SMART PROMPT Notice of Copyrights ------------------------------------------------------------------------ This file and the enclosed SMARTPMT.COM file are copyright 1993 by Steve Gibson, Irvine, California, USA. *** ALL RIGHTS RESERVED *** These files may be freely distributed and used for any purpose whatsoever so long as they are kept together and not modified in any way. ------------------------------------------------------------------------ The enclosed program, SMARTPMT.COM (Smart Prompt) is Steve Gibson's tiny (336 resident bytes) TSR which helps to prevent drive (and especially DoubleSpace) partition corruption in DOS 6.0 systems. When returning to the DOS system prompt with hard disk cached data not yet completely written to any drive, SMARTPMT triggers immediate disk cache writing and briefly suspends the return of the DOS system prompt until Microsoft's Smart Drive disk cache has finished all writing. SMARTPMT.COM requires only a tiny bit of RAM space yet it makes the DOS 6.0 prompt completely safe again. This program was originally written to supplement Steve Gibson's weekly InfoWorld Magazine TechTalk column of May 17th, 1993. The text of that column is provided below for additional background: ******************************************* Steve Gibson's TechTalk Column for InfoWorld's May 17th, 1993, Issue # 20 ******************************************* Last week I alluded to the belief that I knew what was causing this "DoubleSpace nuked me after ten days!" behavior which seems to be so prevalent. Also last week, InfoWorld's Test Lab magician, Kevin Strehlo, who's been pursuing many DOS 6.0 loose ends, indicated that he had determined that many of the problems InfoWorld had experienced with "DoubleSpace" turned out to be related to the write deferring behavior of SmartDrive. I believe that he hit the nail squarely on the head! The "loaded gun" (which is all too often found to be smoking) that Microsoft mistakenly placed into DOS 6.0 is their default installation of SmartDrive 4.1 with its "lazy writing" option active. As you may know, lazy writing means that the system's hard disk cache buffers data which needs to be written to the hard disk drive so that the operating system and its applications don't need to wait around for this writing to occur. The cache intercepts the system's write requests, placing the data quickly into temporary RAM memory, and immediately returns control to the application or operating system. At some later point, after the system and the hard disk drive have been idle for a while, the system's hardware clock "wakes up" the cache and triggers a gradual "flushing" of its buffers. I don't believe that write deferring is a bad thing at all, in fact I believe it's a very worthwhile technology which we're as stuck with as we are with compression, but with deferred writing comes some clear responsibility. Microsoft's automatic installation of SmartDrive write deferral in DOS 6.0 completely fails to disclose the inherent dangers of this technology. It took us quite a while to explain to the many tens of millions of computer users why they could not simply turn the computer off while they were still within Wordperfect or Lotus after printing their document. We also had to explain that they really should not press that little red button on the front of the machine without trying a number of other things first. The continual accumulation of lost hard disk cluster chains only ceased once they had all finally learned to first save their documents then exit Wordperfect, returning to the safe DOS prompt BEFORE reaching down to flip the power switch of their machine. Then one night without notice, DOS 6.0 was installed upon their system and this once fail-safe behavior became a recipe for guaranteed failure and, when coupled with DoubleSpace, assured hard disk data loss. Check it out for yourself: After DOS 6.0's default installation, and depending upon the speed and performance of the host computer system, if you exit to DOS from within an application, responding "YES" to the prompt to "Save Modified Document", on your way out, you'll receive the DOS prompt immediately, while after a short pause the light on the system's hard disk will begin to flicker as it only then begins writing the document out to the hard disk drive. How would you like to turn the computer off right then? No? Well, across the planet this is the danger which DOS 6.0 has created for its trusting users. What can you do? I can suggest only three cures for this dilemma: You could override SmartDrive's default behavior, in the process losing the performance benefits it delivers. Or you could reeducating all those tens of millions of computer users about this NEW danger and of their new responsibility to prevent disaster. Or you could install the tiny TSR I wrote for the purpose, which triggers an immediate flushing of all pending SmartDrive writes when returning to DOS and suspends the return of the DOS prompt until the cache has been completely cleaned out. It makes the DOS prompt safe once again. I call it "SmartPrompt" and I wrote it for you. It occupies just 336 bytes of memory, is loadable high or low, and as far as I've been able to tell it completely solves the problem of this "early return" of the MS-DOS 6.0 prompt when under the influence of the otherwise very nice and high performance SmartDrive 4.1 hard disk cache. You can find it on Compuserve or from my BBS at (714) 362-8848. I hope it saves some data! -30- README.TXT file ends ------------------------------------------------------------------------