Re: [hatari-devel] fdc test for real hardware

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On 22/09/2013 23:11, Roger Burrows wrote:
On 22 Sep 2013 at 22:55, Nicolas Pomarède wrote:

On 22/09/2013 21:49, Roger Burrows wrote:
On 22 Sep 2013 at 19:32, Nicolas Pomarède wrote:

Could someone with a working STF/STE test this program and post the
results ? I need results from different machine to measure the relation
between RPM and index duration.

On my 1040STF:
(details omitted)

Thanks for your results ; are these pal or ntsc model ?

These are with an NTSC model.


After converting those numbers to RPM (taking cpu clock into account), I get very stable RPM for STF, but STE's ones are sometimes changing significantly for no apparent reason :

my 520 STF PAL : 299.6 - 299.7 RPM

roger's 1040 STF NTSC : 300.3 RPM

roger's 1040 STE NTSC : 300.78 RPM but sometimes 299.19 RPM

ragnar76's 1040 STE PAL : 300.86 RPM but sometimes 299.26 RPM

For STF, index time is stable, 1.88% or 1.94 % of total revolution's time

But for STE, identical RPM sometimes give different index time (for example 300.78 RPM, but 1.35%, 1.22%, 1.09%), which is quite odd. Maybe there's something different in the STE wiring for the FDC, but that was not my impression when looking at the board's schematic. Or maybe it's just because drive and/or floppy are old.

Having different RPM between machine is not a problem, it depends on the drive's initial seting ; but once the motor is spinning, RPM should be fairly stable, which is not the case for those STE.

Anyway, I don't know any program that rely on such high precision for the duration of the index signal. I will use the STF's ones as they're always stable.


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