At 2005-08-15 12:09, Jens Schoenfeld wrote: >At 18:29 14.08.2005 -0800, Jaap van Ganswijk wrote: > >>Don't confuse the real floppy controller chip and the software. >>The chips still can read FM disks and by the way, MFM and FM >>(or DD and SD) use the same medium, but use it in a smarter >>manner. >> >>(And building FM into an MFM controller costs almost nothing, >>so they do it in the spirit of that every new PC has to be >>completely downwards compatible with every old PC. > >Unfortunately, this doesn't seem to be true for the VIA chipset of my >computer. I do have software that tries to read FM, but it was not successful >with these disks. Worked fine for many MFM formats where the bitrate was >standard, but not with these disks.
Disk rotation speeds weren't standard in the early 80's. But MFM and FM should work the same on any medium, because MFM is just a smarter way to use the medium, but doesn't require any difference of the medium or the technology. Of course FM support might die out slowly because nobody uses it anymore, but I'd still like to be able to read my SD floppies. >>3.5 inch disks are logically identical to 5.25 inch >>disks. > >Not exactly - the rotation speeds are different, And that is why I wrote 'logically'. To the PC it's not relevant (and actually unknown) how fast the disk rotates. (It could measure it, but that isn't relevant for the operational process). What is relevant is the speed with which the bits arrive etc. >but this VME computer doesn't see that at all, VME is the keyword here: Check the the VME standards. VME is an Motorola oriented bus standard. >because the floppy drive has a built-in controller (comparable to the LS-120 >super floppy for ATAPI). As it should have. It's silly to have a controller on a PC motherboard handling a floppy drive using analog signals via a 40 cm cable. These sensitive things should be handled locally. >>>Thanks for your other hints - I have also seen quite a few filesystems >>>before, but never really tried to hack one. One way or another, I managed to >>>get hold of a documentation, so I had the positions for sector pointers, >>>directory entries and so on. >> >>So what is the remaining problem? > >Sorry, there's a misunderstanding: I've had documentation for all the other >filesystems I've been working with, but I don't have documentation about >VERSAdos. I've passed along Uwe's link (thanks for that!), hoping that it's >really related to CP/M (which is not the case, according to your answer). >Should you have some kind of documentation for any Motorola filesystem, any >hint is very welcome. Sorry, I have never seen Motorola as a serious OS or FS writer. >>BTW. I never wrote a 68000 emulator, because it has a very >>chaotical instruction set and it was 32-bits and I was still >>writing the emulators on an 8/16 bits system. > >There are nice 68K emulators out there, the most interesting being in the >Amiga emulators: It's a JIT compiler, beating any real 68K processor. A few >years ago, the Amiga with a 68060 accelerator and a MAC emulator was the >fastest 68K-Mac you could buy, but today, it's an x86 computer with the >just-in-time-compiler. Sad but true... I can't be sad about the 68000 architecture dying. It was such kitsch. -- Author: Jaap van Ganswijk INET: [EMAIL PROTECTED] Fat City Hosting, San Diego, California -- http://www.fatcity.com --------------------------------------------------------------------- To REMOVE yourself from this mailing list, send an E-Mail message to: [EMAIL PROTECTED] (note EXACT spelling of 'ListGuru') and in the message BODY, include a line containing: UNSUB CHIPDIR-L (or the name of mailing list you want to be removed from). You may also send the HELP command for other information (like subscribing).
