excellent post there Chris,
it still amazes me that in 2012 we can't reliably emulate a simple 8-bit barely 1mhz
technology has progressed so far that a 6502 and so forth should be a piece of cake.
I've been trying to archive my own collection of c64 disks and using zoomfloppy with
nibtools,it's still not perfect for some disks.
you can actually buy the IHS (index hole sensor) for the 1541 but I haven't found any
infoto say it actually works or helps.
it seems our only chance at reliable (duplicateable) method would be to have a custom 1541
doesn't sound like much fun.
BTW - I'm still waiting for Vice (or any c64 emulator) to be able to handle serial
(rs232) properly,so you can run a BBS fully under an emulator without needing a real c64
or a modem....
Date: Wed, 4 Apr 2012 23:29:17 +0200
From: cb at kryoflux.com
To: cctalk at classiccmp.org
Subject: Re: KryoFlux and Commodore Disks
You don't want to use a PC HD drive, Commodore disks are 40 track (OK, well, 35
track, but still), the narrower head of the 80 track PC drive will cause problems if you
want to write.
Well, about 80% of the games sold for the C64 were in fact written
industrial grade PC drives with Trace machines. Many titles use 80 track
mechanics and heads. It in fact works when the drive is well aligned and
you make sure the disk is empty, e.g. degaussed, before you do this,
otherwise you would risk keeping garbage for disks that were previously
formatted in a 40 track drive with wider heads.
All games that do stepping tricks with so called fat tracks or half
tracks can't be written with 40 track drives at all.
An HD PC floppy drive will *NOT* read commodore 1541 disks.not a
chance in hell. PC drives are MFM, commodore are not. totally
You are totally wrong. The drive will happily read the disk, but you
need a controller that can make use of GRC coding and the special
encoding tricks used by copy protections. As the 1541 is a separate
computer, there is much freedom here.
I've heard of people using catweasel with
1541 drives, mounted in
their PC's also.
Really? Afaik the 80 track drives with 40 track wide heads were custom
made for Commodore and don't have a Shugart connector.
those are very different from commodore
mentioned commodore have up to 40 tracks,what about half-tracks, and
copy-protected disks? will they read v-max disks?commodore software
got heavily into copy protection,like rapidlok, and worse in the later
Indeed. These will cause trouble when read with a 1541 for various
reasons. Some protections work by using the index while recording (which
the 1541 does not have...), later read a specific track and then step
ahead to find some special data when reading a few tracks later. You
can't write such protections with a standard 1541 as it lacks the index
to aling your data to.
Other protections vary bit cell density, which is ok for reading, but
can't be written with an unmodified 1541, some make tracks so long and
write them in one pass, so you need more ram in a 1541 and some will
even trick the sync detection which is not very reliable in the 1541.
What makes things worse is that the format used for storing such data,
g64, is very badly implemented in most of the emulators out there. To
our knowledge all emulators are working with a fixed track size of 7928
bytes per track, which will give trouble for e.g. V-MAX! style disk, at
least everything before V3.
We are working with Pete Rittwage (author of Nibtools) to find out if we
can help enhance e.g. Vice to support properly imaged disks that have
demanding protections. Currently some g64s need tampering with, some
even need cracking the game, because the format can't properly store the
protection (see e.g. Pirates! for fun invloved). See:
If anyone wants to take a look... we do have V-MAX disk images of
Defender Of The Crown that are definitely beyond what emulators will
accept at the moment. Let me know...
I'd say zoomfloppy, simply because of
nibtools, which is the most
feature-rich for commodore disks I've found.especially where
copy-protection is involved. And, the fact it can write images back to
disk gives it a distinct advantage. this is only for commodore style
disks, other platforms would have their preferred tool(s). Dan.
I would agree, at least if writing is important to the person using it.
KryoFlux currently does not write g64 files, so it's for reading only
(at the moment). We do have a preliminary STREAM to g64 converter, which
spits out files that are correct in regard to what's on the disk
(leaving out e.g. varying density in a track, which can't be stored by
the file format itself), but fail in emulators, because, as written
above, all of them work with a fixed track size and so forth. Some
protections will fail if the track size is wrong.
If you are going for an estimated 85% of things out there, can live with
losing index information, don't fear messing with images, having e.g.
three to four separate g64s for one game for different emulators, want
to start tweaking the drive to alter rotation speed (therefore creating
e.g. longer tracks at the cost of slightly wrong recording coercivity),
and need a cheap solution, ZoomFloppy with a 1541 and Nibtools will work
ok. I also have one for testing, it's very well executed and Jim Brain
delivers quality. If you want to go beyond, KryoFlux might come handy.
E.g. a 1541 will never show you recording tricks like varied bitcell
width, "killer tracks" full of syncs etc. But it's work in progress, and
won't be fully ready tomorrow.
Modifying a drive to make it read flippy disks in one pass, like at the
recording stage, is a pain. Just for the record.