🚀 go-pugleaf

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