and VLU will give the message "may not type" followed by the file name. Crunched files of proscripted types may have a "stamp" of interest to the user. If a proscripted file has a "Z" in the extension (e.g., CZM, RZL, etc.) VLU will give the filename as it appears and attempt to extract the original filename and any stamp contained in the first record of the file.

Crunching disk files

The crunching faculty of VLU is incidental. Because of the Group operations, it may be quite useful and may become addictive, but crunching files on disk is secondary to the project of crunching files into libraries. Selecting "K" at the command prompt will cause VLU to crunch the file pointed to by its cursor.

VLU will first prompt for a "stamp." By convention, this is a message of up to 40 characters enclosed in square brackets. The message is imbedded in the first record of the crunched file to be displayed when the file is either uncrunched or viewed. Often, the message reports the date of the crunching, the author or origin of the file, or its expanded size.

VLU will allow the entry of up to 38 characters. Two characters are reserved so that VLU can insert the square brackets if the user omits one or both. VLU will remove any trailing spaces from the message; if the user wishes the spaces to appear, the user must enter at least the final closing bracket.

The crunching operation will be aborted if the file is already compressed (either crunched or squeezed) or is of a proscripted filetype. Proscripted filetypes are LBR, ARC, ARK, BAD, and, if the target is a library, FOR and CIM (vide infra).

VLU will allow the user to crunch a member out of a library onto the disk. There seems no harm in such an operation (and as little use).

File size report

The size of a file in kilobytes is reported when the user presses either "F" or carriage return. If the file is a library member, the size will also be reported in records.

Renaming disk files

VLU will not rename a library member. To rename a disk file, position the cursor beside the file and press "R". Enter the new name at the prompt.

Deleting disk files

VLU will not delete a library member. To delete a disk file, position the cursor beside the file and press "D". The user will be prompted to confirm that the file is to be deleted. Under Group execution, if the user selects Delete, the prompt will appear for each file. Currently, there is no provision to avoid this prompt.

Building libraries

In order for VLU to build a library, all files to be included must be located in the same directory. The library may, if necessary, be built in a foreign directory.

As distributed, VLU will crunch all files as they are added to the library (unless the extension is unacceptable as previously stated). See the configuration section for possible attenuation of this practice.

To initiate the construction, tag the files which are to be included and then type "GB" for Group and Build. VLU will prompt for the name and directory of the "new library" and the number of entries to allow. A carriage return at the "entries" prompt will build a library with the minimum directory size, only large enough to accommodate the currently tagged files. The largest library that may be built with VLU is 255 entries.

VLU will then initialize the library directory area. The directory list (onscreen) will be reset to the first screen; the cursor will move to the first tagged file and a message will display that the file is being crunched or added as appropriate. If any files are to be crunched, the "stamp" prompt will appear and the stamp thus entered will be in effect for all files crunched into the library.

Under this operation, as under the Wildcard and other Group operations, the directory list onscreen will shift through all files searching for tags. This will be more noticeable in larger directories (which require more than one display) and during the Building of libraries (because of the pause to close the library).


There are five configuration bytes. The first, at 10Ch, controls the display of files whose system bit is set. Zero value in this location will display such files, any other value will suppress their display. Default as distributed is "not displayed."

The second byte was added in order to accommodate LDR v1.6. This version of LDR allows all ZCPR3 system segments to be packed into a single library, saving disk and directory space. If the byte at 10Dh is of zero value, all system segments will be crunched according to the rules governing other files. If the user wishes to be prompted when a system segment is detected--given the option of crunching or not--the byte at 10Dh should be not zero. Default as distributed is "prompt."

The third byte (10Eh) controls a prompt in the library building routines. If this byte is not zero, the user will always be prompted before a file is crunched. This gives the opportunity to load uncompressed files to the library. The fourth byte (10Fh) is dependent on the third. If the third byte is zero, there will be no prompt and all files will be loaded to the library on direction of the fourth byte. If the fourth byte is zero, all files will be loaded sic; if not zero, files which have passed VLU's other criteria will be crunched. The fourth byte has no effect if the third byte is not zero. Default as distributed is "no prompt, crunch when possible."

The fifth byte (110h) is a bit map of fixed media. The most significant bit represents the A: drive; the least significant, the H: drive. If the bit is set (1), the drive will not be reset on logging to a new directory. If the bit is reset (0) a disk reset (BDOS function 37) will be performed each time the Login command is used. This takes some time; users with Hard Disks and RAM disks are encouraged to configure this byte to match their system. Users with only floppy disk drives should leave the byte in its default as distributed: "no fixed media" (00h).

The value needed in this byte to indicate that the A: drive is not to be reset is 80h. The value for A: and B: is C0h.

Following the five configuration bytes, the user will note the two file extents FOR and CIM. This location contains a list of filetypes which the user does not wish to be crunched in building a library. More filetypes may be patched into this list; the list must be terminated by a null.

Option menu

The Option menu, accessed by typing "M" at the command prompt, will toggle any of the first four configuration bytes. This allows temporary assignment of the options to display/suppress system files, prompt before crunching system segments, and prompt before crunching files into libraries.


The Login command of VLU will use the Z33 parser when it is available, thus behaving exactly as the operating system would in allowing admittance to directory areas. When Z33 is not available, VLU allows immediate entry to any du: or dir: within the MAXDSK and MAXUSR limits of the environment. Dir: forms outside these limits are also accepted; passwords, if present, are enforced.

Commands Delete and Rename and any commands that would create new files are available only while the wheel byte is set.


VLU directly incorporates the work of many "better makers." My thanks to all of them as much and more for the opportunity to read and learn from their code as well as for their library releases.

Among them, the following:

Richard Conn, Howard Goldstein, Jay Sage, Al Dunsmuir et al. for SYSLIB, Z3LIB, Z33LIB04 and VLIB--and ZCPR, itself.

C.B. Falconer and Steven Greenberg for USQREL, UNCREL, CRN, and BUFFERS.

Steven Cohen for M24.

Martin Murray for NULU, the standard for these efforts. And Gary Novosielski for the library format.

Note from the programmer

Please notice that VLU is not a shell. If there are good arguments for making it a shell, please forward them to me. Other functions are planned; next upon the board is output to printer.

If you have requests or ideas, contact me.

VLU, its source code, and its documentation are copyright 1987 by Esoteric Software. VLU is distributed for non-commercial use only; any commercial use or any re-distribution in association with a commercial product or package requires the prior written permission of the author.

I may be reached on Z-nodes 2 and 3--Al Hawley's Ladera and Jay Sage's Newton Centre; both are available via PC-Pursuit. I log into these nodes approximately weekly. If it is important to reach me sooner, my home Z-node is #58, operated by Kent Mason in Oklahoma City (405/943-8638). You should check into this node anyway; there aren't many Kaypros online with 1Meg of memory.

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