[openMSX-devel] [ openmsx-Feature Requests-834742 ] Fast disk/tape reading

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Feature Requests item #834742, was opened at 2003-11-02 23:16
Message generated for change (Comment added) made by manuelbi
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Category: General/misc
Group: None
Status: Closed
Priority: 5
Submitted By: Nobody/Anonymous (nobody)
Assigned to: Manuel Bilderbeek (manuelbi)
Summary: Fast disk/tape reading

Initial Comment:
A setting in openmsx that sacrifices accuracy for reading speed of 
disk images and tape images. A bit like on RuMSX, where a diskimage 
is read as fast as the emu can handle it, and not, like on openMSX, 
as fast as the emulated floppy disk controller allows. It'd be very nice 
to make this an option that can be turned on/off with a hotkey (with a 
default of 'off' so software won't break because the emulation is less 
accurate)

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>Comment By: Manuel Bilderbeek (manuelbi)
Date: 2005-11-06 11:36

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> using 1000% (or any other speed factor) isn't always that 
> good. If you have for example background music, throtteling 
> the speed is quite annoying. Besides, loading takes longer 

Yes, but these cases are rare. The feature is turned off by
default. If the user wants it, he can turn it on and if it
annoys him, he can turn it off.

> than the patched diskrom anyways. For the user, the patch 
> cas files is much better, fast loading and no side effects on 
> sound. I fully agree with mth though that the patched disk 
> rom has some problems and from an accurate emulation 
> point of view its not good. 

Indeed, this will always be faster. But we're just not going
to reimplement this for now.

> In blueMSX we support the automatic throtteling like mth 
> describes. Some users like it and some don't. Personally I 
> don't like it and I prefer to have a shortcut key so I can 
> control the throtteling myself. But we've had users that has 

Well, we have both now. Why don't you like it?

> requested to put the patched diskrom back because its more 
> convenient for the user.

I don't think the patched disk ROM makes much of a
difference compared to the feature I just implemented. But
for cassette it will always be faster to use  a patched BIOS
with CAS files.

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Comment By: dvik (dvik)
Date: 2005-11-06 02:38

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using 1000% (or any other speed factor) isn't always that 
good. If you have for example background music, throtteling 
the speed is quite annoying. Besides, loading takes longer 
than the patched diskrom anyways. For the user, the patch 
cas files is much better, fast loading and no side effects on 
sound. I fully agree with mth though that the patched disk 
rom has some problems and from an accurate emulation 
point of view its not good. 

In blueMSX we support the automatic throtteling like mth 
describes. Some users like it and some don't. Personally I 
don't like it and I prefer to have a shortcut key so I can 
control the throtteling myself. But we've had users that has 
requested to put the patched diskrom back because its more 
convenient for the user.

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Comment By: Manuel Bilderbeek (manuelbi)
Date: 2005-11-05 00:07

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This is now experimentally implemented via the
'fullspeedwhenloading' setting. For diskdrive it goes to
full throttle in case the diskdrive motor is on (which is
far from ideal) and for tape when the motor is on AND a
cassette is present.

Please reopen when the feature gets scrapped again due to a
bad implementation :P

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Comment By: Maarten ter Huurne (mthuurne)
Date: 2003-11-05 02:23

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In the past we had the patched disk ROM, which could load very fast, 
but was inaccurate. This is not a theoretical inaccuracy either: there 
are several games (Aleste Gaiden, Fray, Xak 3) that break if the 
emulated MSX is frozen during loading. So I don't like this solution. 
 
Fortunately, there is an alternative. We could speed up openMSX 
during loading, either by a fixed factor (speed 1000%), or by turning 
off throttle. For this to work, we need to detect when loading occurs 
(both disk and tape) and to be able to really speed up openMSX (see 
bug #836168). Speed up during loading has the advantage that from 
the perspective of the emulated machine, everything is 100% 
accurate; the difference is only visible to the user. 
 

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