Gotek having A: and B: with same content

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mikro
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Gotek having A: and B: with same content

Post by mikro »

Yeah, me and Gotek again! :)

Today I've noticed a really strange thing -- I wanted to copy some files from one disk image to another (and was lazy to fire up Hatari). I expected that when I click on B:, I'll get the well known "Please insert a disk into the floppy and press enter" dialog but to my surprise, I saw content of A: there! Just to be sure I set two slots (1 & 2) with different images and nope, A: and B: still contained the content from slot 1.

Any idea how to change that? I'd be fine with A: only but of course if it's possible to simulate both of them (slot 1 = A:, slot 2 = B:), I'd be even happier.

I have S0 and MO jumpers set, it's possible it has something to do with that.
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Re: Gotek having A: and B: with same content

Post by kolli »

mikro wrote: Any idea how to change that? I'd be fine with A: only but of course if it's possible to simulate both of them (slot 1 = A:, slot 2 = B:), I'd be even happier.
With unmodified Gotek the disk change isn't correctly detected on the Atari because of their somewhat strange implementation in hardware. Look here: http://www.tonmann.com/2014/08/gotek-fl ... -atari-st/
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Re: Gotek having A: and B: with same content

Post by mikro »

OK but disk change is something else (I think). If I have one floppy drive, clicking on B: should ask me for inserting another disk into A:, not opening the same content in B:.
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Re: Gotek having A: and B: with same content

Post by ijor »

You have your jumpers wrong, or there is a problem with the gotek. Seems your gotek is using the motor signal instead of the select signal for being selected. And because the ST, unlike the PC, has just a single motor signal, all drives see motoron asserted whenever any drive is accessed.

So your Gotek is being selected when either drive is accessed. Also as a consequence of this, TOS believes you have two drives. Note that the Gotek firmware doesn't know that, it has no way to know.
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Re: Gotek having A: and B: with same content

Post by joska »

mikro wrote:Any idea how to change that? I'd be fine with A: only but of course if it's possible to simulate both of them (slot 1 = A:, slot 2 = B:), I'd be even happier.
Do you have Gotek or HxC firmware in your floppy emulator?
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Re: Gotek having A: and B: with same content

Post by mikro »

Joska: it's HxC firmware of course.

Ijor: so I'm not completely crazy! Guys today were trying to convince me this is how it was with normal floppy as well (we couldn't verify) but I couldn't believe that. Thank you for confirmation, I will dig more.

I'm not sure about the S0 / MO jumpers at all. I read it on one website because there wasn't any official tutorial how to set it for Atari.

P.S. Gotek is OK, we tried it on a couple of units, same behaviour (with the same jumpers).
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Re: Gotek having A: and B: with same content

Post by ijor »

joska wrote:
mikro wrote:Any idea how to change that? I'd be fine with A: only but of course if it's possible to simulate both of them (slot 1 = A:, slot 2 = B:), I'd be even happier.
Do you have Gotek or HxC firmware in your floppy emulator?
It doesn't matter, you can't simulate two drives in the ST without some hardware mod. The drive receives a single select signal, it has no way to know which drive is being accessed.

I believe there are some limitations on the Gotek hardware as well. I would need to check the schematics, but I think that the internal controller gets a single select signal anyway.

So it is not possible to simulate both drive in the ST, neither with the original HxC drive.

And, I think, the Gotek can't simulate two drives at all disregarding the system and the firmware.
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Re: Gotek having A: and B: with same content

Post by joska »

mikro wrote:Joska: it's HxC firmware of course.
I ask because the Falcon floppy connector is a Shugart connector, which differs a little bit from the common PC/AT floppy connector.

Shugart: Pin 10, 12 and 14 is drive select 0, 1 and 2. Pin 16 is motor on for the selected drive.
PC: Pin 10 and 16 is motor enable A and B, 12 and 14 is drive select B and A.

So when the Falcon selects drive A (drive 0), it actually enables motor B and A on the PC drive but does not pull down any of the drive select lines. I would assume that the HxC firmware actually implements the Atari floppy bus (it claims to support both Shugart and PC) here so this should not be a problem in that case. But it sounds like your Falcon thinks there's a drive B, most likely because the Gotek responds when TOS tries to detect drive B and pin 16 is pulled low and doesn't care about the drive select signals.

I'll have a look at the jumper settings on my Gotek tonight.
Last edited by joska on Fri Mar 10, 2017 1:05 pm, edited 1 time in total.
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Re: Gotek having A: and B: with same content

Post by joska »

ijor wrote:
joska wrote:Do you have Gotek or HxC firmware in your floppy emulator?
It doesn't matter, you can't simulate two drives in the ST without some hardware mod. The drive receives a single select signal, it has no way to know which drive is being accessed.
See my reply to mikro.
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Re: Gotek having A: and B: with same content

Post by mikro »

Yep, Ijor was right all along, removing "MO" jumper has fixed the issue.

It would be pretty cool to have one Gotek serving both A: and B: ... so it's not possible on Atari in any floppy emulator?
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Re: Gotek having A: and B: with same content

Post by ijor »

joska wrote:I would assume that the HxC firmware actually implements the Atari floppy bus (it claims to support both Shugart and PC) here so this should not be a problem in that case. But it sounds like your Falcon thinks there's a drive B, most likely because the Gotek responds when TOS tries to detect drive B and pin 16 is pulled low and doesn't care about the drive select signals.
It's not up to the firmware. It's about the board and the jumpers. The microcontroller at the Gotek gets a single select signal, and no motor signal at all. The jumpers determine which signal from the external connector goes to the controller.
mikro wrote:It would be pretty cool to have one Gotek serving both A: and B: ... so it's not possible on Atari in any floppy emulator?
The Gotek can't do it, no matter the firmware, no matter the platform.

The ST can't do it, no matter the floppy emulator, without some hardware mod. You would need to bring the other select signal to the internal floppy cable, or to the emulator connector (same thing). But again, not on the Gotek.
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Re: Gotek having A: and B: with same content

Post by joska »

mikro wrote:Yep, Ijor was right all along, removing "MO" jumper has fixed the issue.
Good. So this means that the HxC firmware attempts to autodetect Shugart/PC mode.
mikro wrote:It would be pretty cool to have one Gotek serving both A: and B: ... so it's not possible on Atari in any floppy emulator?
It is possible with the HxC floppy emulator, and possibly with the Gotek with HxC firmware. However, it needs both drive select signals to be present on the floppy bus, and I believe only the Stacy has that. But it's quite easy to modify any ST/STE, run wire 12 on the floppy connector to pin 19 (IOA2, drive B select) on the YM, I did that on both my Megas. Should be possible to do the same on the Falcon. But look up the YM pinout on the Falcon!
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Re: Gotek having A: and B: with same content

Post by ijor »

joska wrote:
mikro wrote:It would be pretty cool to have one Gotek serving both A: and B: ... so it's not possible on Atari in any floppy emulator?
It is possible with the HxC floppy emulator, and possibly with the Gotek with HxC firmware. However, it needs both drive select signals to be present on the floppy bus, ...
Again, that's not enough for the Gotek, no matter the firmware. See Gotek's schematics.
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Re: Gotek having A: and B: with same content

Post by joska »

ijor wrote:Are we talking about a Falcon?
Yes, I believe mikro is using a Falcon.
ijor wrote:It's not up to the firmware. It's about the board and the jumpers. The microcontroller at the Gotek gets a single select signal, and no motor signal at all. The jumpers determine which signal from the external connector goes to the controller.
I see. So select whether to use the motor on signals or drive select signals to assert the drive. And if you use both, the Falcon will assert both drives since it always pulls down the PC "motor B" when accessing any floppies.

In that case it's not possible to use the Gotek as both A and B simultaneously without some sort of modification.
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Re: Gotek having A: and B: with same content

Post by ijor »

joska wrote:In that case it's not possible to use the Gotek as both A and B simultaneously without some sort of modification.
Correct. And even then you'll need a custom firmware because, as a consequence of the hardware limitation, the firmware doesn't support multiple drives.
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Re: Gotek having A: and B: with same content

Post by joska »

ijor wrote:Again, that's not enough for the Gotek, no matter the firmware. See Gotek's schematics.
There is no reason why the firmware can't use another input for the drive 2 select. However, while it *can* do that, it doesn't so with the current firmware it's clearly not possible to emulate two drives at once.
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Re: Gotek having A: and B: with same content

Post by ijor »

joska wrote:There is no reason why the firmware can't use another input for the drive 2 select ...
Sorry, I edited my message while you was replying. But yes, we agree.
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Re: Gotek having A: and B: with same content

Post by mikro »

Actually I wasn't specific about the computer but in fact you're both right, I was looking for both ST and Falcon answer because the original problem was present on both. ;)

Thank you both for interesting information -- so you're saying that HxC Emulator (with DS1 routed from the YM if needed) should be able to emulate both A: and B: but for Gotek even this is not enough?
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Re: Gotek having A: and B: with same content

Post by joska »

The JA jumper is used for a Select button, but are the JB and JC jumpers used for anything? Hardware-wise it could be as simple as setting a jumper across S0 and JB, and a jumper on S1. Then JB would be the drive A select line, and S1 the drive B select line.
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Re: Gotek having A: and B: with same content

Post by joska »

mikro wrote:Thank you both for interesting information -- so you're saying that HxC Emulator (with DS1 routed from the YM if needed) should be able to emulate both A: and B: but for Gotek even this is not enough?
I don't have an HxC but the HxC documentation say that it can emulate both drives at once:
> Two floppy disk drives emulation. (Two floppy disk drive emulator in One !)
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Re: Gotek having A: and B: with same content

Post by ijor »

mikro wrote:Thank you both for interesting information -- so you're saying that HxC Emulator (with DS1 routed from the YM if needed) should be able to emulate both A: and B: ...
It should, but not sure if it was tested on the ST.
joska wrote:The JA jumper is used for a Select button, but are the JB and JC jumpers used for anything? Hardware-wise it could be as simple as setting a jumper across S0 and JB, and a jumper on S1. Then JB would be the drive A select line, and S1 the drive B select line.
If the available schematics are correct, the three JA, JB & JC jumpers are grounded.

Btw, I now realize the cheap design of the Gotek. The jumpers actually jumper the signals. That means that if you jumper both M0 & S0 (as many do), then your are connecting (and then shortcutting) the ST signals directly!
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Re: Gotek having A: and B: with same content

Post by joska »

ijor wrote:If the available schematics are correct, the three JA, JB & JC jumpers are grounded.
They are not grounded if the jumpers are removed.

Image
ijor wrote:Btw, I now realize the cheap design of the Gotek. The jumpers actually jumper the signals. That means that if you jumper both M0 & S0 (as many do), then your are connecting (and then shortcutting) the ST signals directly!
Yes, now that I'm actually looking at the schematics it's obvious that you are not supposed to set more than one of these jumpers.
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Re: Gotek having A: and B: with same content

Post by joska »

mikro wrote:Thank you both for interesting information -- so you're saying that HxC Emulator (with DS1 routed from the YM if needed) should be able to emulate both A: and B:
Something just occured to me - with the HxC you probably don't have to modify the ST/Falcon to do this. Motor on will be asserted regardless of drive, so if motor on is asserted but d0 isn't, then assume that d1 is being accessed.

I have no idea if HxC does it like this but I believe this should work just fine.
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Re: Gotek having A: and B: with same content

Post by ijor »

joska wrote:Something just occured to me - with the HxC you probably don't have to modify the ST/Falcon to do this. Motor on will be asserted regardless of drive, so if motor on is asserted but d0 isn't, then assume that d1 is being accessed.

I have no idea if HxC does it like this but I believe this should work just fine.
That's not a bad idea, but it has some problems and it should be tested.

Sometimes the ST enables the motor but doesn't select any drive. Activating the drive just by motor being on might bring some incompatibilities. And although not very common, there were some adapters that supported 4 floppy drives, But yeah, it would be extremely unusual to use one of those and a floppy emulator at the same time. There are also situations that the ST selects the drive without turning on the motor, such as when checking for media change. So media change won't work.

I can't say I'm 100% sure, but I don't think the HxC firmware implements that behavior.
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