051332@UOTTAWA.BITNET (05/21/87)
Received: by UOTTAWA (Mailer X1.23b) id 1050; Thu, 21 May 87 16:04:51 EDT Date: Thu, 21 May 87 16:03:47 EDT From: John Turnbull <051332%UOTTAWA.BITNET@Forsythe.Stanford.EDU> Subject: Re: Re: 'The Russian Doll' bug To: INFO-ATARI16@SCORE.STANFORD.EDU in: tektronix!sequent!mntgfx!dclemans@ucbvax.Berkeley.EDU (Dave Clemans) writes: >There is a bug in the floppy driver in the current TOS ROM's that can >very easily cause symptoms like those described in the article ... >Basically, the problem is that while the WD1772 floppy controller does >have a built-in read multiple sectors command, that command is somewhat >brain damaged; ... >However, if you look at the floppy disk driver code you find that the >driver is using the "read multiple sectors" command of the 1772 for >all (all that I've found so far at least) floppy reads. And under >"normal" circumstances the driver tries to never reset the controller; >This works "most" of the time... But if your really trying to push >data through the system "fast" you have a non-zero chance of seeing >a timing problem pop up. >... The >best way to work around it, and still use "fast" formats, is to write >the disk in whatever way you desire, but NEVER try to read more than >one sector at a time ... >Unfortunately you don't always have control over the sizes of read >requests made by various packages... Thank you for the reply. If I knew where, I might be able to 'look' at the driver codes, but I am not convinced that I could read them. :-) (my fault, not yours). But really, this does look bad. Are you saying that TWISTER is buggy, ( in the most conservative sense of buggy: the program does not work reliably on the machine for which it was written, even if the cause of problem is due to a bug in the machine ) or that all fast format programs are doomed due to a brain damaged disk controller? I guess the real bottom line ___ is: if I make up the club DISK(S) OF THE MONTH in TWISTED or any fast read format, then make a zillion copies of the disks with some fast copy program. Do I stand a non-zero chance of being lynched? John Turnbull, NETNORTH: 051332@UOTTAWA 30 Somerset Ave, BITNET: 051332@UOTTAWA Dept. of Biology, ARPANET: 051332%UOTTAWA.BITNET@WISCVM.WISC.EDU Univ. of Ottawa, uucp: ...!psuvax1!051332%uottawa.BITNET Ottawa, Ontario, JANET: 051332%uottawa@rl.earn CANADA, K1N 6N5. ICBM: 45 25' 33'' N 75 39' 05'' W