gt0t+@andrew.cmu.edu (Gregory Ross Thompson) (04/13/90)
tm@polari.UUCP (Toshi Morita) writes: > If I remember correctly, Br0derbund's spiral tracking (a la Choplifter) used > adjacent half-tracks in concentric half-circles to achieve one of the most > difficult copy-protechtion schemes ever, (not quarter tracks). The spiral tracking protection method was called Spiradisk, and invented by a guy named Mark Duchaineau. It loaded about 20 times faster than DOS 3.3 did. There were two main problems with it. The first was that it took up about half of the disk. The other was that the disks often had to be rebooted once or twice before the program would load. It was first used on some of Sierra On-Line's software. > Nice to see all the slick programmers (kadickey, nicholas) on Usenet! Yeah, it sure is... > Toshi Morita > ..!uunet!microsoft!uw-beaver!sumax!polari!tm -Greg T.
fadden@cory.Berkeley.EDU (Andy McFadden) (04/15/90)
In article <oa9FU=i00WB4MCQldj@andrew.cmu.edu> gt0t+@andrew.cmu.edu (Gregory Ross Thompson) writes: > > tm@polari.UUCP (Toshi Morita) writes: >> If I remember correctly, Br0derbund's spiral tracking (a la Choplifter) used >> adjacent half-tracks in concentric half-circles to achieve one of the most >> difficult copy-protechtion schemes ever, (not quarter tracks). Broderbund has always had some of the best copy protection. Electronic Arts is up there, but they tended to use the same scheme over and over again. > The spiral tracking protection method was called Spiradisk, and >invented by a guy named Mark Duchaineau. It loaded about 20 times >faster than DOS 3.3 did. There were two main problems with it. The >first was that it took up about half of the disk. The other was that >the disks often had to be rebooted once or twice before the program >would load. It was first used on some of Sierra On-Line's software. ...or sometimes they wouldn't work at all. Frogger and Maze Consruction Set used this scheme, which was also pretty hard to boot-trace. A guy I know (or knew; haven't heard from him in years) bought Frogger but it wouldn't work on his disk drive (apparently some disk drives don't do quarter-tracking very well). After a small investment of time, I managed to pry it loose of the spiradisk stuff. That scheme has some interesting components... I tried to use a memory- snapshot card on it, which worked just fine unless something in the machine changed. Apparently it was scanning ROM and the peripheral slots, so that if it suddenly found itself running on a machine with a different configuration, it would flush itself and halt. At any rate, it was conceivably possible to copy the disk if (a) you used the synchronized tracks option, and (b) your drive head read a wide section of the disk. Theory was that it would read the quarter tracks on either side of the drive head, so that you could essentially copy two tracks at a time. If you carefully synchronized and interpreted the disk data, it would work. Not very well, but... >> Toshi Morita > -Greg T. -- fadden@cory.berkeley.edu (Andy McFadden) ..!ucbvax!cory!fadden