Hi.
I have two FDS drives. Both are not write protected (one initially uprotected, one modded). Both can read original licensed disks without any problems.
But something weird happens when I'm writing disks. When I write disk using the first FDS drive it works great on the same drive. But the second FDS drive can't read it! And vise-versa: disk written on the second drive is not working on the first. Error 22 or error 27 appears.
I tried the Disk Keeper, Disk Hacker II and my Dumper/Writer (https://github.com/ClusterM/famicom-dumper-writer) with RAM adapter - result is always the same.
At first I through that it's some calibration problem of one of the drives, but I found third FDS drive and it also can't read disks written by the first and second drives.
I tried to read disk using RAM adapter and dumper: CRC error on first block (disk header block). First few bytes are ok and garbage data follows.
What can be wrong? Why is this happening?
Have you tried with a one-sided game like SMB, using the same RAM adapter for each drive when testing?
Quote from: ericj on February 22, 2021, 12:22:06 pmHave you tried with a one-sided game like SMB, using the same RAM adapter for each drive when testing?
Yes, i did. I've used the same RAM adapter all the time.
Have you tried making disk images and comparing the 3 disk images. Try a loading them in a hex editor and see if they are showing the same data, but the bits are shifted.
Example
Drive 1 shows 10111011
Drive 2 shows 01011101
Drive 3 shows 00101110
Or see if you see *NINTENDO-HVC* at the same area on the images
Quote from: SteveP256 on February 28, 2021, 02:03:39 amHave you tried making disk images and comparing the 3 disk images. Try a loading them in a hex editor and see if they are showing the same data, but the bits are shifted.
Example
Drive 1 shows 10111011
Drive 2 shows 01011101
Drive 3 shows 00101110
Or see if you see *NINTENDO-HVC* at the same area on the images
Data is corrupted after "*N" and i can't see any patterns.
Do the drives both appear to run at the same motor speed? Possibly the speed differ between the drives. I have two drives here one that I replaced the belt that can write (no mod) and one that I had to mod to write disks. At first the modded one would not read any disks written with the first drive. It would give error 27 every time.
What I did was adjust the motor speed (at the top of the motor). Use very very small adjustments. Each time try booting a written disk, then a original copy of a game. It takes a long time to get both drives to read each others disks, but now both my drives can read the others disk.
Quote from: SteveP256 on March 01, 2021, 06:51:13 pmUse very very small adjustments. Each time try booting a written disk
I tried to write disk on the second drive and ajust speed on the first drive in this way. Without any success :(
Hmm, I still think that it is a motor speed issue. When I was adjusting my drive I turned the motor potentiometer all the way right or left, then turned it to the half way point. If I turned it too far left it would give error 22 every time reading a disk, too far right would give error 27. Keep trying to read original disks until you see the Nintendo text scrolling up. Getting the correct motor speed is a major pain to do, took me several hours.
If you have a spare famicom and ram adapter, you could run both at same time with same copy of disk. Then you can visually see if the speed differs
If you have a game doctor and the copy master program you can read the drive speed when you adjust it.
I tried to tune motor speed of the first FDS drive without any success.
Then I decided to try a very unusual solution. I erased disk using neodymium magnet. Then I writed it on the second FDS drive and the first drive reads it without any problems now! This method works 100% of the time for any disk and any game when I'm writing on the second drive.
But this method only works partially when I write disks on the first drive - second drive fails while reading long blocks (large files), CRC check fails.
So I don't know if the second drive is good at writing or the first drive is good at reading. And it's still weird that I need to use magnet every time.
Hi Cluster,
After belt replacement, five things you need to take care.
1) Spindle Hub Alignment. It is very important.
2) Check Head Adjustment Screw (Original no need to tune). If it tuned by someone, you may need to tune it again.
3) Drive speed (I use Game Doctor's Copy Master drive speed test, speed should be 5 without disk insert)
4) Pressure cotton on the magnet head can not be too thin.
5) Clean the magnet head.
Most problem is 1) or 2), if Spindle Hub is not at right position or Head Adjustment Screw tuned at wrong place. Then the copied disk only can read by the drive which copy it.
You can read here : https://www.famicomdisksystem.com/tutorials/fds-repair-mod/belt-replacement-adjustment/
Last, you should have some original disk for test.
Hope this help.
How are your drives modded for writing and which chips (7201 or 3206) and power board revisions do they have?
Quote from: Tomy on March 07, 2021, 08:54:10 am1) Spindle Hub Alignment. It is very important.
Seems like it's aligned very well on both drives. This way:
(https://www.famicomdisksystem.com/wp-content/uploads/2011/01/Spindle-Alignment.gif)
Quote from: Tomy on March 07, 2021, 08:54:10 am2) Check Head Adjustment Screw (Original no need to tune). If it tuned by someone, you may need to tune it again.
I haven't touched it and seems like nobody adjusted it. There is red glue all around the screw on both drives.
Quote from: Tomy on March 07, 2021, 08:54:10 am3) Drive speed (I use Game Doctor's Copy Master drive speed test, speed should be 5 without disk insert)
I tried to change the speed of the first drive so that it reads a floppy disk written by the second drive, without any success. Both drives can read original disk without any problems.
I tried to write Copy Master to disk but FDS can't run it without Disk Doctor. I can't understand how to use it. Can I download Disk Doctor ROM somewhere or I need some extra hardware?
Quote from: Tomy on March 07, 2021, 08:54:10 am4) Pressure cotton on the magnet head can not be too thin.
I'll check it.
Quote from: Tomy on March 07, 2021, 08:54:10 am5) Clean the magnet head.
I will do it, thanks.
Quote from: Tomy on March 07, 2021, 08:54:10 amYou can read here : https://www.famicomdisksystem.com/tutorials/fds-repair-mod/belt-replacement-adjustment/ (https://www.famicomdisksystem.com/tutorials/fds-repair-mod/belt-replacement-adjustment/)
I read it already.
Quote from: Tomy on March 07, 2021, 08:54:10 amLast, you should have some original disk for test.
Original disk works perfectly on both drives for reading and writing. Also game saved on the first drive works perfectly on the second one.
Quote from: ericj on March 08, 2021, 08:38:26 amHow are your drives modded for writing and which chips (7201 or 3206) and power board revisions do they have?
The first drive has a FMD-POWER-03, it has not any protection (see https://www.famicomworld.com/forum/index.php?topic=15024.0) and a 7201.
The second drive has FMD-POWER-04, it's modded by me using this guide: https://famicomworld.com/workshop/tech/fds-power-board-modifications/. And it has a 7201 too.
Hello Cluster,
Last thing I want to ask is, the disk you use to clone/write is original disk ? If it is not original, then the copied disk may only can read by the drive which copy it.
Seems, you do all the things from my post above. Then I have no idea what is the problem now.
If you can fix your problem, I want to know it too. Thanks.
Quote from: Tomy on March 08, 2021, 01:24:02 pmHello Cluster,
Last thing I want to ask is, the disk you use to clone/write is original disk ? If it is not original, then the copied disk may only can read by the drive which copy it.
Seems, you do all the things from my post above. Then I have no idea what is the problem now.
If you can fix your problem, I want to know it too. Thanks.
Seems like those disks are original or rewrited original.
You cannot see attachments on this board.
Can you help me with Copy Master? Can I write it on disk using dumper/writer or I can't run it without extra hardware?
Also I will receive more FDS drives soon for tests.
Copy Master only works with a game doctor. If you don't have one, you can't use it.
hello,
Yes, your disks are original disk. Then I have no idea why you face that problem 🤔
Copymaster can copy to disk or emulate by FDSSTICK. But it need special Hardware to run it.
Does the Game Doctor ever connect to the Expansion port of the RAM Adapter in some way? The reason I ask is because I have been analyzing the Copy Master disk and it does write to $4026 several times. $4026 is the output register of the Expansion port, and there's no reason to write here if nothing is connected to it.
Hello,
Good find. But I'm sure it is no use for end user. I beleive it is test code for BUNG internal use. Or maybe they have device for it ??
Can you provide more info for it ?
I don't really have much information about it. The Nesdev wiki (http://wiki.nesdev.com/w/index.php/Family_Computer_Disk_System) have everything I know about the FDS. I did a quick disassembly of the Copy Master FDS disk image and saw it writing the content of RAM register $00F9 to $4026 in the initialization code and in a few other places, and thought it was weird. I checked the wiki and $00F9 is used by the BIOS to hold the last value written to $4026, so maybe it's just a compatibility thing done in case an Expansion port device is used or something like that. In one place it writes a value pulled from stack instead of writing the content of $00F9 though.
The reason I'm looking at Copy Master is to figure out how it measures the drive speed. If I could just learn how it's done, I believe I should quite easily be able to make a homebrewn drive speed measuring program so that people don't need to own a Game Doctor and Copy Master for disk drive maintenance in the future. It would be an FDS file that can be loaded via an FDSStick, or be written to an empty disk.
Although I can make my own Famicom programs I'm not really an engineer and unfortunately I suck at disassembly and reverse-engineering. I found the init code I think, but it jumps to a place, cat-knows-where, and I don't know how to proceed with it. It doesn't help that the disk doesn't run in most emulators. I guess I should ask the people at Nesdev for some tips.
Copy Master is quite different from a normal FDS disk though. There are only two files, and no KYODAKU-file that the BIOS normally requires (though there are ways to trick it) for example. I guess this is normal for Game Doctor disks.
Loopy reminded (http://forums.nesdev.com/viewtopic.php?p=213714#p213714) me that the FDSStick can be used for head alignment. He seems to think motor speed is less important.