Simtel MSDOS 1992 June

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READ THIS BEFORE PRINTING!!!! This document has been formatted in a special way. Virtually all dot matrix printers have a condensed mode which prints 132 characters across a standard 8 1/2 inch page. When this file is printed out in condensed mode, the resulting printed pages can be cut down to 5 1/2 X 8 1/2 inches. The cut pages will fit nicely in the back of your DOS manual for storage. Typically, you can turn on this mode by sending a special control sequence to the printer from BASIC. For example, you can turn on the condensed mode of the IBM/Epson printer with the BASIC statement: LPRINT chr$(15). If your printer has such a condensed mode, turn it on now, before printing the rest of this document. (tm) VPRINT Virtual Printer Utility for the IBM Personal Computer User's Manual (c) 1986, 1987 by David Whitman Version 3.01 David Whitman P.O. Box 1157 North Wales, PA 19454 (215) 234-4084 (evenings only) Table of Contents What is VPRINT?.............................................1 System Requirements.........................................2 Starting VPRINT.............................................3 Advanced Usage..............................................4 Emulation Options...........................................5 Filter Options..............................................6 Enable Options..............................................7 Miscellaneous Options.......................................9 Limitations................................................10 Miscellaneous and A Word From Our Sponsor..................12 Registration Form..........................................17 1 >> What is VPRINT? << VPRINT implements a "virtual printer" by capturing output normally sent to your printer and redirecting it to a file of your chosing. There are many reasons you might want to capture printer output: * Producing formatted files from software packages that don't support "printing to disk". * Setting up word processors and other programs to work with your printer. By capturing to disk, you can see exactly what's being sent, and pinpoint problems immediately. * Capturing output generated on one computer, to be printed on a different system. * Taking disk "snapshots" of your video screen. When VPRINT is running, the PrtSc key copies the screen to your disk file. * Delaying printer output for later printing. VPRINT responds much faster than a "real" printer, but takes up much less memory than most print spooling software. If you can't afford the memory for a print spooler, you can VPRINT quickly, then print the file later during a time when your computer is idle. 2 >> System Requirements << To run VPRINT, you need: IBM PC 64K of memory, minimum 1 disk drive, minimum DOS 2.0 or later VPRINT is designed to run on IBM PCs, but should run on all systems that are compatible with the IBM BIOS. The following systems are known to run VPRINT successfully. If you are using VPRINT on a computer not on this list, please write, and the list will be updated so that others can share this information. IBM PC IBM XT IBM 3270 PC IBM 3270 PC/G 3 >> Starting VPRINT << To capture printer output, you must "install" VPRINT. Installation temporarily grafts a portion of VPRINT onto your computer's input/output system. Once installed, VPRINT remains a part of the I/O system until you either shut your computer off, or reset the system by pressing Ctrl-Alt-Del. To install VPRINT, type: VPRINT filename.ext /i Use whatever filename you'd like printer output to be sent to. The filename can optionally have a drive and/or pathname. If you don't use a filename, VPRINT will create a file named VIRTUAL.PRN for you in the root directory of the default drive. The "/i" tells VPRINT that you want to install the program, and if a filename is used, the "/i" must come AFTER the filename. After you type the above command, VPRINT will respond: VPRINT - virtual printer (version 3.01) User-supported software by D. Whitman For help/info, type VPRINT ? Resident section has been installed. As programs attempt to send output to your printer, VPRINT intercepts the output, and stores it in an internal buffer. Every time this buffer fills up, VPRINT dumps the buffer to the disk file you specified during installation. After you have finished your printing, the buffer may still contain some of your output, not yet transferred to disk. Before using the output file, you should ask VPRINT to "flush" the buffer, using the command: VPRINT /f 4 >> Advanced Usage << The procedure given in the previous section will allow you to capture printer output from most software packages, but does not make use of all of VPRINT's capabilities. This section will discuss these further options. The VPRINT command has the following syntax: VPRINT [?] [d:][path][filename[.ext]]] /options If you type VPRINT ?, a one page help screen will be printed. You can specify a fully qualified file name, including drive and path. After installation, you can change the active printer file by running VPRINT with a different filename. This modifies the resident code without loading a new copy or using more memory. VPRINT's options all start with a slash character "/" followed by a single letter or number. If a filename is used, the options must come AFTER the filename. Multiple options can be used. The following options are available: /i install (required to load resident code) /f flush - empty any buffered output to disk /s report status /1 emulate LPT1: /2 emulate LPT2: /3 emulate both printers (default) /n neutral - don't filter output (default) /l drop LFs, expand CR to CR LF /c drop CRs, expand LF to CR LF /d disable - flush buffer, use physical printer /e enable - use virtual printer again, after /d /h harmless output - use ultra-safe output (default) /r risky output - allow some risk in output Again, like the filename, you can install VPRINT using one set of options, then change by running VPRINT again with different options. The new options will modify the resident code without using more memory. The following sections will discuss these options in more detail. 5 >> Emulation Options << You can control which printer port(s) VPRINT emulates. By default, VPRINT redirects printer output intended for both LPT1: and LPT2:. You can restrict this to only one printer using options /1 and /2. For example, if you only want to capture output from LPT1:, you would install VPRINT like this: VPRINT /i /1 Alternatively, if VPRINT is already installed, you can restrict capture to LPT2: with this command: VPRINT /2 The /3 option returns you to the default state, where output to both printer ports is captured. 6 >> Filter Options << By default, VPRINT stores to disk exactly what is being sent to your printer. However, under certain circumstances, it is desirable to "filter" the output slightly. Standard DOS files end each line with a carriage return character (CR), followed by a line feed character (LF). Many programs, including most word processors, will require files to be in this format. Unfortunately, when sending output to a printer, not all programs terminate lines with a CR LF pair. For example, Volkswriter sends only line feeds at the end of blank lines. This works fine when sent to a printer, but if captured to a file, the resulting file will look very strange when re-edited. (Multiple blank lines disappear, and are replaced with a single line full of boxes with holes in them -the screen representation of the line feed character.) At least on older PC's, the PrtSc function acts even stranger. PrtSc terminates each line exactly backwards, with a LF followed by a CR. This combination will confuse most text editors, causing very strange behavior. VPRINT has two "filtering" modes which tend to force printed output into standard DOS format. These modes ignore either CRs or LFs, while replacing the other character with a CR LF pair. Option /C ignores carriage returns, and expands LF to CR LF. Similarly, /L ignores printed line feeds, but adds one after each CR. If your captured output looks strange, try turning on the different filtering modes and see if your output looks more normal. You can turn off filtering with the /N option. After /N is in effect, output will again be captured verbatim. 7 >> Enable Options << Once VPRINT is installed, it remains a part of your computer's input/output system until you either turn off your computer or re-boot. However, VPRINT can be temporarily disabled to allow output to go to your printer as usual. Option /D disables VPRINT. When /D is in effect, VPRINT remains resident, but passes output unmodified to your printer. Option /D also flushes VPRINT's internal buffer, so that all your output is available on disk. Option /E enables VPRINT, presumably after it's been disabled with option /D. When option /E is in effect, printer output is once again redirected to your disk file. 8 >>Output Mode<< For technical reasons, it can be dangerous for a memory resident program like VPRINT to perform disk access. If disk output is performed at an inopportune moment, your computer could lock up and require rebooting. To help avoid this situation, VPRINT supports two modes of disk output. Option /H specifies harmless output, and is the default mode. When /H is in effect, VPRINT will only attempt to write to disk under circumstances it KNOWS will be safe. However, this can present a problem if VPRINT's internal buffer fills up before a known safe opportunity occurs. VPRINT addresses this situation by accepting as much output as possible, then simply ignoring additional characters until an opportunity for output occurs. Whenever VPRINT's buffer is getting too full, a status signal is returned after each print request indicating that your printer is "turned off". If your software monitors printer status during output, it should stop and ask you to correct the situation. Often, VPRINT will be able to dump its buffer to disk during the time your software is asking you to turn the printer back on. You should be able to restart printing immediately, with no other action on your part. If the restart is unsucessful, abort printing, and try changing VPRINT's output mode to /R. Option /R specifies risky output. When /R is in effect, VPRINT will write output to disk whenever its internal buffer fills up. You should use risky mode with programs that don't intelligently monitor printer status during printing, and might lock up or continue to output after VPRINT's buffer was full. While it is safer and preferable to use "harmless mode", most programs will be compatable with "risky mode". (In fact, earlier versions of VPRINT used only this mode.) Incompatibility will be obvious; your computer will lock up after a few pages of output, and you'll need to reboot. NOTE: Since it *is* slightly risky, it's probably a good idea to back up any data on your system prior to activating option /R. 9 >> Miscellaneous Options << A short help summary will be printed if you type VPRINT ?, or just VPRINT with no other options. The /I option installs VPRINT. This option loads VPRINT's resident code, and grafts it onto the I/O system of your computer. Once VPRINT is loaded, there is no need to specify /I on subsequent commands. If you use /I when the resident code is already loaded, VPRINT will detect the resident code and will print an error message without re-loading. Option /F flushes VPRINT's internal buffer to disk. To avoid constantly running your disk drive during printing, VPRINT collects about 2000 characters, then writes them to disk all at once. Unless you output an exact multiple of 2048 characters, when printing is finished, part of your output is still in VPRINT's internal buffer. Option /F forces the last part of your output to disk. Incidentally, VPRINT's internal buffer is automatically flushed before shifting to a new file, and also before disabling, if you turn on option /D. Option /S prints a status report, indicating which options are in effect, and where your printed output is being sent. This is the same report which is printed after using any of the other options, but /S allows you to check status without changing anything. 10 >> Limitations << VPRINT writes to your disk drive using functions provided by DOS. Technically, it is "illegal" for the input/output system to get services from DOS (the organization is such that DOS is supposed to get services from the input/output system, not the other way around) but under almost all circumstances, VPRINT gets away with this irregularity, particularly when harmless mode is active. Although it would have been possible to design VPRINT to go around DOS and take direct control of one of your disk drives, this would run the risk of destroying data on the disk if something went wrong. By asking DOS for services, disk data is best protected, but at the risk of locking up your system under certain rare circumstances. The technical problem is caused by a phenomenon called re-entrance. If VPRINT calls DOS for services when DOS is already busy, things can get messed up, and your system can crash. Particularly bad is the situation where the same section of DOS that VPRINT calls for disk output is calling VPRINT for printer output. Situations where DOS treats your printer like a disk file tend to give VPRINT problems. For example, when VPRINT is installed in risky mode, the following DOS command will often lock up your system: COPY filename1 PRN DOS treats device PRN like a disk file, and when VPRINT calls DOS for services, the appropriate routines are already in use. A lock up can result. Note that there would be no point in issuing this command with VPRINT resident, since you could accomplish the same task with: COPY filename1 VIRTUAL.PRN 11 Similar lock-ups can occur if you perform i/o redirection to one of DOS's reserved printer devices. For example, in risky mode: DIR >LPT1: will sometimes lock up the system. Again, with VPRINT resident, you can accomplish the same thing (safely) with the command: DIR >VIRTUAL.PRN Another source of lock-ups would occur if you specified one of DOS's printer devices as the file for VPRINT to use. For this reason, VPRINT will reject filenames PRN, LPT1: or LPT2:. Again, there is no reason to want to VPRINT to one of the printer devices. To send output to a printer, just disable VPRINT with option /D. 12 >> Miscellaneous and a Word From Our Sponsor...<< A. Programming Notes 1. VPRINT is written in assembly language for maximum speed and minimum size. The source code is available to registered users by sending a formatted disk and a stamped return mailer. The source code is in the syntax of the CHASM assembler, which is another product of Whitman Software. A one page advertisement for CHASM is given near the end of this document. If you make any improvements in VPRINT, I'd like to hear about them for possible inclusion in future releases. Please note that although you can modify VPRINT for your own use, under NO CIRCUMSTANCES may you distribute modified or translated versions, either in the public domain or for profit. 2. VPRINT monitors BIOS interrupts 17H (PRINTER_IO), and 28H (DOS_IDLE). No other interrupts are affected. Virtually all software interfaces to the parallel ports via interrupt 17H. Obviously programs which bypass the BIOS for printer output will be unaffected by VPRINT. DOS_IDLE is an undocumented interrupt which is executed by DOS during keyboard input, and possibly other times. Disk i/o is safe during int 28H, and intercepting this vector is one of the methods VPRINT uses to perform "harmless mode" output. The DOS PRINT command functions by intercepting int 28H. 3. To change options in the resident code, VPRINT examines the vector for interrupt 17H, then searches at the specified location for a "recognition string". If this recognition string is not matched, changes are aborted. If you load another memory resident program after VPRINT that intercepts interrupt 17H, you will not be able to change options or files used by the resident part of VPRINT. 13 4. DOS is not re-entrant, and it is supposed to be illegal for interrupt handlers to call DOS. VPRINT seems to get away with it though, and the function seems useful enough justify the risk of a system crash. I strongly urge that you back up all data before turning on risky mode. B. Red Tape and Legal Nonsense: 1. Disclaimer: VPRINT is distributed as is, with no guarantee that it will work correctly in all situations. In no event will the Author be liable for any damages, including lost profits, lost savings or other incidental or consequential damages arising out of the use of or inability to use this program, even if the Author has been advised of the possibility of such damages, or for any claim by any other party. Despite the somewhat imposing statement above, it *is* my intention to fix any bugs which are brought to my attention. Note that since VPRINT breaks one of DOS's rules, there may be circumstances which have no possible correction. 2. Copyright Information The entire VPRINT distribution package, consisting of the program, documentation file, and source code file are copyright (c) 1986 and 1987 by David Whitman. The author reserves the exclusive right to distribute this package, or any part thereof, for profit. The name VPRINT (tm) applied to a microcomputer printer redirection utility is a trade mark of David Whitman. The VPRINT package (with the exception of the source code file VPRINT.ASM) may be freely copied by individuals for evaluation purposes. It is expected that those who find the package useful will make a contribution directly to the author of the program. 14 VPRINT's source code is made available to registered users for educational purposes and to allow them to customize for their own personal use. The source code file is available only to those who make the suggested payment for use of VPRINT. Under NO CIRCUMSTANCES may modified versions or translations into other computer languages be distributed, either for profit or in the public domain. User's groups, clubs, libraries and clearing houses are authorized to distribute VPRINT under the following conditions: 1. No charge is made for the software or documentation. A nominal distribution fee may be charged, provided that is no more that $8 total. 2. Recipients are to be informed of the user-supported software concept, and encouraged to support it with their donations. 3. The program and documentation are distributed together and are not modified in ANY way. 4. The source code file VPRINT.ASM or disassemblies of VPRINT.COM may not be distributed. C. An Offer You Can't Refuse. VPRINT is user-supported software, distributed under a system identical to the FREEWARE (tm) marketing scheme developed by the late Andrew Flugelman, whose efforts are gratefully acknowledged. Anyone may obtain a free copy of VPRINT by sending a blank, formatted diskette to the author. An addressed, postage-paid return mailer must accompany the disk (no exceptions, please). A copy of the program, with documentation, will be sent by return mail. The program will carry a notice suggesting a payment to the program's author. Making the payment is totally voluntary on the part of the user. Regardless of whether a payment is made, the user is encouraged to share the program with others. Payment for use is discretionary on the part of each subsequent user. 15 The underlying philosophy here is based on the following principles: First, that the value and utility of software is best assessed by the user on his/her own system. Only after using a program can one really determine whether it serves personal applications, needs, and tastes. Second, that the creation of independent personal computer software can and should be supported by those who benefit from its use. Remember the Tanstaafl principal: There Ain't No Such Thing As A Free Lunch. Support to authors encourages the continued creation of novel, low cost software. Finally, that copying and networking of programs should be encouraged, rather than restricted. The ease with which software can be distributed outside traditional commercial channels reflects the strength, rather than the weakness, of electronic information. If you like this software, please help support it. Your support take three forms: 1. Become a registered user. The suggested payment for registration is $15. 2. Suggestions, comments and bug reports. Your comments will be taken seriously. VPRINT will evolve over time, based on the feedback of users. 3. Spread the word. Make copies for friends, or send the program to your favorite BBS. Astronomical advertising costs are one big reason that commercial software is so overpriced. To continue offering VPRINT this way, I need your help in letting other people know about VPRINT. 16 Those who make the suggested $15 payment to become registered users receive the following benefits: 1. Access to VPRINT's heavily commented source code. 2. User support, by phone or mail. SUPPORT IS ONLY AVAILABLE TO REGISTERED USERS. 3. Notices of significant upgrades. 4. A warm, fuzzy feeling of having done the right thing. The converse is also true. If you continue to use VPRINT without making the suggested payment, your self-image will gradually deteriorate until you wake up one day in the gutter on Skid Row, grubbing for cigarette butts and discarded floppy disks. Honest. This documentation file was written using Volkswriter 3, then printed and captured by VPRINT to eliminate Volkswriter's special effects markers and get proper pagination. Option /C was in effect to force line feeds into CR/LF pairs. - Dave Whitman Whitman Software P.O. Box 1157 North Wales, PA 19454 (215) 234-4084 17 >> Registration Form (version 3.01)<< Please send me a copy of the current version of VPRINT, and add me to the list of registered VPRINT users, to be eligible for phone support and upgrade notices. I enclose a check for $15. Note: as of version 2, VPRINT requires DOS 2 or later to run. Computer Model: ______________________________ Diskette Format: ____ single _____ double sided Where did you hear about VPRINT? _______________________ ========================================================= Name: ______________________________________ Address: ______________________________________ City, State, Zip: ______________________________________ ========================================================== Send registration form and check to: Whitman Software P.O. Box 1157 North Wales, PA 19454 18 >> Also Available << CHASM is a full featured assembler for the IBM PC. Substantially simpler than the IBM macro assembler, CHASM is particularly suited for those learning assembly language. Using CHASM you can: * Learn 8088 / 8086 / 8087 assembly language. * Explore the inner workings of the IBM PC. * Write lighting-fast stand alone programs. * Produce machine language subroutines for BASIC programs. * Write external procedures or inline code for Turbo Pascal. Although easy enough for beginners, CHASM is powerful enough for production coding. VPRINT was produced using CHASM. CHASM features macros, conditional assembly, structured variables, operand expressions and much more. A free evaluation version can be obtained by sending a formatted disk and stamped return mailer to: Whitman Software P.O. Box 1157 North Wales, PA 19454 A payment of $40 is requested from those who find the program useful. Those who make this payment are upgraded to a version which runs twice as fast.