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Text File | 1990-05-13 | 18KB | 411 lines

A Critical Error Handler Copyright 1990 by TANSTAAFL Software Version 1.10 May 13, 1990 CRITTER is a terminate and stay resident critical error handler. CRITTER replaces DOS's "abort, retry, ignore" message with a pop-up window that restores the screen when finished processing the error. This version of CRITTER adds an automatic response, where the user can specify a response to be supplied at a certain time after the error occurs. Possible responses can include Abort, Retry, Ignore, Fail, Soft reboot, or Hard reboot. Instructions For Use -------------------- At some point in your AUTOEXEC.BAT file, type in the command 'CRITTER'. The command line parameters below may also be inserted. CRITTER [/U] [/M] [/S] [/Boptions] [/Toptions] [/Noptions] [/Aresponse] [/Otimeout] /U Unload the TSR. Like all TSR's that allow themselves to be unloaded, this feature only works if this TSR was the last one loaded. This TSR will unload correctly from high DOS RAM (above 640K). /M Monochrome switch. This allows correct display on monochrome monitors connected to color display adapters. /S Sound switch. This turns off the beep when an error is detected. Normally a beep is generated to signal an error. /B Allows setting border colors (see below). /T Allows setting title colors (see below). /N Allows setting normal text colors (see below). /A Allows automatic response to an error. Response can be one of the following: Response Action Response Action --------------------------------------- A Abort R Retry I Ignore F Fail S Soft reboot H Hard reboot /O Allows user to specify the number of seconds to wait for a user response before triggering the automatic response specified by the /A option. If /A is specified and /O is not, no screen will be shown and the automatic response will take effect immediately. Color Options ------------- Each color command is followed by characters that determine the color to use. Each color is designated by a single character, as indicated by the chart below. If the character is in upper case, it sets the background color. A lower case character sets the foreground color. Adding a [+] to the string makes the fore- ground color bright, while adding a [*] makes it blink. Color commands may be used in any order. Color Character Color Character --------------------------------------------------------- Black K, k Blue B, b Green G, g Cyan C, c Red R, r Magenta M, m Yellow Y, y White W, w Bright + Blink * Examples /bwK border is dim white on black /ty+*R title is blinking bright yellow on red /ncB text is cyan on blue Automatic Response ------------------ The automatic response feature allows the user to specify a default action and timeout duration. If a critical error occurs and the timeout value is specified, CRITTER shows the error window and waits for a key to be pressed as usual (A-abort, R-retry, etc). The window will now contain an extra countdown timer line. If the user does not respond before this count reaches zero, then the automatic response is triggered. All four possible responses to the error are supported (Abort, Retry, Ignore, and Fail). Not all errors support all responses, however, Abort is always enabled, as is Fail on DOS versions 3.x and 4.x. The automatic response unit can also reboot the computer as a default response. Either a hard (reset) or soft (Ctrl-Alt-Del) reboot can be triggered. This is useful for network or BBS systems that must run unattended. The soft reboot feature does not work consistently on some PCs. This seems to be caused by minor BIOS incompatibilities. Before relying on a soft reboot, test it once to insure it works on your computer. Critical Error Handler Theory ----------------------------- Critical errors are caused by hardware errors, generally in disk drives. These errors may be minor (such as printer out of paper, or drive door open) or fairly catastrophic (like a scrambled FAT or dead hard disk). A critical error can be caused by virtually any DOS call EXCEPT interrupts 25h and 26h (Absolute Disk Read & Write). A critical error is associated with a device and can be either a block device (disk drives) or a character device (printer, keyboard, clock, etc.). Each time the error handler is called, parameters are passed that indicate which error occured and where it happened. The DOS critical error handler is entered via software interrupt 24. DOS will allow a program to replace the DOS critical error handler with its own, but only for the duration of program execution. When the program exits, DOS replaces the address of the program's handler, routing all further critical errors to DOS. CRITTER patches the resident portion of COMMAND.COM so that CRITTER has control of critical errors. The disk file COMMAND.COM is NOT changed. Due to the unusual way DOS handles INT 24, CRITTER can only be unloaded with the /U command line option. If a TSR manager is used (such as MARK and RELEASE), the resident portion of COMMAND.COM will not be "unpatched" and the next critical error will cause the computer to loop until reset. The CRITTER critical error handler will give the following information: Error (DOS) Write protected disk Unknown unit Drive not ready Unknown command CRC error in data Bad drive request Seek error Unknown media type Sector not found Printer out of paper Write fault Read fault General failure Sharing violation Lock violation Invalid disk change FCB unavailable Sharing buffer overflow Error (Network) Network busy Network device no longer exists NetBIOS command limit exceeded Network adapter hardware error Incorrect response from network Incompatible remote adapter Print queue full Not enough space for print file Print file was deleted Network name was deleted Error Cause Read operation Write operation Error Location System area File Allocation Table Directory Data area Internal copy of FAT Other Info (char) Device name (block) Drive designator Possible responses to a critical error are Abort, Ignore, Retry, or Fail. Not all responses are possible at all times -- it depends on the error and the version of DOS. The CRITTER software enables only those responses that DOS will allow at the time. Test Results ------------ Unfortunately, this software is hard to completely test. Several easy errors can be generated. These include the write protect error, the drive not ready error, the paper out error, and the read & write faults. Other errors could be tested if they were physically produced, such as unplugging the clock chip or crashing the hard disk (not recommended). CRITTER was tested with various DOS versions from 2.1 up through 4.01. It was tested with various programs and was found to allow the tested program to install its own error handler for the duration of its execution. Upon return to DOS, CRITTER continued to handle errors correctly. For those text mode programs that don't install their own error handlers, CRITTER takes care of it for them. CRITTER should work with all programs (either by working or by getting out of the way); it has been tested with the following programs: Brief 3.0 Dbase III Plus Quattro Professional Paradox 3.0 Procomm Plus PC Tools 5.5 & 6.0 Windows 2.1 Microsoft C 5.1 Turbo C 2.0 Microsoft Assembler 5.1 CRITTER does not work in the DOS compatibility box under OS/2. In the event that the display is in graphics mode, CRITTER will use the DOS handler. This will result in the screen being scrolled. Most programs that use graphics modes do contain their own critical error handlers. Files In This Archive Include: ------------------------------ critter.doc (this file) critter.exe CRITTER program Future Enhancements ------------------- A version of CRITTER for OS/2 is both desirable and difficult. The way OS/2 handles critical errors does not make a TSR such as CRITTER a viable solution. However, other avenues are currently being pursued. Graphics modes are another obstacle. Currently, CRITTER defaults to using the existing DOS critical error handler in all graphics modes. Being able to accurately detect the current graphics mode and display over graphics (and restore) is probably not possible, although it is being researched. Later versions of MS-DOS (3.0 and above) include an interrupt to get extended error information. The next version of CRITTER is likely to include this extended information. All users are invited to suggest enhancements. See below for communications addresses. Terms And Conditions -------------------- You may use this software freely in any non-military environment. You may distribute this software freely as long as the archive file contains all of the files mentioned above. This software (Version 1.1) expires after December 31, 1990, and will display a message to that effect. Once purchased, a registered version will not have this restriction. The following purchasing terms are available: Standard Registration $ 20 Latest version, disk size of your choice. Shareware Distribution License $100 Special version for shareware authors wishing to distribute CRITTER with their products. Allows unlimited distribution. Source Code in C and Assembler $200 * Includes the unusual tricks we used to get CRITTER to work and well-commented source code. Commercial Distribution License $300 Special version for authors of commercial software, allows unlimited distribution. With source code. And of course, if your mailing address is in Colorado, include sales tax (currently 7.1%). If you desire a site license or are a special interest group, contact the authors. * Microsoft C v5.1 and the Microsoft Macro Assembler v5.1 are required to assemble and/or compile the source. Communications -------------- We may be reached by the following methods for feedback: on GENIE mail address TANSTAAFL (for Dana Cline) on Prodigy mail address NCDC07A (for Dana Cline) on CompuServe mail address 74606,525 (for Dean McCrory) by phone (303) 989-7389 After 8 AM and before 10 PM MST (Thanks!). I do have an answering machine, which has an unlimited message length. I am generally not in during the day (I have to work, too). by mail Dana W. Cline TANSTAAFL Software P. O. Box 260075 Lakewood, CO 80226 Feedback of all types is appreciated. Disclaimer ---------- The authors claim no responsibility for any damages caused by the use or misuse of this product. This product is distributed "as is" with no warranty expressed or implied. The authors will not be responsible for any losses incurred, either directly or indirectly, by the use or misuse of this product. The authors reserve the right to make modifications at any time. Prices are subject to change without notice. Thanks to: ---------- Dean McCrory, for making CRITTER go TSR! Holly Miller, for much help on this manual. Jerry Pournelle, for continually harping about the drawbacks of MS-DOS. Floyd Pretz, for suggesting the automatic response feature. Information Sources: -------------------- MS-DOS Programmer's Reference, from Microsoft Press MS-DOS Developer's Guide, from the Waite Group Microsoft C 5.1 Manual, from Microsoft MS-DOS Functions, from Microsoft Press Trademarks ---------- Because of the nature of this manual, numerous software products are mentioned by their trade names. In most, if not all, cases these designations are claimed as trademarks by the respective companies. Order Form TANSTAAFL Software NAME: ______________________________________________________ COMPANY: ______________________________________________________ ADDRESS: ______________________________________________________ ______________________________________________________ CITY: ______________________________________________________ STATE: ________________________ ZIP CODE: _________________ PHONE: ______________________________________________________ E-MAIL ADDRESS: _______________________________________________ WHERE DID YOU RECEIVE CRITTER? ________________________________ ________________________________________________________________ DISK SIZE NEEDED: [ ] 3-1/2 [ ] 5-1/4 COMMENTS: _____________________________________________________ ________________________________________________________________ ________________________________________________________________ Basic Registration @ $ 20.00 __________ Shareware Distribution License @ $100.00 __________ Source Code in C and Assembler @ $200.00 __________ Commercial Distribution License @ $300.00 __________ Colorado sales tax @ 7.1 % __________ Non-US Shipping @ $5.00 __________ (Payments must be in US Dollars, US bank) TOTAL: $__________ Checks or money orders only. Cash is accepted but discouraged. Absolutely no company P.O's! Remit to: Dana W. Cline TANSTAAFL Software P.O. Box 260075 Lakewood, CO 80226 Version History --------------- Version Date Features / Bug Fixes ---------------------------------------------------- 1.00 04/26/90 Original release. 1.10 05/11/90 Automatic response and timeout feature added.