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RE: Repeater and the CFC



Damon Langlois
Creative Director
Tel (250) 544-4091 Fax (250) 544-4100

-----Original Message-----
From: hutton [mailto:hutton@pathcom.com]
Sent: Monday, August 27, 2001 4:54 PM
To: Loopers-Delight@loopers-delight.com
Subject: Re: Repeater and the CFC

Want a laugh? ........ ask this man where you can purchase a 128mb
CFC in Canada ....... Listen to his company's  "Answer" ...... Note ,,,,, 
a Canadian company!

"Damon Langlois (Electrix)" wrote:

> >I saw your list of recommended CFC cards, included the SanDisk brand, 
> >didn't include the 64mb card. Would you recommend that card? I ask
> >there is a pretty good deal on these at my local Costco.
> It depends... The Sandisk cards work, they will record in stereo, and is
> very reliable cards. However the ones we tested did seem to have some
> speed limitations with Repeater. With the cards tested, I was only able 
> record in stereo for about 3.5 minutes before repeater reports "CFC Slow"
> and it stops recording (mono went for the entire 8 minutes with no
> problems). This only comes up when you have a 64 MB card or higher, OR if
> you are making extreeeeeeeeeeeemly long loops, OR if you are using
> as a digital hard disk recorder because you went out and bought a 512 MB
> card. Considering most loops are only seconds long it's probably only a
> minor limitation. The newer DaneElec and Simple tech cards seem to have 
> speed limitations with Repeater. Full stereo recording up to 8 minutes
> If you don't mind the minor speed limitations then you are probably o.k.
> will be very happy with the Sandisk card you are eyeballing. See if you
> arrange to try before you buy or get a return grantee and then you won't
> have to worry.
> The following was written to the list earlier by Don, one of the 
> at Electrix who sweated blood to bring Repeater to life.
> Disclaimers:
> ------------------------------------------------------------------------
> 1. The following is based on my experience and is my personal
>     opinion. It should not be taken to represent the official views
>     or position of Electrix/IVL Technologies. (even though the
>     conclusion is pretty much exactly the same).
> 2. The following only relates to CFC cards in the context of
>     their use with Repeater, and implies nothing about their
>     suitability or performance with ANY OTHER PRODUCT.
> 3. If you think I am being paranoid, I have been flamed badly
>     in the past. All this having been said, flame proof underpants
>     on and here goes...
> -----------------------------------------------------------------------
> I noticed the discussion starting around CFC buys. There is some
> stuff on the Electrix website, and also on a flyer shipped with the
> unit. However you do need to be aware of card specs - the only
> real way to know things are going to be cool is to test Repeater
> with the card you wish to use. Until specifications become a
> perfect art, rather than a marketting tool, that is just the way it
> is.
> Electrix has been doing a lot of testing with different CFC cards,
> and our recommendations are based on the results of those
> tests.
> Technobabble follows
> ---
> CFC card specs that are published from different manufacturers
> seem to cover the following:
> Burst-mode rate (quoted ~6-10MB/sec). Ignore this. Unfortunately
> everyone who designs a CFC interface needs to design for the
> lowest common denominator anyway, making this spec worse than
> useless IMHO.
> Read rate. Typically 800KB/sec -> 2MB/sec. Read rate is not
> really the issue. Reading flash memory is pretty damn quick and
> in Repeater accounts for a fairly small proportion of the time
> consumed at the CFC interface.
> Write rate. Quoted (ahem!) 500KB/sec -> 1.5MB/sec. However
> this is the long-term sustained rate, and depending on the card
> manufacturer, the data caching algorithms they use, and a whole
> load of other variables the short-term variance in write operation
> latency can be huge. I know - I have pored over the logic analyser
> and scope traces looking into this phenomenon until I went bug
> eyed [still in recovery...].
> CFC cards do some pretty nifty footwork under the hood to manage
> the storage medium - including error recovery, bad sector
> remapping, wear levelling etc... Also, writing is a cached
> mechanism and there are additional time effects due to the caching
> scheme used, the pattern of writes to the card and the amount of
> cache available.
> The result of all of this is that an apparently fast card may
> occasionally (or in the case of one card we tested, very often...)
> take a long time to complete a write operation. Hit a few of these
> long write operations in a row and all of a sudden Repeater will
> have run out of write buffer space and will inform you that there is
> an issue here...
> Most cards will handle the 'sequential' writing of mono operation
> with no problems. Stereo operation is where most problems lie.
> The pattern of writes to two .wav files can fight with the CFC
> caching scheme and cause the card performance to be somewhat
> less than desirable.
> So - that is the low down.
> ---
> My advice is to read the specs (the faster card manufacturers will
> quote them with pride. The slower card manufacturers will quote
> them under a subtle disguise to make you think they are better
> than they are...). Take all specs with a healthy dose of reserve.
> Then, if you can test a card before you buy, do. We are providing
> information on cards we have thoroughly tested and are happy with
> to help with purchase decisions.
> The Simple Technologies cards deliver. DaneElec also are just
> dandy. This does not imply that other cards out there will not
> also do just fine, but it provides a starting point. I hope that with
> experience that this forum will provide more information about
> good card choices for use with Repeater. We will also update
> the information on the web site as more experience and test
> results become available.
> Please consult the website and feel free to post questions
> for us folks about CFC cards. We will be happy to occasionally
> break the lurking mode and provide what information we can.
> Cheers, and I hope you folks have a *lot* of fun...
>         Don Goodeve
> (of Rik Elswit's 'Don and the Maniacs' fame... I kind of like that
> one...)
> ps. CFC technology is moving *damn* quick these days, and the
> speed of cards will become less of an issue as time goes on. With
> Repeater we had to design towards where we expected CFC
> technology to be, and fortunately our Crystal Ball did a pretty good
> job.
> Respect,
> Damon Langlois
> Creative Director
> Electrix
> Tel (250) 544-4091 Fax (250) 544-4100
> http://www.electrixpro.com