Gotek With Sequential Prophet 2000

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apprenticemart2
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Joined: Tue Feb 21, 2012 3:26 pm

Gotek With Sequential Prophet 2000

Post by apprenticemart2 »

I've been testing a Gotek with my Prophet 2000. It will work but it's not perfect.

I can load an image and save to an image. Loading is normal speed but saving is slower than an actual floppy. Having a faster usb stick makes a small difference to the saving speed but the difference isn't particularly large between a fast or slow memory device.

If I try to format an image it will fail and then that image is corrupted and will no longer work. I can select another image from the usb that I haven't tried to format and that will load OK. Trying to format an image doesn't work but no problem, just save and load to existing images instead, just remember not to format.

These problems can be worked around but the annoying problem is on power-up.

When you switch on the Prophet 2000 it looks for a disk in the drive. If there's a disk it loads it, If there isn't a disk it initialises itself and loads some internal sound patches. No problem.

But with the Gotek drive installed the Prophet 2000 doesn't initialise properly. The internal patches aren't loaded if there isn't a disk and it's as if the Prophet 2000 hasn't detected it's own RAM so it can't produce any sounds (it hasn't initialised properly)
With a usb stick installed in the Gotek on power up it will find a disk image and load it but again, because the Prophet doesn't initialise properly no sounds are produced.

The way to make it work is to power up the Prophet with no usb stick attached and wait for it to initialise (play some keys
to hear there's no sound) , then power off and about 3 seconds later power up again. This time the Prophet 2000 will initialise properly (load internal sounds) and then you can plug in your usb stick. If you wait too long to power back up it will again not initialise properly.

Something about the Gotek on power-up is not behaving like a real floppy drive in a way that the Prophet 2000 likes.
How does the Prophet 2000 check the drive for a disk, is it using the write protect line to detect a disk and maybe this isn't set correctly with the Gotek on power-up?

I have tried to have the Gotek powered up before I apply power to the Prophet 2000, and afterwards, I have tried to play with the reset hold circuit of the Prophet 2000 the hold the processor in reset for longer in case that was the problem but it makes no difference.

Is pin 7 on the ST32 still used for reset with the new firmware, is it 5 volts tolerant, would hooking up a wire from the Prophet 2000 reset circuit help synchronise the two devices in some way if this is a problem? (for experimentation)

I'm going to try to use a scope to see if I can detect what's happening.

I'm using the images from the quick start folder but I had to make my own config file for the Gotek.

Cheers
Martin

apprenticemart2
Posts: 9
Joined: Tue Feb 21, 2012 3:26 pm

Re: Gotek With Sequential Prophet 2000

Post by apprenticemart2 »

Well, I can't get this to be detected on first power-up by the Prophet I have to power cycle every time. Not keen on that so I would advise on using something else in the Prophet 2000.

On power-up with a real floppy drive but no disk in the drive there is some serial/clock coming from the floppy drive into the 1770. Maybe this data is important to help the Prophet initialise properly first time round on power up.

The gotek drive does nothing with no usb, or with usb and just the cfg file on it.
The transmission time from power-up to transmit data is slower on the gotek. I tried to add some extra capacitance to the reset circuit of the Prophet to see if I could change the timing but this did nothing. Also manually resetting the prophet won't make it detect the gotek either.
There's also a high, low to high transition on the wprt pin on power up with the gotek drive installed but the real floppy drive doesn't do this at all. I thought this might be the cause so cut the trace on the gotek and let the wprt pull itself high so there was no transition but this didn't do anything.

So I suppose something must come out of the floppy drive on power-up that the Prophet expects to see and the gotek doesn't produce this? It works properly every time with an original floppy disk installed.

Martin

Jeff
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Re: Gotek With Sequential Prophet 2000

Post by Jeff »

Try the attached cfg file :shugart mode forced. Index mode enabled (DSKA0000.HFE,DSKA0001.HFE,DSKA0002.HFE,...)
Attachments
HXCSDFE.zip
(220 Bytes) Downloaded 445 times

apprenticemart2
Posts: 9
Joined: Tue Feb 21, 2012 3:26 pm

Re: Gotek With Sequential Prophet 2000

Post by apprenticemart2 »

Hi Jeff,

I can open that config file in the hxc software and see what the settings are?

If that's so then I have tried all the settings apart from the 2 drives emulation but I will try again with your config file.

At the moment I have the gotek installed in a Prophet 3000 instead and it seems to work fine in there as long as I don't use the format command by mistake.
If I use the format command with the Prophet 3000 it gives a scsi error and trashes the dska.hfe image, so similar problems to the Prophet 2000.
I also get some motor speed errors but that's probably buggy software and nothing to do with the gotek or the hxc firmware.
It is more than usable in the Prophet 3000. I will try some more testing with the Prophet 2000 at a later date and post back here.

Thanks for your help.
Martin

apprenticemart2
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Re: Gotek With Sequential Prophet 2000

Post by apprenticemart2 »

I have tried the config file and it makes no difference. The Prophet 2000 does not detect the Gotek or initialise its own ram correctly on the first power-up. I have to power-cycle again and then the Gotek is detected.

There is something that the Gotek does differently to the original Prophet 2000 disk drive on power-up (Original P2K drive sends some kind of data to the WD1770 even when no disk is inserted) and yet people with hxc floppy emulators don't have this problem? Strange.

Thanks for your help Jeff.

Martin

Jeff
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Re: Gotek With Sequential Prophet 2000

Post by Jeff »

To understand : is this a random issue ?
Can you make video to show me it ?

apprenticemart2
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Re: Gotek With Sequential Prophet 2000

Post by apprenticemart2 »

No this happens every time when the Prophet 2000 is on its first power up.

Let's say I switch on the Prophet 2000 for the first time today with the Gotek drive installed. It will not detect the Gotek and it does not initialise its own internal memory properly. If there is no disk then it should automatically load up preset sounds from EPROM and I should be able to hear these when I play on the keys. If I power up for the first time with a usb stick in the Gotek it will load up the disk image but again no sounds can be heard when I play a key.

I wait about 5 -10 seconds and then switch off the Prophet 2000 and then switch it on again. This time the Prophet 2000 will either load up a disk from the Gotek (if the usb stick is installed) or its own internal presets from EPROM if there is no usb stick installed. This is how it should work the first time I switch it on.

My guess is that maybe a capacitor or config data of the Gotek maintains charge/information during this short power cycle situation.

I can duplicate the effect by powering up the Prophet 2000 without a disk drive or Gotek installed and I get the same problem so it's like the Prophet 2000 does not detect the Gotek and the prophet 2000 does not like to not have a disk drive installed are the same problem.

Remember this happens on the first power up. If I want to duplicate this problem so that it happens all the time and every time then I have to wait 1 or 2 minutes between power ups. Then it will fail to detect the Gotek every time. Only a quick power cycle (switch on/wait for Prophet 2000 to boot/ switch off/ switch on) works.

If there are users with the proper hxc emulator hardware who are not having any problems then maybe the Gotek is just too slow to initialise and load the config file, but I couldn't see any major differences with an oscilloscope.

There is nothing visual going on that I could record with video.

I switch it on, it doesn't work. I switch it off and then quickly on again, now it works. This is repeatable. Not random.

I have put the original floppy drive back now as I have work to do. Thanks for your help Jeff.

I might try again later
Martin

mondo1976
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Re: Gotek With Sequential Prophet 2000

Post by mondo1976 »

Not that I'm a tech expert, but I think you're correct that it's a capacitor issue. I think the Prophet 2000 isn't supplying 5v to the Gotek quickly enough for it to initialize before the Prophet checks for the presence of a floppy.

Maybe replacing the PSU caps on the Prophet will eliminate the problem.

Jeff
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Re: Gotek With Sequential Prophet 2000

Post by Jeff »

mondo1976 wrote:Not that I'm a tech expert, but I think you're correct that it's a capacitor issue. I think the Prophet 2000 isn't supplying 5v to the Gotek quickly enough for it to initialize before the Prophet checks for the presence of a floppy.

Maybe replacing the PSU caps on the Prophet will eliminate the problem.
Yes this sound to be the problem.
Another possible issue -> The old drive used the +12V line. The gotek doesn't anymore so the 12V output of the power supply is not loaded anymore and this make the whole PSU unstable.

apprenticemart2
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Re: Gotek With Sequential Prophet 2000

Post by apprenticemart2 »

I will check the schematics about the 12v usage but I'm sure I already did, I think there are other uses for the 12v inside the Prophet 2000 not just the floppy but I will check. It is possible that the lower current draw means that the 12v supply is a little slower to stabilise now or it may not be needed any more and maybe this affects the wd1770 somehow. This could also be affecting the 5v as well.

As for the PSU. My Prophet has been totally rebuilt with new PSU caps and all of the decoupling capacitors have been replaced in the digital and analogue sections. As I mentioned in an earlier post the timing of the Gotek is a little slower than the floppy so maybe it is getting 5v slower than it needs but I have tried the Gotek from an external power supply so that it is powered up well before I give power to the Prophet and that didn't solve anything. Another thing I considered was the Prophet 2000 has a very long floppy cable as the drive is quite far away from the connector. I did try a shorter cable but that didn't make any difference.

Thanks for your help guys. I bet the problem is something really simple. I will double check my hfe files and try dumping an original disk again and also try some img files etc

Martin

apprenticemart2
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Re: Gotek With Sequential Prophet 2000

Post by apprenticemart2 »

OK Guys. It does seem to be power supply related. I'm not sure how it works exactly but I will try to explain it.

I left the original floppy drive connected to the power supply but disconnected the floppy drive cable and the Prophet made sounds from the first power-up (it loads presets from ROM when no floppy is inserted) If I power up the Prophet with the floppy drive cable unconnected and the power cable unconnected it does not make sounds on the first power-up.

I then made a cable so I could power the Gotek as well as the original floppy drive and plugged the Gotek into the floppy cable.
This time the Gotek powered up and loaded a disk image, and sounds were heard on the first power-up. NO power-cycle required.

The P2K has two +5v power supplies. One of these supplies does all the digital stuff apart from the memory expansion board and the floppy drive. The floppy drive and memory expansion socket has their own dedicated 5v supply. If this supply doesn't come up quick enough the Prophet won't detect a drive or the memory expansion and so it can't initialise itself and I have an expanded Prophet.

I think that's how it works. Now I have to find a way to simulate the extra current drawn by the floppy in order to help this 5v supply stabilise more quickly. I'm not sure if using a 78M05 or similar instead would do this (78M05 is probably the same as a 7805 internally) and I am also not sure yet if the 12v supply also has an effect on this. I will have to use something to put more load on the 5v and see if I can remove the original floppy. This should tell me if the 12v has an effect too.

Cheers
Martin

apprenticemart2
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Re: Gotek With Sequential Prophet 2000

Post by apprenticemart2 »

Ok. I have this working now. The problem was with the 12v supply. It was not working on the first power-up without the floppy drive installed but would start working after a quick power-cycle.

I replaced the 7812 regulator with a 78M12 and now it works fine.

This is strange to me because when the floppy drive is removed there is more than enough circuitry left over to give the 12v regulator some work to do. Maybe it was a quirk of this particular regulator. Hopefully no one else has to go to all this trouble to put a Gotek in their Prophet 2000.

Thanks for your help.
Martin

mondo1976
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Re: Gotek With Sequential Prophet 2000

Post by mondo1976 »

Thanks for the in-depth analysis. Much better than when people say, "got it working now" and never explain what the fix was.

Jeff
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Re: Gotek With Sequential Prophet 2000

Post by Jeff »

Thanks for the feedback.
Yes these regulators can oscillate if not correctly decoupled.

berenie
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Re: Gotek With Sequential Prophet 2000

Post by berenie »

Hello Jeff and others,

My gotek running hxc is much slower then the original floppy drive with both saving and loading. Is this normal behaviour?
Or am i missing something? jumper is at SO

Thanks :)

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