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Strangest phenominon ever on my c64 1541 diskdrive


johannesmutlu

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17 hours ago, OLD CS1 said:

No.  A 1541/C/II is a single-sided floppy drive.  Reading side "B" requires physically flipping the disk.  The drive does not know the difference between the sides.

Same head is used reading the flip-side as the front-side.  Ostensibly the same for the writing drive.

This is an interesting thought.  The problem between the 1541-C and the 1541-II might be that the drive does not detect when the disk is flipped, thus the 1541-C might be trying to use the old directory cached in memory.  Someone else is going to have to chime in on that -- this is just hypothesis.  A way to test that would be to power up the system, put in the flip-side of the disk, and immediately ask for a directory.  If that works, then try loading one of the programs.

This only makes sense if the disk is misshapen, or there is a tab (like one of those fancy write-protect tabs he has put on the disk) which is snagging something inside the drive.

See my thoughts above on the disk change detection.  IIRC, DOS detects a disk change by the toggling of the write protect sensor.  With the tabs in place, that toggling could be defeated, though I expect that a full disk removal and insertion should have the same effect.

 

Anyway, the problems you are having make little sense to me without this fantasy.

This is also interesting.  So in this experiment, you could read the directory ($) from side "B" but not side "A".  Leads me again to consider the disk change detection, but it gets into the weeds a little.  Unfortunately, I do not have a 1541-C to test.

Well that’s what i want to try to tell you,side A does get readed but if i try to flip the disk on side B,it hardly get’s inside the diskdrive and if i get it inside,it doesn’t read anything,it doesn’t load the rom,and it doesn’t show the directory ,

i tried it with and with those stickers on the side,,

now the only difference between side A & B is that side B seens to be slightly deeper down because of those folded plastic on the side but that shouldn’t made any sense right? since side B is only i milimeter or less deeper then side A so i can’t see why that could have a negative impac on the reading head,also i can’t see why i case the reading is is dirty,it only could read side A ,either way it’s as  bizar as it can get.

354333D4-02CC-4383-BBB4-842AE3F5044A.jpeg

3627BD6B-F82A-4515-9258-A35EB05B303A.jpeg

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5 hours ago, johannesmutlu said:

the only difference between side A & B is that side B seens to be slightly deeper down because of those folded plastic on the side but that shouldn’t made any sense right?

No, the folds should not make a difference.  There is normally plenty of clearance inside the drive.

5 hours ago, johannesmutlu said:

i can’t see why that could have a negative impac on the reading head,also i can’t see why i case the reading is is dirty,it only could read side A ,either way it’s as  bizar as it can get.

Right.  It is possible that the drive itself has some kind of damage or something stuck inside the loading slot which is impacting the disk, but I expect that would impact irrespective of the side you insert.  This is very bizarre, indeed.

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I still think there's some write protect tab or partial label stuck inside the drive.  For what ever strange combination of elements, it doesn't impede the use of side A, but does affect the use of side B.  If you removed all of those labels and write protect tabs stuck all over the diskette, I'm going to guess that your loading problems go away.  Or, take off the drive cover and look inside to see if there is any foreign object inside.  If there's a chance there is something inside, it's only a matter of time before it gets somewhere that causes even more problems.

Edited by Virtualsky
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Hi guys i may have found the problem but i am not sure but i may get the ansure,the seller may have indeed burned side A and side B on a 1541 || diskdrive without flipping the disk,as a result side B cannot be readed on a 1541C diskdrive because side B was written in reverse by the reading head of that 1541 || diskdrive,

the 8but guy on youtube told that, if my theory is right then i have found the mistake he made,in such case he should,ve stated that side B can be only readed by the 1541 || diskdrive,

if he wanted to make his multi rom diskettte compatible with both diskdrive 1541C and 1541 ||, then all he had to do instead was just flip the diskette and burn side A and B that way instead rather then leave it inside the 1541 || and burn side B in reverse by the 2nd reading head,

in such case i wish i discovered it much much earlier sothat i could,ve beg him for a burned disk with the 1541C in mind,

eventrough he claims that both reading heads from the 1541 || only do read the disk from one side,but i don’t believe that as the 8bit guy proved otherwise,

in such case it’s pointless to beg him for another one since she probably wouldn’t decide to burn the disk the other way by flipping it on her diskdrive 1541 || 

anyway i can only speculate,but i don’t see why on earth side A can be readed but not side B because of potentially damaged chips caused by heat on my 1541C according to her statements about it,would be laving and strange if that’s true,mmmm

becides i will hardly believe her is she claims that she did tested both side A and B from that multi rom disk successfully on the 1541C diskdrive.

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Not reading from the flip-side of a flippy does not make sense to me.  The 1541 does not require an index pulse, it uses sync marks.  If the disk was "burned" 🙄 using a 1571 and the writer just wrote the disk image by selecting the second side of the disk without actually flipping it, then, yes, I can see the 1541 could not read the flipped side.

 

Something just does not add up, here.  I would be willing to try the disk, myself, if I could get my hands on it.  Something here ain't mathin'.

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15 hours ago, OLD CS1 said:

I wonder if Super Mario Bros. is the actual homebrew release, or the re-skin of The Great Giana Sisters from bitd.

Well it is the actual homebrew version of supermariobros,

in case you want that multi rom disk,heres the link to it,

you try contact the seller as well.

 

https://www.ebay.nl/itm/354331312001?mkcid=16&mkevt=1&mkrid=1346-175129-2357-0&ssspo=hp2fawwxrxa&sssrc=4429486&ssuid=x5mjHw5WR9a&var=&widget_ver=artemis&media=COPY

Edited by johannesmutlu
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20 hours ago, OLD CS1 said:

Not reading from the flip-side of a flippy does not make sense to me.  The 1541 does not require an index pulse, it uses sync marks.  If the disk was "burned" 🙄 using a 1571 and the writer just wrote the disk image by selecting the second side of the disk without actually flipping it, then, yes, I can see the 1541 could not read the flipped side.

 

Something just does not add up, here.  I would be willing to try the disk, myself, if I could get my hands on it.  Something here ain't mathin'.

20 hours ago, OLD CS1 said:

Not reading from the flip-side of a flippy does not make sense to me.  The 1541 does not require an index pulse, it uses sync marks.  If the disk was "burned" 🙄 using a 1571 and the writer just wrote the disk image by selecting the second side of the disk without actually flipping it, then, yes, I can see the 1541 could not read the flipped side.

 

Something just does not add up, here.  I would be willing to try the disk, myself, if I could get my hands on it.  Something here ain't mathin'.

Well i would be not surprised if the seller used here 1541 || to write both side A & B without flipping the disk,in such case my 1541C could only read sise A because on side B all data are written in reverse order by the second reading wich writes the  data in the opposed order (whether inside out or ouside in),as a result only the 1541 || could read side B and not the 1541C,HOWEVER if the seller just flipped the disk from side A to side B then side B will be just written in the exact order by the first reading head sothat also side B can be readed by the 1541 diskdrive,

If my theory is right i wouldn’t be surprised about this according to the 8bit guy ,

heres the link to it so you and others can judge for their selfes🤣

 

 

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4 hours ago, johannesmutlu said:

Well it is the actual homebrew version of supermariobros,

in case you want that multi rom disk,heres the link to it,

you try contact the seller as well.

 

https://www.ebay.nl/itm/354331312001?mkcid=16&mkevt=1&mkrid=1346-175129-2357-0&ssspo=hp2fawwxrxa&sssrc=4429486&ssuid=x5mjHw5WR9a&var=&widget_ver=artemis&media=COPY

I am actually irritated about this disk, if it indeed comes with Fix It Felix, Jr.  That game is a name-your-price itch.io release, and the author likely receives none of these disk sales.  Everything else on the disk can be found easily on-line.

 

Honestly, I would rather make you a disk of these games, test it, and send it to you than have this fuckwad make another dollar/euro on it.

 

https://brokenbytes.itch.io/fix-it-felix-jr

 

 

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1 hour ago, OLD CS1 said:

Sorry, I am not watching a 30-minute video for one piece of information I need.  Summarize it in one word.

 

 

Ahahahaha,you don’t have to watch the enrire 30 minute video,you only need to watch from 10:30 till 12:10 to get the ansure/massage wich i want/mean to tell you including everybody elso,

my apologize as it turns out he talks about the 1571 diskdrive,but still trough according to the seller that 1541 || does have two reading heads as well.

but still trough i really wonder what your touts (including everybody else’s touts) are about the 1571 diskdrive once watched that small part of the video,

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On 9/22/2023 at 4:44 AM, johannesmutlu said:

potentially damaged chips caused by heat on my 1541C according to her statements about it,would be laving and strange if that’s true,mmmm

I just noticed this.  No.  Not reading a flip-side of a disk when the front side works fine is not caused by damaged chips in the drive.  She is full of "chips."  She has made me rather angry -- first, she includes what amounts to a commercial release on her disks, and second the statements she makes about your drive are quite dubious.

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7 hours ago, OLD CS1 said:

Turns out I do have a 1541-C in my inventory.  I just conducted an experiment in which I used my 1541-II to format two sides of the same floppy disk. Then, I took that disk to the 1541-C and performed a directory on both sides, successfully.

 

C1541-CReadingFlippyDisk.thumb.JPG.f95a2c051ea30f778c7b369dea7667b3.JPG

Well uh in case you also own a 1571, now try do the same thing,format the floppy disk on both sides without flipping the disk,then write a rom to it on both sides again without flipping the disk,and then try it on the 1541C and see if it can not only read side side A but also side B,if it turns out that it can only read side A then i think i have found the ansure to the problem of my 1571 C diskdrive at why it only reads side A and not side B.with the theory that according to the 8bit guy that ‘the second reading head of the 1571 writes the data on the opposide direction as opposed to side A sothat only side A can be readed on both the 1541 C but side B only on the 1571’

so can you or somebody else try this out in case you do own a 1571???

if you do,then thanks alot,or let somebody else try this out with his 1571 diskdrive,

then post the results to give us the ansure.

either way whoever will do it,thanks alot😁🤣

 

Edited by johannesmutlu
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7 hours ago, OLD CS1 said:

In case there is any question about this statement.

 

C1541-IIDriveHeadandPressurePad.thumb.JPG.f1b8b9030e31940d12f7ad4c9f284148.JPG

Well if the 1541 C and even the 1541 || diskdrive has only 1 reading head on the. Bothem for side A,then i suppose that the 1571 diskdrive with it’s double sided reading head does use the top reading head for side B to read and write data in the opposite way as of the bothem reading head for side A ,thus rendering side B became incompatible on bothe the 1541 C and 1541 || in accordence to the 8bit guy,mmmm.

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@johannesmutlu All of your statements are correct.  In the simplest terms and the most convenient definitions: no 1541 drive or clone of any model will read the second side of a disk formatted in a 1571 drive by which the disk was not written in single-sided mode and was not physically turned over.


Redundant details here:

Spoiler

The 1541 series of disk drives only have one read head.  To utilize the second side of a disk, you physically turn the disk over.  That is what I did in this experiment.  We colloquially call these disks "flippies" or a "flippy disk" because of the physical action required.

 

There is no need to conduct an experiment with a 1571 as the results are well-known.  The 1571 has heads on both the top and bottom.  There are two ways the 1571 can utilize the second side of the disk.  The first is a full double-sided format, which produces a disk with 1328 blocks contiguously accessed across both sides of the disk without flipping it over.  This is how all double-sided drives work.

 

The second way a 1571 can access the second side of a disk is to run it in 1541 mode using the U0>M1 command (also the default mode when connected to a Commodore 64,) then issue the command U0>H1 which tells the drive to use head number 1 (the top head.)

 

The issue with both of these methods is the direction of rotation.  Using the top head to access the second side of the floppy disk without physically flipping the disk, from the perspective of the 1541 which would use the bottom head to read the disk, the data is written in the opposite direction of rotation.

 

IF the second method described was used to create the disk -- that is, writing a 1541 image in regular mode, then issuing the U0>H1 command and writing the second 1541 image -- then the second side of the disk will be unreadable in any1541 drive because that side rotates in the wrong direction.

 

As you conclude, the only way to test the hypothesis is to try the disk you purchased in a 1571 drive.  I assume you do not know anyone near you who can assist with such a test.

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I also don't understand why anyone would do this with a 1571.  It would take a series of commands that very few people would ever have the use of to create a wrong-way flippy disk...  

 

While it certainly is possible to format a double sided disk as 2 single sided disks in a 1571, there's no practical reason to do that.  Formatting them single sided by turning over the disk to format the second side would make them compatible with a 1541.  Formatting them as 2 single sided disks in the 1571 would not do anything more than give you the same size as a double-sided format, but with the added inconvenience of having to send disk head change commands to see the back side.

 

Clearly whoever put this disk together doesn't know what they are doing.

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1 hour ago, Casey said:

I also don't understand why anyone would do this with a 1571.  It would take a series of commands that very few people would ever have the use of to create a wrong-way flippy disk... 

Exactly this.  Even using CBMXfer it takes a good bit of effort.

 

One could use the CBM tools to script the process, but why do it this way?  Anyone with a modicum of Commodore knowledge would know this is not The Way.  The only reasonable notion would be that flipping the disks takes extra time, but then it looks like they are notching the disks and covering the notch.  The whole thing seems completely unreasonable, but then the evidence, assuming absolutely nothing esoteric is wrong with his drive, points to this conclusion.

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1 hour ago, OLD CS1 said:

@johannesmutlu All of your statements are correct.  In the simplest terms and the most convenient definitions: no 1541 drive or clone of any model will read the second side of a disk formatted in a 1571 drive by which the disk was not written in single-sided mode and was not physically turned over.


Redundant details here:

  Reveal hidden contents

The 1541 series of disk drives only have one read head.  To utilize the second side of a disk, you physically turn the disk over.  That is what I did in this experiment.  We colloquially call these disks "flippies" or a "flippy disk" because of the physical action required.

 

There is no need to conduct an experiment with a 1571 as the results are well-known.  The 1571 has heads on both the top and bottom.  There are two ways the 1571 can utilize the second side of the disk.  The first is a full double-sided format, which produces a disk with 1328 blocks contiguously accessed across both sides of the disk without flipping it over.  This is how all double-sided drives work.

 

The second way a 1571 can access the second side of a disk is to run it in 1541 mode using the U0>M1 command (also the default mode when connected to a Commodore 64,) then issue the command U0>H1 which tells the drive to use head number 1 (the top head.)

 

The issue with both of these methods is the direction of rotation.  Using the top head to access the second side of the floppy disk without physically flipping the disk, from the perspective of the 1541 which would use the bottom head to read the disk, the data is written in the opposite direction of rotation.

 

IF the second method described was used to create the disk -- that is, writing a 1541 image in regular mode, then issuing the U0>H1 command and writing the second 1541 image -- then the second side of the disk will be unreadable in any1541 drive because that side rotates in the wrong direction.

 

As you conclude, the only way to test the hypothesis is to try the disk you purchased in a 1571 drive.  I assume you do not know anyone near you who can assist with such a test.

Well i indeed don’t know anybody in my neightborhood who owns a 1571 diskdrive,but my local gameshop down the city may do have one sothat i can buy it for testing it,but if they don’t have (wich i assume) then i probably need to fork over a whopping $385 dollars + €58 shipping costs on ebay ,wich is redicilously expansive and probably not worth that money,

even if i do so,do i also need to put in a different command to load a different formatted file?

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55 minutes ago, johannesmutlu said:

Well i indeed don’t know anybody in my neightborhood who owns a 1571 diskdrive,but my local gameshop down the city may do have one sothat i can buy it for testing it,but if they don’t have (wich i assume) then i probably need to fork over a whopping $385 dollars + €58 shipping costs on ebay ,wich is redicilously expansive and probably not worth that money,

even if i do so,do i also need to put in a different command to load a different formatted file?

IF it is the case the disk was created on a 1571 using the head swap command then, yes, you will have to use unreasonable commands to access the second side.  Again, IF this is the case, the reasonable solution and way to avoid this situation is to create the disk properly in the first place.

 

If you have access to someone else with a Commodore system even if just a 1541 drive, you could prove the seller wrong by creating a flippy the proper way on the other system then test it on yours.  Testing her disk on the other system would be greatly helpful, as well.

 

If I were you, I would start a case with eBay to return the item and demand a return shipping label.  Of course, I do not know what the policies or laws might be governing this in your country.  At the very least, you have access to half the disk so get half your money back.

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