From: HarriRehnberg@salient.com (Salient Software)
Newsgroups: comp.sys.mac.apps
Subject: Re: Times Two (was Re: Autodoubler & other transparent compression progs)
Date: 4 Nov 92 23:53:57 GMT
Reply-To: HarriRehnberg@salient.com (Salient Software)
Organization: Fifth Generation Systems
X-Mailer: uAccess - Macintosh Release: 1.5v3


In article <1992Nov4.072046.14690@netcom.com> (comp.sys.mac.apps), leonardr@netcom.com (Leonard Rosenthol) writes:
> First, as you will see in my signature, I work for a company which competes
> with the product in this article - HOWEVER, I want to put some more detail
> into this discussion.  I do not wish to slight Golden Triangle in any way,
> but simply to help users understand a new technology.
> 
> In article <1992Nov3.094642@p4.cs.man.ac.uk> brownc@p4.cs.man.ac.uk (Christopher C. Brown) writes:
> >It's called Times Two from Golden Triangle.  It works by replacing your 
> >current disk drivers with the TimesTwo drivers. After you install it, your 
...
> 	This is true - in more ways than one.
> 
> 	First, TT is a REPLACEMENT driver, not an enhancement.  That means
> that any current formatting software that you are using (SilverLining, Hard
...
> 	What this means is not only is a previous investment no longer useful,
> but you can not use the "special features" of these other drivers - such
...
> 	Second, TT uses a non-deterministic methodology for reporting the
> amount of free space on the disk.  It ALWAYS reports 2x (hence the product 
> name ;) the amount of free space on the disk - no matter how much data is
> actually compressable, it ALWAYS uses a 2x measurement.  
...
> >(and vice versa for reads).  The new driver simply translates it into 
> >*smaller* compressed binary, and vice versa.
> >
> 	Actually, TT does more than just "compress" the data - it uses a 
> number of techniques to increase the amount of "free space" on the disk
> including using dynamic "block sizes" for you disk.  This will slow down as
> disk as small blocks (which mean more free) means more to read, and so things
> slow down.
> 
> >Since it works at such a low level, it is (i think) inherently compatible 
> >with anything. It only really interfaces with the toolbox routines in ROM, 
> >so all applications (they all work with the toolbox) work correctly and see 
> >no change.  
> >
> 	This is true for applications - there should not be any (or very
> little) specific application compatibility.  HOWEVER, compatibility with
> hard disk utilities will be a problem.  Things such as DiskLock & AME which
> protect/encrypt the disk will not work in conjunction with TT.  Also, a 
> disk optimizer may cause unpredictable results since the driver has special
> block size rquirements.
> 
> 	Also, if your hard disk goes bad (for whatever reason), you have to 
> run a special "recovery program" BEFORE running whatever utility (Norton, CPS, 
> PU) you would normally - that means carrying an extra disk in your emergancy kit.
> 
> >Summary:  I think it's brilliant.  I was laughing at the demo it seemed so 
> >simple and obvious.
> >
> 	There are some definate advantages to a driver level compressor
> (though I don't belive TT has done it correctly, while others have), and
> there are also disadvantages as I've tried to point out above.  Also, another 
> important issue is "backing out".  Should you choose to back out of a driver
> level compressor, you MUST back up the drive, and completely reformat - it
> is not like removing an INIT based compressor like SpaceSaver or AutoDoubler.
...

Gee, Leonard. You sure seem to know a lot about the internals of a
competitive product (TImesTwo) that hasn't shipped yet. Are you clairvoyant?


Sincerely,
terry morse
Compression Products
Fifth Generation Systems

for all FGS products FIFTHGEN@aol.com
for AutoDoubler & DiskDoubler techsupport@salient.com
Newsgroups: comp.sys.mac.apps