history is hard (was: Microsoft open sources GWBASIC)

Liam Proven lproven at gmail.com
Mon May 25 13:28:47 CDT 2020

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!

Liam Proven – Profile: https://about.me/liamproven
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