RE: Intel sez: Synchronous Flash and XIP is the future -- thought s?

RE: Intel sez: Synchronous Flash and XIP is the future -- thought s?

[Paul Nash]

So what are people out there using in their designs for NAND primarily?  Raw
NAND?  NAND plus some bootable sector?  DiskOnChip?

-----Original Message-----
From: Charles Manning [mailto:manningc2@actrix.gen.nz] 
Sent: Monday, December 16, 2002 3:19 PM
To: Russ Dill; linux-mtd@lists.infradead.org
Subject: Re: Intel sez: Synchronous Flash and XIP is the future -- thoughts?


On Tue, 17 Dec 2002 10:21, you wrote:
> On Mon, 2002-12-16 at 14:02, Charles Manning wrote:
> > Intel's flash is expensive. Figure somwhere over $1 per MB.  NAND 
> > costs approx 30c/MB + SDRAM approx 20c/MB.  Intel's flash thus costs 
> > approx twice what a NAND/RAM image does.
> >
> > One NAND flash footprint can give you up to 256MB of storage.
> >
> > NOR fully sucks for any sort of writeable file system performance. 
> > NAND runs a very usable fs with YAFFS or JFFS2.
> >
> > The only benefit I can see in NOR is a faster boot. This is becoming 
> > less of an issue as more designs switch to sleep/resume models.
>
> It really depends on how much data you store, and how you use that 
> data. Sure, for you, with a dynamic file system, and 256M of storage, 
> NAND is an easy choice. But many designs out there have static file 
> systems, use 2M or 4M of flash, and for such designs, NOR offers a lot 
> more simplicity for around the same cost as a NAND + boot logic. With 
> NOR flash, I can put a couple cramfs filesystems on there, and use the 
> boot block for storing a simple journalled config, reliably. I don't 
> have to worry about setting aside blocks in case one goes bad.
>
> I think this is the market intel is targeting, just change 2M or 4M to 
> 4M or 8M (no more compressed fs).

True, flexibility is the key. If 2-4MB with a static fs is all you need,
then 
no need to take on all the extra drama.

However, to get back to the start of this thread, Intels big push is for the

larger sizes (8MB+) where NOR is less palatable.

-- CHarles

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Re: Intel sez: Synchronous Flash and XIP is the future -- thought s? -->NAND

[Charles Manning]

On Thu, 19 Dec 2002 02:13, Paul Nash wrote:
> So what are people out there using in their designs for NAND primarily? 
> Raw NAND?  NAND plus some bootable sector?  DiskOnChip?
>

NAND has been around for over ten years now, but the real uptake has only 
been very recent.

Until recently, most people have used DiskOnChip which is essentially just a 
raw NAND + an ASIC to do ECC + a very expensive price tag.

Probably most NAND in use is SmartMedia (numerically speaking) - using FAT. 
These are just raw nand on a carrier card. Just ask David Woodhouse what he 
thinks about that! THis is being superceded by XD card. 

Now that there are very reliable NAND file systems (JFFS2 and YAFFS) that run 
under Linux and other OSs, it is becoming increasingly palatable to use raw 
NAND parts soldered down, or use SmartMedia/XD if you want an expanadable 
system.

The new generation NAND parts expand to 16-bit data buses and have bootable 
code space. This makes it possible to build systems that are all NAND with no 
NOR in sight.

-- CHarles