ckp@grebyn.com (Checkpoint Technologies) (11/18/90)
In article <1990Nov16.215210.23026@daffy.cs.wisc.edu> pochron@cat37.cs.wisc.edu (David Pochron) writes: >Why not just write a GCR-trackdisk.device that writes disks in GCR format >instead of MFM format? You get twice as much disk space (880*2 = 1.66 megs I >think - its been a while since I last read the disk drive section in the >hardware reference manual!) and you only have to live with the fact that reads >and writes will be twice as slow. Using a trackdisk.device with a compression >routine would probably work much slower - especially on a 68000 machine, but >would give different results from different files. Sorry, it won't work that way. GCR will actually give you the same storage density as MFM. Why? Because you must reduce the bit rate to use GCR. MFM coding ensures that two 1 bits will not be recorded in a row, whereas GCR makes no such promise, therefore you must reduce the bit rate to half. At least, if you want to use the same media and disk drives, you must... I've never been able to get a Commodore engineer to comment on this idea of mine, but what if a person used a GCR format in 2us bit rate, and connected a quad-density floppy drive? Will this confuse Paula's PLL if it tries to handle GCR format in high speed? I don't have the resources myself to test this. (If someone would send me a free 1.44 Meg 3.5" floppy drive, I'll give it a try. :-) -- First comes the logo: C H E C K P O I N T T E C H N O L O G I E S / / \\ / / Then, the disclaimer: All expressed opinions are, indeed, opinions. \ / o Now for the witty part: I'm pink, therefore, I'm spam! \/