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DataPath 1.2 by Bruce Dubbs GDC Software 122 Valencia Dr. Universal City, TX 78148 DataPath Topics Purpose.....................................2 System Requirements.........................2 How to use DataPath.........................2 Examples....................................3 Features....................................5 Technical Details...........................6 Limitations.................................7 References..................................7 Disclaimer..................................8 Modification History........................9 Suggestions for use........................10 Page 2 DataPath - GDC Software Purpose DataPath is used to specify directories, other than the current one, to be searched by executing programs, in the event that a file that needs to be read cannot be found in the current directory. System Requirements DataPath requires 2162 bytes of disk space ( 5 512-byte sectors). It becomes memory resident the first time it is run and increases the size of the operating system by 1440 bytes. It will run on any com- puter using the MS-DOS or PC-DOS operating systems version 2.0 or higher. How to use DataPath Entry Form DATAPATH [d:][pathname [;[d:]pathname]...][/x] where 'd' is the letter of the designated disk drive; and pathname' is a sequence of characters of the form: [\][directory][\directory...][\] Optionally you may use the MS-DOS shorthand notation shown below in lieu of 'directory': . MS-DOS uses this shorthand symbol to indicate the name of the current working directory. MS-DOS automati- cally creates this entry when a directory is made. .. MS-DOS uses this shorthand symbol to indicate the name of the current directory's parent directory. MS-DOS automatically creates this entry when a directory is made. Note: The two shorthand symbols do not exist in the root directory. /x is one or more of the following switches: /V, verbose mode, or /Q, quiet mode, or /R, allow file opens for read only, or /W, allow file opens for read or write, or /H, display help information. Page 3 DataPath - GDC Software Example 1 If you are in directory \DATA and you want to use your copy of dBASE II which is in subdirectory \DBASE to work on data in your current directory, use the following sequence of commands: DATAPATH \DBASE<return> PATH \DBASE<return> DBASE<return> Example 2 If you want to see the current DataPath, type: DATAPATH<return> The current DataPath will be displayed. Example 3 If you want to disable DataPath type: DATAPATH <return> One or more blanks should be typed after the command before the return. Example 4 If you have all your DOS programs on a subdirectory named \DOS, Lotus 123 files in a subdirectory named \LOTUS, dBase files in a subdirectory named \DBASE, and an editor in a sub- directory named \EDITOR, and you want to access any of the programs from any subdirectory, use the following sequence: PATH \DOS;\LOTUS;\DBASE;\EDITOR DATAPATH \DOS;\LOTUS;\DBASE;\EDITOR Note: This configuration will add a noticeable time delay to most applications that read files and to COMMAND.COM find- ing most programs. Using batch files to set PATH and DataPath is a much cleaner and quicker method. Page 4 DataPath - GDC Software Example 5 If your programs are on disk A and your data is on disk B, use this sequence: PATH A: DATAPATH A: or alternatively to search both disks from either loca- tion: PATH A:;B: DATAPATH A:;B: This example assumes that all files on drives A and B are in the root directory. Subdirectories are not of great use on 360K floppy disks, however, DataPath will work properly on floppy diskettes. Example 6 You want to enable spelling dictionary files on subdirec- tory \WORD to be accessed when opened for writing and you want to suppress the DataPath messages: DATAPATH C:\WORD/W/Q Messages will remain suppressed until verbose mode is reset. Example 7 You want to reset DataPath to search the \BIN subdirec- tory, disable opens for read, and reset verbose mode. DATAPATH C:\BIN/V/R Example 8 You want to display quick help information about the data path and its switches. DATAPATH /h The data path will not be updated if the /h switch is pre- sent. Page 5 DataPath - GDC Software Features DataPath supports the following features: 1. DataPath will ignore invalid drives or path specifica- tions. 2. DataPath has a very small size. When installed, it uses only 1440 bytes of RAM. 3. DataPath will skip over a drive listed in the DataPath if the drive door is left open. You will have to wait for the disk to time out, however. You will get the normal Abort, Retry, Ignore command if the default drive door is open. 4. THE SOURCE TO DataPath IS RELEASED TO THE PUBLIC DOMAIN! 5. DataPath works on any MS-DOS or PC-DOS system. (Ver- sion 2.0 or higher.) It is not dependent on hardware. 6. DataPath is compatible with CP/M style function calls in MS-DOS for older programs such as dBase II. Page 6 DataPath - GDC Software Technical Details DataPath was written in assembly language and was optim- ized for both small size and fast operation. The source for the program is in the file DP12.ASM. DataPath works by intercepting three different function calls to the operating system. These are 'OPEN', 'FILE SIZE', and 'OPEN FILE HANDLE'. The usual call within MS-DOS now is 'OPEN FILE HANDLE', but some programs use the older functions. Lotus 1-2-3 Version 1A, for instance, uses 'FILE SIZE' to open a file. DataPath also intercepts older CP/M style call to the operating system, converts the calls to MS-DOS calls, and executes accordingly. The dBase II program uses this method. DataPath uses the 256 byte PSP (program segment prefix) that is left resident when the program installs itself. It uses the space for storing the DataPath and for working space. The program logic for DataPath is as follows: 1. If DataPath is not interested in the function, pass it to DOS undisturbed. 2. Try the function. If successful, return to the call- ing program. 3. If the file is to be opened for writing and the /R option (open for read only) is in effect, return. 4. If the path of the desired file is specified, return. If the program knows enough to specify a path, DataPath will not interfere. DataPath WILL search if only the disk drive is specified. 5. Search for the file along the DataPath. If not found, return the error code found in step 2. If found, complete the function and return to the calling program. Page 7 DataPath - GDC Software Limitations Listed below are the known limitations of DataPath: 1. The maximum length of the DataPath string is 118 char- acters. This is due to the 127 character limitation MS-DOS puts on input strings. 2. DataPath cannot be uninstalled without rebooting the system. This should not be a problem because of its small size. DataPath can be disabled by making the DataPath string blank. 3. The DataPath will not accept wildcards. They will be ignored. 4. DataPath will not create aliases for pathnames. 5. DataPath will not automatically search subdirectories beneath the specified directory. References The following magazine article contains information on utilities that do the same function as DataPath: PC Tech Journal - April 1985 - pp 139-145. "File Search Help for PC-DOS" by Arthur A. Gleckler The following magazine article contains general informa- tion on resident utilities: PC World - June 1986 - pp 270-284. "Battle for the Background" by Bruce Owen The following programs perform the same basic function as DataPath. They contain different features, however their basic intent is the same as DataPath. DPath30 - Public Domain - No source FilePath - Commercial - $ 37.50 Scout - Commercial - $ 29.95 SuperPATH - Commercial - $ 39.95 EasyPath - Commercial - $100.00 Page 8 DataPath - GDC Software Disclaimer There is no copyright associated with this program. It is, however, intended for private noncommercial distribution only. You may make copies freely and use the source code in any manner that you wish. Please do not charge anyone for this program. It is free. This software is not warranted in any manner. No guaran- tee is made that the program operates as it was designed. I will not be liable for any damages that may occur by using this program. If you use the program, you agree to this. Any comments, suggestions, or criticisms are welcome. Examples of conflicts with other memory resident utilities or the inability of DataPath to work with a particular program are especially welcome. I can be normally be reached at the following: Telstar Bulletin Board (512) 822-8882 SAHUG Bulletin Board (512) 341-0586 Compuserve ID: 72330,123 If you distribute this program, or a modification of this program, it would be nice for you to acknowledge the source. Bruce Dubbs GDC Software 122 Valencia Dr. Universal City, TX 78148 September 2, 1986 Page 9 DataPath - GDC Software Modification History Version 1.0 - September 2, 1986 - Original release. Version 1.1 - September 18, 1986 - Add /Q, /V, /W, and /R switches. Allow DataPath to be searched if disk drive is specified in ASCIIZ file spe- cification. Version 1.2 - October 9, 1986 - Add /H switch. Improve memory resident check for compatability with other GDC memory resident utilities. Page 10 DataPath - GDC Software Suggestions for use The best way to use DataPath is to organize your disk subdirectories such that the executable and supporting files are on a different subdirectory than the data files. The best example is WordStar. If you put the WordStar executable and overlays in a subdirectory 'WORDSTAR' and have your data files in other subdirectories, the following benefits occur: 1. You can execute WordStar from ANY subdirectory. 2. You do not have to look for your data files intermixed with executable and overlay files. To do this, set the following to execute in the AUTOEXEC.BAT file that executes when you boot MS-DOS. PATH \WORDATAR DATAPATH \WORDSTAR WS This procedure can be generalized to any set of programs and overlays. To keep from setting multiple paths for all searches, a set of batch files can be created such as the following file that executes dBase III. DO.BAT: echo off datapath c:\dbase path c:\dbase dbase %1 path c:\bin;c:\batch datapath c:\bin This example assumes the dBase executable files are in the directory \dbase, the batch file DO.BAT is in the directory \batch, the MS-DOS executable files are in \bin and the data for dBase are in the current directory. For more information on batch files, consult the MS-DOS manual.