25 May
2020
25 May
'20
11:28 a.m.
On Mon, 25 May 2020 at 20:22, Guy Sotomayor <ggs at shiresoft.com> wrote:
I hadn't thought about IBMCACHE.SYS in *years*. I wrote it in its
entirety (there's even a patent that covers some of its operation). I
was in an AdTech (Advanced Technology) group at the time and was
looking at how to make disk operations faster in DOS at the time when I
came up with the idea.
Oh my word! Well I thank you for it. It helped a very great deal and
made dozens of users of rather expensive IBM PS/2s in the Isle of Man
very happy for a while in the late 1980s and early 1990s. :-)
There was a *huge* battle within IBM on if it should
be released and in
order to do so, it was fairly well hidden.
I can believe that! I think I read of it in a magazine and thought
"never! I'd know!" -- so I looked and there it was.
There was a switch on config.sys statement for
IBMCACHE.SYS to turn off
the write-back cache (e.g. writes would always go straight to disk).
As I recall, there was a 30 second timer for the writeback cache so
that if a disk block was "dirty" for more than 30 seconds it would get
flushed to disk.
Yes, both true. I think I may have used the write-through switch for
some people, but ISTR it reduced performance a little bit. Just
teaching people to be a bit more patient was sometimes hard -- after
all, this was a tool that appealed to the impatient!
I think for them it was easier to teach them to press C-A-D and then
wait for the RAM check before turning off.
Or hit C-A-D, let it boot all the way, then turn it off!
Great bit of work, if I may say so!
--
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