[comp.sys.atari.st] Twister

clj@SAPSUCKER.SCRC.SYMBOLICS.COM.UUCP (03/23/87)

>  From: ihnp4!inuxc!iuvax!franco@ucbvax.Berkeley.EDU
>
>                 I am not sure why the authors of twister set their formatter
>  to 400k when 410k can easily be achieved.  The following hacks to the 
>  executable will change twister to a 410k twister:
>
>  The single occurrence of HEX 0320 should be changed to 0334
>  The single occurrence of HEX 0640 should be changed to 0668
>  The single occurrence of HEX 0050 should be changed to 0052  (in third sector)

I'd feel better about doing this if some explanation were included about what
this is supposed to accomplish.  Otherwise, I can't tell if this is something on
the order of "For a real high-energy drink, substitute naptholene for the orange
juice."

(I guess from looking at the numbers that this causes cylinders 80 and 81 to be
used, but I'd rather hear it from the horse's mouth, so to speak).

I also have not noticed a measurable speedup after formatting a DS disk with twister.
I've been reading and writing VIP Professional workspace files which are about 100K bytes
long, and I do have reboot.prg in the auto folder to disable write verification.  I
haven't done enough experiments to say for certain that there is no speedup, however.

sansom@trwrb.UUCP (03/24/87)

In article <870323095359.3.CLJ@OOGLE-BOID.SCRC.Symbolics.COM> clj@SAPSUCKER.SCRC.SYMBOLICS.COM (Chris Jones) writes:
> ...I guess from looking at the numbers that this causes cylinders 80
> and 81 to be used, but I'd rather hear it from the horse's mouth, so to
> speak...I also have not noticed a measurable speedup after formatting
> a DS disk with twister...

The fix involves changing the number of tracks formatted.  I've got an ugly
version of 410K/820K Twister working now, but can't really post it because
it is definitely not in the public domain.  Once I'm through, I may post
diffs so that those of you who bought the Spring START disk can make the
change.

About the speed:  you'll only notice the speed difference when the programs
doing the disk access are "well behaved".  For instance: use a "standard"
disk to load a copy of ST Basic (yech).  Measure how long it takes to load.
Now do the same with a Twisted disk (I kinda like that sound of that).  It
_should_ be about twice as fast.  If it isn't, then your version of Twister
doesn't work (for reasons unknown).  Programs like VIP should do their disk
access using large buffers, but they don't always.  As bad as GEMdog is, it
_is_ smart enough to write large blocks of data to the disk as fast as the
disk can take them.

-Rich
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 /// Richard E. Sansom                    TRW Electronics & Defense Sector \\\
 \\\ {decvax,ucbvax,ihnp4}!trwrb!sansom   Redondo Beach, CA                ///
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