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From: asslk@acad2.alaska.edu (Kingry Shane L)
Newsgroups: comp.sys.apple2
Subject: Re: RamFast Write-Through Cache?
Message-ID: <1991Apr18.024453.2902@ims.alaska.edu>
Date: 18 Apr 91 02:44:53 GMT
References: <613@generic.UUCP> <1991Apr17.143801.22825@m.cs.uiuc.edu> <Apr.17.16.47.15.1991.9916@aramis.rutgers.edu>
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In article <Apr.17.16.47.15.1991.9916@aramis.rutgers.edu>, joseph@rutgers.rutgers.edu (Seymour Joseph) writes...
>In article <1991Apr17.143801.22825@m.cs.uiuc.edu> bazyar@ernie (Jawaid Bazyar)
>writes:
>>   The RAMfast cache is what is termed as "write-through", i.e. any data
>>written to the card is immediately written through to the disk. 
> 
> 
>Jawaid,
> 
>I own a RAMfast SCSI card, and your statement conflicts directly with my
>experience, and my discussions with CV Technologies.   When I write data to
>disk, there is often a delay between when the program starts writing data, and
>hard disk activity.    The cache on the Ramfast is not a write-through cache.  
>The card is Very fast so the delay is never more than a second or two, but it
>is there. 
> 
>Seymour

I also own a RamFAST/SCSI card alng with a ZIP/GSX1600 (not that it should
probably make any difference..).  I have noticed that there is
often a dealy when writing to the disk, but the delay does NOT tie 
up the computer.  Basically, as in example, you tell the compter to save
a file to the disk.  The computer (or so, the GS).  Now, Appleworks 
will say that the file is saved to disk, and it will let you continue
with whatever else you were doing.  Then, about a second later, the
info will be written to disk.  If you do a ProSEL backup (or a restore for 
that matter) then a group of data - several files, wil lall be written
to the disk at once.

Basically, as I understand it, this s one of the purposes of the RamFAST/SCSI
system.  IT is increadably neat, and very fast.  So, I have made a theory:

1)  The RamFAST/SCSI will write to the disk if it doesn't recieve any
    data to read from the computer for awhie.  e.g., you send the card
    a 20K file, and continue with your work.  It writes it when it wants
    to
2)  THe RamFAST will write to the computer when its RAM is full (256K).

My guess is that it uses both.  Either way - it is really worth the money!