Hxc Rev3: track change too slow?

HxC Floppy Emulator on Amstrad CPC support
Targhan
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Re: Hxc Rev3: track change too slow?

Post by Targhan » Thu Oct 01, 2015 9:23 am

Thanks for the firmware. However, using it means that the users will also have to use it, so it is not really doable...

But I don't understand why you talk about "head teleportation". I don't know much about real hardware timings, but how long does it take to read one size-2 sector? This is the time I use to move the head. Plus the GAP the beginning of the track, plus the gaps at the end of the previous one, shouldn't it be enough? In "my" format, the first sector is not read when the head comes to the track, so it should have enough time to be ready for the second sector! Anyway, once again, what I am doing is really reliable on a CPC.

Jeff
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Re: Hxc Rev3: track change too slow?

Post by Jeff » Wed Oct 07, 2015 8:04 pm

Targhan wrote:...but how long does it take to read one size-2 sector? This is the time I use to move the head. Plus the GAP the beginning of the track, plus the gaps at the end of the previous one...
About the time to read a sector : the track is shifted by one sector, so when you read the last sector you make a step, then you got directly the fisrt sector to read ! the only space between the last and the first sector is the sector gap !

About the start & end track gap, you are reading from sector 177 up to 186 then jumping to the next track. The sector 186 position is different on each track so you can't take the start and end track gaps.

am i missing something ?

TFM
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Re: Hxc Rev3: track change too slow?

Post by TFM » Wed Oct 07, 2015 10:18 pm

Hi guys,

What is a 15 ms settling time?

Even with the slow 3" drives of the CPC the step rate is with 10 ms on the safe side. 3.5" and 5.25" usually work with 4 ms.

When reading the last sector a track (that's the last sector I do read before I move the head to another track) without an error I tell the FDC to step to the next track, there I do read a sector ID, and then the next sector which is to be found in physical order.

What ever a settling time is has probably no impact, because after moving the track the first thing I do is to read a sector ID.

This works very quick on CPC (DS, 80 Trk, Vortex format), but is an order of magnitude slower on HxC.

IMHO some time constant in the HxC firmware is too big.

EDIT: What matters is that the HxC simulates reality, not floppy-disc-producer-paperwork, no? :-)

Jeff
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Re: Hxc Rev3: track change too slow?

Post by Jeff » Wed Oct 07, 2015 11:25 pm

TFM wrote: What is a 15 ms settling time?
Mostly mechanical head stabilization + AGC (automatic gain control) circuit stabilization.
BTW lots of drives "gate" the data line during the settle time and don't output anything.

http://eab.abime.net/showpost.php?s=480 ... ostcount=9
http://eab.abime.net/showpost.php?s=480 ... stcount=14

TFM wrote: EDIT: What matters is that the HxC simulates reality, not floppy-disc-producer-paperwork, no? :-)
It does, and if you don't emulate correctly the settle time you make lots of amiga trackloader going crazy ;).

Anyway if you want you can take the cheater firmware there :

http://torlus.com/floppy/forum/viewtopi ... 592#p11592

Jeff
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Re: Hxc Rev3: track change too slow?

Post by Jeff » Thu Oct 08, 2015 8:26 am

Step and Settling time increased to 16ms for all machines (and not only Amiga) :

http://hxc2001.com/download/floppy_driv ... rmware.zip

Seems to load faster ;)

So the HxC wasn't too slow, but too fast for the CPC routines.
Waiting for feedbacks.

Targhan
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Re: Hxc Rev3: track change too slow?

Post by Targhan » Mon Oct 12, 2015 10:40 pm

About the time to read a sector : the track is shifted by one sector, so when you read the last sector you make a step, then you got directly the fisrt sector to read ! the only space between the last and the first sector is the sector gap !
Yes, you missed something indeed! I'm glad we could point that out :). Let me use a simplified schematic.
Track 0: #a1 #a2 #a3 #a4 #a5 #a6 #a7 #a8 #a9 #aa
Track 1: #aa #a1 #a2 #a3 #a4 #a5 #a6 #a7 #a8 #a9
...

- On track 0, I read #a1 to #aa.
- Goto Track 1.
- I give the order to read #a1. HOWEVER, the track is still moving/is not ready. *If* I wanted to read #aa on Track 1, *I would miss it* because the head is NOT ready yet, so it would have to wait a full turn. HOWEVER, I want to read #a1. By the time #a1 comes under the head, the head has finished its motion and is ready! So you see, there is no "head teleportation". I just shift the sectors so that the head has enough time to move and settle on the new track.

As a test, I created a format that shift the sectors of 2 slots, not 1. Like this:
Track 0: #a1 #a2 #a3 #a4 #a5 #a6 #a7 #a8 #a9 #aa
Track 1: #a9 #aa #a1 #a2 #a3 #a4 #a5 #a6 #a7 #a8

It IS working on the HxC. But it's 1/10 slower than the speed I expect with the first format shown here.

Is it clearer now?

Thanks a lot for your time.

Jeff
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Re: Hxc Rev3: track change too slow?

Post by Jeff » Mon Oct 12, 2015 11:58 pm

Have read my last post ?
Have you tried this firmware ?

Targhan
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Re: Hxc Rev3: track change too slow?

Post by Targhan » Tue Oct 13, 2015 12:04 am

I over-read it, but is it an official release (I mean, will ALL the users use this specific firmware?)?.

Targhan
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Re: Hxc Rev3: track change too slow?

Post by Targhan » Tue Oct 13, 2015 12:17 am

Ok, I used the last firmware and... it works! That's great.

Thanks a lot for your great work. When do you think the beta will be released?

Jeff
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Re: Hxc Rev3: track change too slow?

Post by Jeff » Tue Oct 13, 2015 7:31 am

Targhan wrote:Ok, I used the last firmware and... it works! That's great.

Thanks a lot for your great work. When do you think the beta will be released?
This beta is already available at the download pages.

Targhan
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Re: Hxc Rev3: track change too slow?

Post by Targhan » Tue Oct 13, 2015 10:10 am

Great. Could you explain to me why exactly you said the "HxC was too fast", and how the new value made our loading track actually faster? Thanks.

TFM
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Re: Hxc Rev3: track change too slow?

Post by TFM » Fri Oct 30, 2015 11:58 pm

Thank you very much for the update, will test tonite :-)

TFM
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Re: Hxc Rev3: track change too slow?

Post by TFM » Thu Nov 12, 2015 11:59 pm

Hi!

Tested the new firmware, but sorry, no change. Loading is still terribly slow.

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Re: Hxc Rev3: track change too slow?

Post by Jeff » Sat Nov 14, 2015 3:00 pm

TFM wrote:Hi!

Tested the new firmware, but sorry, no change. Loading is still terribly slow.
Seriously, are you kidding to me ? :? Tested here, all is fine. And Targhan have confirmed that the speed was fine some weeks ago.

Some questions to have some valuable information about your test case :
Which HxC, Which CPC, Which image / software ? (Share the DSK and the HFE files !), At which moment into the software ?

Which firmware have you used exactly ?

You must use this one :
http://hxc2001.com/download/floppy_driv ... rmware.zip

V1.8.6.15a

TFM
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Re: Hxc Rev3: track change too slow?

Post by TFM » Mon Nov 16, 2015 10:49 pm

Of course I used this software. My HxC is Rev C from Lotharek.

Targhan uses custorm format. I use standard Vortex format (80 Trk, DS, 704 KB, 9 sectors a 512 KB).

Maybe you need to adjust a little more.



You can use this DSK image for testing:

http://futureos.cpc-live.com/files/DarthVader.zip

Please compare loading speed from real 3.5" disc on real CPC6128 with HxC. Needs 512 KB RAM.

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