Amiga.org
Amiga computer related discussion => Amiga Hardware Issues and discussion => Topic started by: Crackdown on September 03, 2005, 02:32:29 AM
-
Howdy!
Just can't understand :-? ... without catweasel no one can use pc floppy to write amiga disk... uhn... and the only explanation is controller - sorry but until I understand for me is n*sense. Why? Well - unless phisically the drive can't write, we can overide the pc controller as example:
Old x86 fdd and ide isa controllers,
Recent usb fdd drives,
By software like hd-copy that control dma and buffer
etc...
Never heard about using a pc floppy to replace a amiga one?
You can even format a disk in ms-dos with format a: /t:80 /n:11 to get 880K!
So please if i'm wrong i would like to know. And don't forget that catweasel is a controller too!
Thank you cya!
-
get something called CrossDOS... it enables you to read/write MSDOS disks..works great. if I'm not mistaken.. from WB 3.0 and greater you can mount PC0: and read/write to those disks also.. I dont remember about 2.x though.
-
Thank you for so fast response!
But CrossDos is for Amiga. I know that amiga can read ms-dos 720k or if you lucky HD ones. So pc should be able to do the same by software - i think...
Cya
-
@Crackdown
Just can't understand ... without catweasel no one can use pc floppy to write amiga disk... uhn... and the only explanation is controller - sorry but until I understand for me is n*sense. Why?
PC floppies have gaps between sectors of a track. Amiga track is single blob of data with no gaps. It does still have the sectors in it (11) but directly after each other.
PC controller cannot write data without these gaps.
old post about the matter (http://www.amiga.org/forums/showthread.php?t=1758)
-
So bypass the controller and it's possible... uhn do you know any homebuilt fdd controller for x86? I believe that it could be easy to advance in this matter - catweasel example :) Anyway the old post give me new info about the way that IBM and commodore writes the same 880k - behind the smaller sector gaps, amiga can write an entire track at once. Have you heard about fdutils (http://fdutils.linux.lu/disk-id.html)? I still believe (but have to read) that it could be done only by software. Thank you!
-
No it can't be done in software. fdutils won't help. It's still limited by the hardware limitations in the fdd controller.
-
When you tell the floppy drie on a PC to say, read a track. The drive then reads the raw data off the disk. Then the floppy drive controller is a microcontroller that then decodes the raw data sending back to you the decoded data you want. On the Amiga, when you do this, you get sent back the raw undecoded data from the disk, you then must decode it in software. This does give the cpu a little more burden (that isn't very amiga like but that's the way it is) but it does make the amiga more flexible (I think some games even had their own custom encoding format).
So Amiga disks are encoded differently from PC ones so the PC floppy drive controller can't understand what it's getting from the disk.
srg
-
So x86 use hardware and amiga software to R/W data. True - there are progs that use software to comunicate by floppy led. I will learn more about pc controllers, and if hardware is the soluction - thats the way to go! If catweasel works (and note that schematics looks more complicated because other board features) i believe that a low-level hard/soft interface could be done. Anyone with deep electronics know-how feel free to contact me ehe. Thank you guys for your replys!
-
Crackdown wrote:
If catweasel works (and note that schematics looks more complicated because other board features) i believe that a low-level hard/soft interface could be done.
Huh? are you saying you've got the schematics to the catweasel?
If you're really interested, have a search on Amigaworld.net, as Olegil was brainstorming an idea about creating a USB-Floppy adapter that could read/write Amiga disks.
-
Oh no - it was just an example that confirms that could be done - just a point. About catweasel i don't have schematics but everyone could get them - better - draw them - the problem are the IC's assembly or anything they use to code :) and this is illegall of course but could be done maybe with some reverse. Don't care.
I've been checking and found some usefull info like Amigablog (http://www.techtravels.org/amiga/amigablog/) and maybe don't have to do anything from scratch. I will check too the olegil project and I leave here a appeal (sorry my english) to all folks that can contribute to do so. Things like this are keeping REAL amiga alive and I don't want to surrender to some emulator and buy things that should already be public domain from cl04nto. This is becoming a long post... cya :)
-
Err two small questions - I searched amigaworld.net and I found the olegil project... better - the poll about if that project deserves to go ahead or not - nothing more nothing less so:
1- Is the project really running?
2- There's any url for it?
Can't find any more info
Thank you!
-
@Crackdown
Err two small questions - I searched amigaworld.net and I found the olegil project... better - the poll about if that project deserves to go ahead or not - nothing more nothing less so:
1- Is the project really running?
2- There's any url for it?
Can't find any more info
Thank you!
Few friendly hints:
1. Create a new thread for new topic.
2. Use descriptive topic (Subject) for the thread.
-
??
As matter of fact I think this is not a new topic - and as I see there are LOTS of threads with persons looking for a way to write amiga floppy on pc. So why create new threads? For amiga.org ego about number of threads? Don't think so... If people could acess all answers about a subject or related one in just one topic isn't better than reading tons of threads? That's why about 2 or 3 days the same question is posted because most of people don't want to browse hundreds of post and replys. Don't get me wrong - i really agree that topic must be descriptive.
I was expecting some kind of answer but not this one lol - no problem... all fine.
And at least I understand why donald duck was censured (just a joke) :)
A big hug to you!
-
Catweasel is the only way it's possible to WRITE an Amiga Floppy. Tho I do recall a hack allowing you to connect an external Amiga floppy drive to the parallel port for read access.
The format Amiga uses on floppys is similar to that of a CD, rather than in sector form like a hard drive. This is the same for double density (880k) Macintosh disks. It's impossible to get a PC floppy drive to move the way it needs to to correctly access these spiral tracks, without using some form of hardware to alter the way the drive heads move. Software alone can not accomplish this because it was never meant to be done with a PC floppy controller.
-
srg86 wrote:
On the Amiga, when you do this, you get sent back the raw undecoded data from the disk, you then must decode it in software. This does give the cpu a little more burden (that isn't very amiga like but that's the way it is)
Actually most of this decoding used to be done by Blitter - without much CPU load AND flexible software decoding - THIS really was the Amiga way! :lol:
-
@Zac67
So paula do the I/O job and Agnus (Blitter)do the MFM with software?. The asynchrone amiga floppy manner is due Blits? Or the Paula emulation is the key? Sorry about questions :)
-
Paula does the analog <-> digital bits, very basic channel en/decoding stuff. The raw data is transferred to a CHIP-RAM buffer where the MFM <-> data stuff is done by Blitter and 68k (Blitter probably doing the sync searching and bit shifting stuff, 68k doing the header/data separation).
If you use 1541 disks in a 5.25" drive (GCR encoding instead of MFM) the Blitter's most certainly no use, so the CPU has to work a bit more.
btw: A CIA does the I/O control of the FDDs (head stepping/selection, r/w switching etc.) - so there's quite a bit of team work involved. ;-)
Edit: Completely forgot about Gary: HE does the write protection, motor on/off controls - even more teaming up.
-
Holy crap, if you trace it all down, it takes a little of almost every custom chip on the Amiga just for floppy funtions! Even Agnus/Alice! I'd say all, but I don't see any connections to Denise/Lisa. Man our floppy drives are COMPLEX!
-
Looks like we need all amiga IC to floppy work - lol. By the way - There's a really nice aproach to the job here - amiga floppy blog (http://www.techtravels.org/amiga/amigablog/). Thanks for your replys!
-
Hey,
Thanks for the compliment.
Yeah what I'm currently creating is an external USB-attached Amiga floppy drive controller. You'll use a standard amiga floppy drive. There will be Windows software to copy the disks.
I use a Parallax SX microcontroller and Ramtron's FRAM for temporary storage of the track.
It's still in the beginning stages, and there is much work to be done, but you can follow my progress at the low level on the blog available in the above post(s).
kamiga
P.S. Most of the hardware stuff, aka stepping/moving the heads, and even the MFM encoding/decoding is relatively simple once you get your hands dirty.
-
Why bother? Just let the amiga make the disks.... Transfer the data from your adf's over the serial port from the pc to the amiga.
Somebody earlier posted a good link on how to do this, it's on this page:
http://homepage.uibk.ac.at/homepage/c725/c72578/amiga/adfsenderterminal/methods.html
-
Not sure if the "Why bother?" comment was intended for me, but I'll answer it anyways.
Imagine you have 2000 amiga floppies. And you want to create .ADF images to archive them on a CD, and also to use in various emulators. How do you do it?
There is no easy, fast, noncommercial way of imaging the amiga floppies on the PC.
Since PC's can't read amiga floppy disks, you must create .ADF's on the amiga first, and then transfer them to the PC. After they are on your amiga, assuming you have a HD, you have to have some way to get them to the PC. Your only available port is the serial port (you could use parallel but this suffers the same problem), but its horribly slow. Like 33.6kbps reliably on an A500. Or perhaps a little better. Also, although the amiga does a pretty good job of reading floppy disks, an external controller can do a considerably better job, spending more time, allowing for more retries, etc -- with overall allowing for slightly less strigent timing requirements, etc. Amiga floppy drives(and the disks) are also aging, and this will produce less than perfect results. Now imagine you can correct for this in software on a controller.
Plug-n-play USB to the PC with some GUI software, and the amiga drive on the other side. Simply pop in disks, read them faster and more reliable than any amiga could read them, and have a bunch of ADF's ready to go.
And heck, learn a little bit about how microcontrollers and amiga floppies work in the process? It's a win-win situation.
-
I'd say it's definitely worth bothering! Look at how many PC-based Catweasels have been sold for the exact same purpose.
I have a Catweasel and like the fact that I can easily and reliably read/write Amiga disks using a brand new standard disk drive rather than one that's 10-20 years old...
Good luck with your USB drive project - if you complete it and can provide a driver to allow the drive to be used as DF0: from within UAE/E-UAE/WinUAE, you've got yourself a customer!
- Ali