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Software Vault: The Gold Collection
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Software Vault - The Gold Collection (American Databankers) (1993).ISO
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README.TXT
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1993-05-19
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106 lines
SMART PROMPT
Notice of Copyrights
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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
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