Write protect on floppy ?!

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exxos
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Write protect on floppy ?!

Post by exxos » Thu May 10, 2018 8:02 pm

When I try and write to the floppy, TOS says its write protected, but its not..

I've checked pin 25 of the WS1772, and it is high all the time as expected.. but what else can cause TOS to behave like that ?! I am using a STE, TOS206..

I had a guy having similar issues a few months ago, I am not sure if he ever solved it, I know he was changing all sorts of IC's and not sure he ever found the cause. I think he was using a STFM.

EDIT1:

The RDY pin on the DMA (pin 38) seems to have something to do with it all. With the scope probe on it, it behaves a lot better. Though not sure why yet...

Oddly it can format a floppy, but at the end , then says the floppy is write protected.. assume when its writes FAT.. When trying to partition a hard drive, it seems to "forget" the partition was created.. but it can format and sector test fine... so maybe some clue there in that both floppy and hard drive fail to create FAT tables for some reason ?
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

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kodak80
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Re: Write protect on floppy ?!

Post by kodak80 » Thu May 10, 2018 9:34 pm

Would it be worth trying a HC processor to see if it behaves differently?
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Re: Write protect on floppy ?!

Post by exxos » Thu May 10, 2018 9:37 pm

kodak80 wrote:
Thu May 10, 2018 9:34 pm
Would it be worth trying a HC processor to see if it behaves differently?
It has one :) But behaves the same with the original..
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

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Re: Write protect on floppy ?!

Post by exxos » Thu May 10, 2018 9:44 pm

So after much investigation.. It seems a 45R resistor in series with RDY pin seems to solve the problems..

This is the R303 side...
r452.png
r452.png (3.56 KiB) Viewed 391 times

and after the 45R (on DMA pin 38)
r45.png
r45.png (3.54 KiB) Viewed 391 times
Now the only difference seems to be less undershoot (but this is random anyway), BUT, like other problems I've seen with ground bounce type issues, the DMA side does seem to be more stable on the ground level.. On the resistor itself the ground seems to bounce, but it is only slight (see first image).

What people will like about this, as the problem seems to be a lot greater with the -38 DMA, but on the 001 DMA the problem does not seem to happen anywhere near as much. So again, I think the 001 DMA is just simply more noise immune than the -38.

Will experiment some more with the values.. This seems to be the cure so far.. The floppy and hard drive all seem to be behaving perfectly at the moment..

EDIT:

100R in series..
453.png
453.png (3.56 KiB) Viewed 390 times
The only thing is to be reducing is the undershoot voltage.. Still seems stable..

Though I have had this issue with 3 STE's so far, so this could likely be one of those problems which may start appearing for no reason...


Test setup.. not very exciting..

IMG_2628.JPG
IMG_2628.JPG (67.82 KiB) Viewed 388 times
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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Petari
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Re: Write protect on floppy ?!

Post by Petari » Fri May 11, 2018 8:12 am

Never heard about this problem. I think that main reason is aging of machines. For me, another argument to get rid of floppies.
This reminded me that Simbo was who talked about it at AF some 3 years ago. But I don't know, was he thinking about how to solve some things without floppy drive - like installing Hddriver ? Or maybe to play some game, what has no hard disk adaptation ?
Anyway, this reminded me that I need to add write protection flag, or 'better' said virtual CP tab to Virtual Floppy images :idea:
There is 2 kind of people: one thinking about moving to Mars after here becomes too bad, the others thinking about how to keep this planet habitable.

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Re: Write protect on floppy ?!

Post by exxos » Sun May 13, 2018 10:58 am

I've moved the rest of the posts to a new topic as its drifted onto its own subject now. . viewtopic.php?f=29&t=823
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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tzok
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Re: Write protect on floppy ?!

Post by tzok » Fri Jul 13, 2018 12:21 pm

I had similar issue, but I wasn't probing anything, just cleaned the WP switch on the floppy - it helped. I no longer use the floppy, but decided to keep it in its original place.

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