--- On : Sat, 19 May 2012 15:43:57 -0700, Jack <...@earthlink.net> wrote :

> Given the "high level of responsibility" [Ha-Ha!] taken by the
> VirtualBox creators, it looks as if I will have to add another
> UIDE switch, that disables diskette caching regardless of what
> its other switches tell it to do. 

Jack, if I may chime in... I think you're now contemplating the right step.  I 
can understand your frustration with VB in this instance, BUT imho your 
previous approach has been to ignore a few facts, that have nothing to do with 
that or another emulator or virtualiser : 

On REAL (old) PC hardware, the existence of floppy disk changelines is not 
guaranteed; even if the line is present AND properly connected it MIGHT be 
flaky or not work at all; or the BIOS might not update the bits you expect. 
MS-DOS (and, I presume, good DOS clones as well) will use alternate means and 
kluges to check for media change in the absence of a (credible) change line. 
Your DOS drivers could have been relying on DOS for checking media change, not 
on the BIOS or direct HW interrogation in the 1st place !

Offering the user an option to switch diskette caching off is much better. As 
you are aware, SMARTDRV allows a user to select, disk per disk, not just for 
floppies, to cache or not to cache - and if cacheing, whether to allow delayed 
writes or just write-through.  

> -- UIDE2 has only
> 16 spare bytes before it goes back over a 7K .SYS
> file!   But,
> I shall find a way!

No doubt you will.



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