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From: perry@well.UUCP
Newsgroups: comp.sys.amiga
Subject: Re: ASDG Floppy Accelerator (and other rumors)
Message-ID: <3153@well.UUCP>
Date: Tue, 26-May-87 15:22:10 EDT
Article-I.D.: well.3153
Posted: Tue May 26 15:22:10 1987
Date-Received: Thu, 28-May-87 05:41:51 EDT
References: <6805@amdahl.amdahl.com> <1912@cbmvax.cbmvax.cbm.UUCP>
Lines: 43
Summary: Facc Implementation Details

In article <1912@cbmvax.cbmvax.cbm.UUCP>, daveh@cbmvax.cbm.UUCP (Dave Haynie) writes:
> There was a thread about this going on in BIX awhile ago, at least I think
> that's what this product refers to.  Simply put, its a program that adds
> intelligent track caching (i.e. at the device level) instead to DOS's block
> caching.  Also, the caching memory can be FAST memory; its not required to
> be chip memory as are normal floppy buffers or DOS's block caches.  From
> what Perry said, you have the power to add or remove caches at any time.
> With enough tracks cached, you get what essentially amounts to a RAMdisk
> overlay of a floppy disk.
> -- 
> Dave Haynie     Commodore-Amiga    Usenet: {ihnp4|caip|rutgers}!cbmvax!daveh

Facc (available now at dealers near you or direct) is in fact an intelligently
managed buffer pool. The pool exists and  is  shared by all drives in the same
way that a Unix system's buffer pool is shared by all drives. That is,  as one
drive becomes  more heavily used it will begin reusing buffers previously used
by other drives.

Facc presents a graphic  display detailing exactly what's going on in the buf-
fer pool so that you can tailor  the size of  the  buffer pool to greatly opt-
imize any particular recurring operation which you might have.

The caching is by sector not by track. Writes  are written  through the cache.
Disk removal causes automatic cache invalidation for that drive. 

One interesting but  pleasant anomoly is that Facc searches 500 or so buffers
faster than AmigaDOS  searches  16  buffers  allocated using addbuffers. This
can be explained by the data structures used by both implementations.

We suggest that NO addbuffers buffers should be employed whenusing Facc since
they are a) redundant b) slower c) come from Chip ram.

As Dave Haynie suggests, the really  neat  thing  about Facc is that it gives
you ram disk  like  performance  from a very stable basis (a real floppy) and
at the same  time is more efficient (ram wise) than a ram disk for low memory
applications. (ie:  when  you  haven't  got MANY megabytes of ram to throw at
a ram disk - Facc is a better  bet  since  it only caches what you are REALLY
using unlike a ram disk which ``caches'' everything.)


Perry S. Kivolowitz
ASDG Incorporated
(201) 563-0529