[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index]

Re: Hardware musings

Michael J. Mahon wrote:


But I thought part of the problem was making it possible for a user
with protected disks, but inexperienced in deprotection, to be able
to image their disks with some assurance that everything needed to be
able to run them under emulation, or duplicate them, has been captured.
But they can. Just copy everything... Once preserved, someone could analyse the disk image and recreate the original to deprotect it or just to make a new disk. (Good luck _writing_ every quarter track and have the thing usable when through.) 


I'd like a method that works for *everyone*, with or without an
Apple II (if they use the OP's notion of a microcontroller-controlled
drive connected via USB for the capture).
Even without an Apple II... Wow, that's ambitious. I just don't see that happening unless someone comes up with a diskette reading mechanism that does proper CGR.
But ONLY the spiral images would contain that much information. Most disk images will not. 

So, you're willing to let a little matter of 4x storage space stand
in the way of capturing images of disks that you may never see?
Never. But why store so many tracks of data if you aren't going to need them. Most (read 99.999%) of A2 disks would capture perfectly sticking to the 80 (72) tracks the standard disk drive is capable of doing without trickery. If for no other reason than the width of the head precludes missing quarter track info. It's the synch that's a bear. 


Let's see--10,000 protected disks, at about a megabyte apiece for a
completely uncompressed (unlikely) representation of *everything*,
adds up to 10GB--two DVDs or a tiny sliver of a recent hard disk!

Why should anyone worry about a 1MB image size today?


No one would.



The .pdf of the documentation and game materials may be bigger!  ;-)



And usually WAY bigger.  :)


Actually, you can't guarantee rotational uniformity to anywhere near
the length of a bit on a track, so if data was written with a non- standard-width head, it can't be written with a standard-width one.
Recreation of some original disks in it's original analog format is impossible without specific special hardware. So recreation becomes irrelevant so long as the data was captured and the disk image is usable in an emulator. Maybe later hacking could reproduce a copy that works, but that's not what you want. 


Interfacing an HD drive with its thinner head is a fun idea--though
there are rotational speed differences, too.  It would be easiest to
"gut" the drive electronics, as Woz did with the SA400 drive.
Granted there are rotational differences, as the tracks are longer or whatever, but on the 5.25" drive they are all the same angular width. :) 


Retrofitting an HD head on an Apple drive is an interesting idea, but
more for the mechanically inventive.  ;-)
Definitely not for the feint of heart. Plus the magnetic properties are a bit different. It may read but would probably not write properly for a normal drive to read. 

Thankx,
Ed