How to get TOS to see the 1.44MB drives

Update your old 720k to a 1.44 drive etc.
guus.assmann
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Re: How to get TOS to see the 1.44MB drives

Post by guus.assmann » Tue Oct 24, 2017 5:26 pm

Hello,
Finally I found the problem.
The drive electronics don't switch to 1,44 function reliably.
The switch that detects the disk works fine, however the drive doesn't always work in 1,44 mode.
In 720K is works fine all the time.

I found out by using another drive, a TEAC FD235 FD.

BR/
Guus Assmann

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Re: How to get TOS to see the 1.44MB drives

Post by exxos » Tue Oct 24, 2017 5:48 pm

Maybe the density select switch is faulty ?
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guus.assmann
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Re: How to get TOS to see the 1.44MB drives

Post by guus.assmann » Mon Nov 06, 2017 2:16 pm

Hello Exxos,
As far as I can see, the switch is ok.
I've been looking for the data-sheet of the controller on the drive, but I only get sites where they want to sell the IC's.

One more thing.
In my STE, there's an 8 Mhz oscillator.
It would be nice if I could exchange this for a 16Mhz one.
The GAL should then make the 8Mhz that's needed for 720K operation.
This saves the wire to a 16Mhz signal and needs a small modification of the module.
Just leave out one resistor and make a wire from the clock pin on the socket to the 16Mhz input for the GAL.
Is this feasable?

BR/
Guus

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Re: How to get TOS to see the 1.44MB drives

Post by exxos » Mon Nov 06, 2017 2:33 pm

Not really sure you are trying to do their to be honest...

The mega buffer board I think as 2x 16mhz outputs, you use one output for the booster, and all the output the floppy board. That is all you really need to do.

I would really check with the scope on the clock pin of the 1772, try and access a 720K floppy and you should see 8 MHz on the pin.

Then try accessing a 1.44 floppy, and you should see the clock signal jump to 16mhz. If you do not see this change, then something is wired wrong somewhere.

The only wire you need here, is a high-density select wire from the floppy drive to the module. This feeds it the signal to tell the floppy controller if to use 8 MHz or 16 MHz.

I would also suggest using the recommended floppy drive as well which is the MPF920, and make sure you are working with the recommended setup, before changing around things, as any small change you make could be the cause of the malfunction.

EDIT:
I see earlier you said the module was switching between 8 and 16mhz, this makes me wonder if it is actually your floppy drive some reason is malfunctioning in 1.44 mode.

I had a look around and I believe the 380 is not capable of 1.44 modes...
4MB STFM 1.44 FD- VELOCE+ 020 STE - 4MB STE 32MHz - STFM 16MHz - STM - MEGA ST - Falcon 030 CT60 - Atari 2600 - Atari 7800 - Gigafile - SD Floppy Emulator - PeST - HxC - CosmosEx - Ultrasatan - various clutter

https://www.exxoshost.co.uk/atari/ All my hardware guides - mods - games - STOS
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guus.assmann
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Re: How to get TOS to see the 1.44MB drives

Post by guus.assmann » Mon Nov 06, 2017 3:18 pm

Hello Exxos,
Sorry, I've made it a bit confusing. There's 2 seperate things going on right now.
1) I changed the board and want to install in a STE. Then I saw the 8Mhz oscillator and wanted to change that for 16Mhz.
If the GAL would make 8Mhz out of this, it would be easier to install.
And there's no Shifter board in that computer.

2) The Mega ST has a Shifter buffer board.
And the 8 / 16 switching works just fine, I've checked with the scope.
Using an FD235, all works just fine. (Just the FD235 is a bit old, hence noisy)
But the 380 has a problem. It does have a switch for detecting 1,44 and this is connected to the controller IC.
That's why I was looking for the data sheet. My thoughts: why would a drive have the switch and a connection, but no 1,44 support.
Furthermore, I have 3 pieces 380 drive and only 1 FD235.
But eventually I have more than 1 computer that I would like to install a 1,44 drive unit into.

BR/
Guus

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Re: How to get TOS to see the 1.44MB drives

Post by troed » Mon Nov 06, 2017 3:33 pm

guus.assmann wrote:
Mon Nov 06, 2017 3:18 pm
But the 380 has a problem. It does have a switch for detecting 1,44 and this is connected to the controller IC.
That's why I was looking for the data sheet. My thoughts: why would a drive have the switch and a connection, but no 1,44 support.
Furthermore, I have 3 pieces 380 drive and only 1 FD235.
But eventually I have more than 1 computer that I would like to install a 1,44 drive unit into.
Epson 380? Those are DD.

Some 300 are HD, most are DD.

Epson 340 is HD.

There's physical space and pads on the 380 board for a switch, but I don't think I've seen it populated.

/Troed

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Re: How to get TOS to see the 1.44MB drives

Post by exxos » Mon Nov 06, 2017 3:55 pm

guus.assmann wrote:
Mon Nov 06, 2017 3:18 pm
1) I changed the board and want to install in a STE. Then I saw the 8Mhz oscillator and wanted to change that for 16Mhz.
If the GAL would make 8Mhz out of this, it would be easier to install.
The board does not get in the way of the osc ? So I don't know why you would want to do anything else to the install... It would just be making it overcomplicated..

Image

guus.assmann wrote:
Mon Nov 06, 2017 3:18 pm
Using an FD235, all works just fine. (Just the FD235 is a bit old, hence noisy)
But the 380 has a problem.
This explains it then, if one drive works on another does not, and that drive obviously as troed says is not 1.44 capable.
4MB STFM 1.44 FD- VELOCE+ 020 STE - 4MB STE 32MHz - STFM 16MHz - STM - MEGA ST - Falcon 030 CT60 - Atari 2600 - Atari 7800 - Gigafile - SD Floppy Emulator - PeST - HxC - CosmosEx - Ultrasatan - various clutter

https://www.exxoshost.co.uk/atari/ All my hardware guides - mods - games - STOS
https://www.exxoshost.co.uk/atari/last/storenew/ - All my hardware mods for sale - Please help support by making a purchase.

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Re: How to get TOS to see the 1.44MB drives

Post by guus.assmann » Mon Nov 06, 2017 8:12 pm

Hello Exxos,

Yes, the drive is a problem indeed.
Still, why does it have the switch for 1,44, when it's not capable of HD?
And I also have 1 drive that doesn't have the switch.
I'll investigate some more and will make a nice invertory.

About the installation in the STE:
Again, communication is difficult when writing is all we get as a tool.... I'll give it another go, maybe I can explain better. ;)
The 8Mhz oscillator on the MB is the normal input to the Floppy-controller.
The floppy controller has to be socketed anyway, so why not replace the Oscillator as well.
Of course a 16Mhz one, it will be spot on correct for the Floppy-controller in HD mode.
Then there's no need to get a wire connected to the 16,01xMhz on the STE.
And connecting that wire to 16Mhz is a tad complicated, as it's a tiny trace.
The 16Mhz can be divided by 2 in the GAL.
The Gal can then either connect 8Mhz to the FDC or 16Mhz it gets from the replaced oscillator.
And the traces from the clock, both from the socket and the FDC go to the GAL anyway. (It may just need to go to pin 1)
To me, this seems to be a tad less complicated and at least excludes a possible problem with the 16Mhz on the STE board.

BR/
Guus

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Re: How to get TOS to see the 1.44MB drives

Post by exxos » Mon Nov 06, 2017 8:50 pm

guus.assmann wrote:
Mon Nov 06, 2017 8:12 pm
Still, why does it have the switch for 1,44, when it's not capable of HD?
And I also have 1 drive that doesn't have the switch.
It could just be the production run of the PCB, they could have fitted the switch originally, then decided not to fitted on later PCB runs to save cost.

I have half a feeling I saw this many years ago where floppy drives seem to have a HD switch in there, even though they were still only 720K drives.

But is only a guess..
guus.assmann wrote:
Mon Nov 06, 2017 8:12 pm
About the installation in the STE:
Again, communication is difficult when writing is all we get as a tool.... I'll give it another go, maybe I can explain better. ;)
The 8Mhz oscillator on the MB is the normal input to the Floppy-controller.
The floppy controller has to be socketed anyway, so why not replace the Oscillator as well.
Of course a 16Mhz one, it will be spot on correct for the Floppy-controller in HD mode.
Then there's no need to get a wire connected to the 16,01xMhz on the STE.
And connecting that wire to 16Mhz is a tad complicated, as it's a tiny trace.
The 16Mhz can be divided by 2 in the GAL.
The Gal can then either connect 8Mhz to the FDC or 16Mhz it gets from the replaced oscillator.
And the traces from the clock, both from the socket and the FDC go to the GAL anyway. (It may just need to go to pin 1)
To me, this seems to be a tad less complicated and at least excludes a possible problem with the 16Mhz on the STE board.
Try it, let me know :)
4MB STFM 1.44 FD- VELOCE+ 020 STE - 4MB STE 32MHz - STFM 16MHz - STM - MEGA ST - Falcon 030 CT60 - Atari 2600 - Atari 7800 - Gigafile - SD Floppy Emulator - PeST - HxC - CosmosEx - Ultrasatan - various clutter

https://www.exxoshost.co.uk/atari/ All my hardware guides - mods - games - STOS
https://www.exxoshost.co.uk/atari/last/storenew/ - All my hardware mods for sale - Please help support by making a purchase.

guus.assmann
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Re: How to get TOS to see the 1.44MB drives

Post by guus.assmann » Tue Nov 07, 2017 8:22 am

Hello Exxos,

I have removed the 8Mhz oscillator and put a socket in the board.
But I think it will not work.
Is there a devider in the GAL, so it will produce the 8Mhz?

I've measured that pin 22 of the socket (CLK) goes into the GAL Pin 6.
And the FDC is connected to pin 14 of the GAL.
So does the GAL switch the signal from pin 6 to 14, or does it make 8Mhz by deviding the 16Mhz it gets?
In that case, input to pin 6 doesn't make much sense...

BR/
Guus

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