ImageDisk under Win2k (was: Thanks again, Dave!)

[dave04a at dunfield.com]

> Rumor has it that Dave Dunfield may have mentioned these words:
> 
> This discussion is purely for academics... ;-)

Indeed

> >IMD needs:
> >  - unrestricted access to the floppy disk controller hardware.
> Which the HAL doesn't provide. :-/

I haven't looked into the gory details, however I expect that "HAL"
just virtualizes an FDC and translates it's operations to the standard
Win28 floppy driver - which means it works only as long as you don't
configure the FDC in any way that the Win2k driver does not.

I also wouldn't trust the virtualization to be "wonderful" in terms of
real-time emulation (for example, I've seen the virtual serial port of
the XP dosbox take up to 10 seconds to report a character received
(needless to say this breaks lots of stuff).


> >  - Nobody else messing with the FDC hardware
> 
> That might be possible, but...
> 
> >  - /interrupts while it is active.
> 
> There's certainly no guarantee for that.

Under DOS, I take over the interrupt, and since I alone am
controlling the FDC, I only get interrupts I expect - under Win2k,
I expect you can't get a "real" interrupt vector (only a virtual one),
and diddling with the chip may cause Win2k to see an interrupt and
go poking around on it's own ...

 
> >  - to not be held-up while some other task decides to hog the CPU for
> >    a little while (there are real-time critical aspects to the analysis 
> > phase)
> 
> At least on this, I could *guarantee*... I have a dual-processor box 
> (2xAthlon MP 2600+), so any processes wanting to hog 1 CPU won't affect the 
> other. ;-)

Are  you sure? - you might have a "spare" processor, but what I was really
getting at is "an OS that doesn't decide not to dispatch you for a while". I'm
not convinced you can guarantee this under any flavor/configuration of winblows.
 

> >Btw - you can reduce the space requirements a lot by using a KVM
> >switch . (I put one on my test-bench last year and eliminated two
> >monitors/keyboards - very handy). 
> Yup. Got one on my desk at work - but my space & power requirements at home 
> for the most part belie the area for a second micro-tower, and KVM switches 
> don't help with the CoCo[1] or Amiga problems... ;-)
> 
> I should take a picture of my desk

I'd respond with a photo of my basement (all the machines depicted on my web site
are there) - needless to say, they are not all set up and accessable at the same
time (can you say "optimized for storage")!

Regards,
Dave

-- 
dave04a (at)    Dave Dunfield
dunfield (dot)  Firmware development services & tools: www.dunfield.com
com             Vintage computing equipment collector.