On Mon, 2020-05-25 at 20:00 +0200, Liam Proven via cctalk wrote: > On Mon, 25 May 2020 at 05:30, Fred Cisin via cctalk > <cctalk@classiccmp.org> wrote: > > > > > IBMs came with an installable driver called, I think, IBMCACHE.SYS. > This used extended RAM (above 1MB) as a hard disk cache, without XMS > or HIMEM.SYS or any of that. I played with it and was amazed by the > results. I started enabling it by default on customers' machines.
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. There was a *huge* battle within IBM on if it should be released and in order to do so, it was fairly well hidden. > Most > were happy but some had the habit of just turning off -- DOS didn't > really have a shutdown routine. Some, I could train to press > Ctrl-Alt-Del before turning off. Some I couldn't, so I had to disable > the disk cache. 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. > > But for those that could learn and adapt, it made DOS _much_ faster, > and on a 1MB PS/2 Model 50 or 60, it was about the only thing you > could do with the extra 386 KB of RAM before MS-DOS 5 came out. > TTFN - Guy