Detecting inserted floppy drive WAS: Raymond Check discusses MS DOS Floppy Disk Cache

Fred Cisin cisin at
Wed Oct 2 16:57:59 CDT 2019

On Wed, 2 Oct 2019, Ali via cctalk wrote:
> Just wondering if anyone (Chuck, Fred?) knows what is the exact technique referred to in this other post by Raymond?

As I understnd it, they just used a stopwatch and watched a couple of 
their people change disks.
Since it was always 2 seconds or more, they used that as the number.

Chuck, on the other hand, polled the write protect switch every 1/4 
second.  If it changed state, he assumed disk change.
1/4 second assumes that nobody could take out an un-write protected 5.25 
(or write protected 8") in less than 1/4 second, and then later put in a 
different one in less than 1/4 second.

Unless you also have a way to monitor door opening (SOME drives), I have 
an unnecessary worry that on an 8" write protected disk, you could change 
disks.  'course, if the disk is write protected, then you don't need to 
worry bout writing buffers to the wrong disk.

BTW, on "Computer Bowl" quiz show, NOBODY on Bill Gates' team could answer 
the question of WHERE the write protect notch is on an 8" disk!

Grumpy Ol' Fred     		cisin at

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