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Post by donno128 on Apr 21, 2015 20:47:47 GMT
I have some unflippy disks, that is, 1541 disks that are two sided
but you don't flip them. The second side can only be used
on a 1571 in 1541 mode with h1 enabled via "u0>m0" and "u0>h1".
They are handy for not having to flip over a disk, or increasing storage
without having to notch the disk and have it spin backwards when
you turn it over as on the 1541 or other single sided drives.
Or hiding information on the second side from 1541 drives and such.
So I tried to create one in VICE X128. No luck.
Created a 1571 image, then tried forcing 1541 mode and formatting the
second side to try to get a usable image on the second side via
m0 and h1 thinking I would then reformat the first side. I guess it can't be done?
It works in the real world on real hardware but on the emulator I cannot
archive my disks as .dxx images that would work as two side in
unit 8. Maybe just use opencbm and DOS commands would
work for the transfer but would VICE recognize it and if so how?
Does anyone know?
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Post by hydrophilic on Apr 23, 2015 8:13:48 GMT
Based on my old experience of VICE Source Code (never peeked v2.3+), there is no way to use "unflippy" disks... to use your terminology...
Just so we are clear, you are talking about accessing the "back" side of a floppy disk using non-standard method (1571 / u0>h1)...
I've played with this in real hardware... never *really* used it because it relies on 1571 drive (not portable)... but ANYWAY it seems this trick does not work in VICE... my opinion/experience... please post if you have working method!
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Post by donno128 on Apr 23, 2015 19:46:00 GMT
Yes, accessing the back side on the 1571 10 OPEN 15,8,15,"U0>M0" 20 PRINT#15,"U0>H1":CLOSE15 U0>M0 because it has to be in 1541 mode... Maybe a 1541 could be made to spin backwards to read them; flip disk and read side b by spinning disk backwards. data comes in the correct direction... How hard can it be?  (Having never heard of it being done myself...) and no... I haven't found a working method. I use these to keep my 1541 disks the same while using the second side without notching. I don't have a disk notcher and have bunged up several disks with hamhandedness or plain not watching what I'm doing. |
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Post by hydrophilic on Apr 27, 2015 6:07:36 GMT
Yeah, that is what I thought you meant... played with it myself so know it works on real hardware... Never used it seriously; I guess best use would be for some 1571 copy-protection?
I normally just notched the disk ... usually with a pair of scissors... it was very rare I would have a hole-punch available, and never owned a disk-notcher.
One time I got creative and put a switch on the drive to ignore the write-protect-notch... worked great for a year or two until it bit me in the a$$ with a game you may have heard of "Airborne Ranger"... well somehow in the "Create Game Save Disk" process I managed to destroy track 18 on the front side of the original game disk... needless to say I could never play it again on real hardware (I can enjoy it today thanks to emulators)
Err, on-topic, this feature is broken in older (before v2.3) VICE versions ... the emulator code just can't handle it... I haven't looked at modern VICE source code, but I would be surprised if it worked (considering the other existing problems with 1571 emulation).
Now making a 1541 drive spin backwards to read such a disk would be a neat trick... be sure and give us a full write-up if you try this... Succeed or fail, it would be a great story!
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Post by donno128 on Apr 27, 2015 16:02:52 GMT
Unflippy could be good for a self booting disk that has MFM format on flip side, setting it up to be read or written to, maybe a little disk based MFM access system.
After I thought about the spin backwards thing I tried to find an example of someone else doing it. My forays into hardware alteration are few and far between. The guy who wrote ummm... I think it was called DOS 5.0, mentions it but doesn't say he did it. That's a package that can read and write MFM disks on a 1541 with hardware alterations.
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Post by hydrophilic on Apr 28, 2015 6:53:21 GMT
I wrote a hack to an old version of VICE (1.7, 2.0 ? who knows) that implemented my own custom disk format "X1571"... this format would support *almost* any combination of GCR and MFM on the same disk... it would surely handle your "un-flippy-disk" and your "side1-CBM/side2-MFM" format... the only thing it could not do is support MFM and GCR on the same track! I got it to a fairly reliable/working state... but then, somehow, I *ROYALLY* fouled up the code such that it would no longer compile... Since there was no motivation in the Commodore community, and I had no real need for this "feature", I abandoned the project... But I can try to resurrect the source code if you ask... just know it is a based on a relatively old VICE version (in particular, no 2MHz support). Actually, VICE (as far as I know) does not truly support MFM in the 1571 code... well that is what I remember from v2.2- source code... So my X1571 format my be good for "real" (although obscure) disk formats... anything that uses MFM... [Edit]Because VICE, nor any emulator that I know, can mix GCR and MFM on a "1571" disk image, it seems like a great way to implement copy-protection (or at least, emulator rejection). Please contact me with a ridiculous royalty offer if you would like this form of "copy-protection" for your up-coming "mega hit viral game"  [/Edit] |
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Post by donno128 on Apr 29, 2015 19:11:27 GMT
With your X1571 format besides conquering
REAL HARDWARE WORLD (Earth) we could also conquer
EMULATOR WORLD (Simulated Earth)!
Confession: we like Pinky And The Brain here...
I see it as a needed component but apparently the rest
of the world doesn't. That may have something to do with
the relative rarity of actual 1571 drives, which were
interesting/marketed only to the apparently underappreciated
user base of C128 users.
** VICE 2.2 (what I use) and VICE in general I suggest
strongly is lacking if it doesn't handle documented drive
characteristics.
I normally use my real hardware, so I guess no need to
resurrect that code for VICE on my behalf.
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Post by hydrophilic on May 2, 2015 14:04:09 GMT
donno128, I like your positive attitude... (plus the Pinky and the Brain)! However, I am confused about your thoughts on implementing a software/emulated solution... you seem to say it would be nice to have but also needless/irrelevant. Can you clarify? MFM is rather obscure on the 1571, so I agree it is not a great concern/priority for emulators. On the other hand, the 1571 is the only floppy drive in history (my limited experience) that supports 2 hardware encoding methods... So I think emulating all the 1571 possibilities would be great for educational/historical purposes. But it takes a lot of effort, and I don't think I'll find the time to complete my X71 format (anytime soon) unless there is large demand from the CBM community... (I like to think when I retire, I will finish all my incomplete projects... but can we wait? and will I be compentent in the end?) |
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Post by motrucker on Aug 17, 2015 17:57:19 GMT
donno128, I like your positive attitude... (plus the Pinky and the Brain)! However, I am confused about your thoughts on implementing a software/emulated solution... you seem to say it would be nice to have but also needless/irrelevant. Can you clarify? MFM is rather obscure on the 1571, so I agree it is not a great concern/priority for emulators. On the other hand, the 1571 is the only floppy drive in history (my limited experience) that supports 2 hardware encoding methods... So I think emulating all the 1571 possibilities would be great for educational/historical purposes. But it takes a lot of effort, and I don't think I'll find the time to complete my X71 format (anytime soon) unless there is large demand from the CBM community... (I like to think when I retire, I will finish all my incomplete projects... but can we wait? and will I be compentent in the end?) These days I only use 1571 drives. But I use them with real hardware. I don't care for vice, never did. These disks, whether flippy or not, are almost irrelevant themselves these days. I just recently bought one of these devices, the UK1541 which really makes it so the real disks are used only to archive the software for the SD cards. www.retrocollect.com/News/sd-card-loading-uk1541-adapter-announced-for-commodore-64.html |
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Post by hydrophilic on Aug 21, 2015 12:50:43 GMT
I agree, motrucker, once you get a device that can read SD cards, emulation becomes less important..
But there are still some disks that rely on MFM format (rare, except for CP/M), or GCR format (most commercial software), or some bizzare combination (only home-brewed stuff... correct me if I'm wrong).
Anyway, glad to hear you are hacking away with real hardware... (envious)
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