10 Sep
2012
10 Sep
'12
6:36 a.m.
On 9 September 2012 17:03, Dave McGuire <mcguire at neurotica.com> wrote:
On 09/09/2012 11:27 AM, Liam Proven wrote:
I taught people to do Ctrl-Alt-Del and wait for the BIOS screen,
*then* power off.
Umm...did MS-DOS hook that interrupt and tell smartdrv to flush its
buffers? I don't recall it having done so. If it didn't, that practice
did absolutely nothing. (sorry)
AFAIK, yes. I believe I found the tip in a magazine somewhere, there
being no WWW in those days. If you hit C-A-D there would sometimes be
a brief pause and a spurt of disk activity, /then/ the PC would
reboot.
Before MS-DOS 5, IBM also used to include a disk cache driver for DOS
with some of the PS/2s. It was documented, but not much or well. It
was a small .SYS driver to be loaded in CONFIG.SYS and it gave a
/very/ significant boost in performance. Great in the era of 286s and
386s running DOS 3.3 or 4.01, with 1MB or so of RAM and no use for it
without expensive 3rd party utilities such as QEMM.
IIRC the IBM cache actually displayed a message about flushing buffers
if you pressed C-A-D at the DOS prompt.
Many years later, running a VAX network in the mid-1990s, I was amazed
to discover that VMS did not include a disk cache. It was a
/seriously/ expensive extra - thousands of pounds - but batch
performance went through the roof when I tried a time-limited demo of
one. We bought it PDQ.
> 3.10 also installed SMARTDRV, (misconfigured to
enable write cacheing,
> altered write sequence, and return to DOS prompt without first writing the
> buffers).
I was always careful, trained my clients to be, and never had a problem.
Careful would not protect you if you had a disk write error during delayed
writes (you were slightly lucky), but it WOULD NOT protect you from
turning off the machine before writes after it came back to the prompt on
exiting a program. "I'm DONE! SAVE. EXIT. At the prompt? Hit the power
switch!" Agood reason for implementing the "shutdown procedure"! Yeah. That's sorta analogous to people
preferring IDE because it's
"simpler" because it "doesn't need all those silly terminators and
stuff". It actually DID need terminators...but they were never
implemented due to a stellar combination of cheapness and cluelessness.
Terminators on IDE? Really?
--
Liam Proven ? Profile: http://lproven.livejournal.com/profile
Email: lproven at cix.co.uk ? GMail/G+/Twitter/Flickr/Facebook: lproven
MSN: lproven at hotmail.com ? Skype/AIM/Yahoo/LinkedIn: liamproven
Tel: +44 20-8685-0498 ? Cell: +44 7939-087884