Intel sez: Synchronous Flash and XIP is the future -- thoughts?
manningc2 at actrix.gen.nz
Mon Dec 16 16:02:02 EST 2002
Ooooh flash, my favourite subject.
Yup, our Intel reps also put the hard sell on us too... Remember, Intel own
NOR flash and are losing market share as more people switch to NAND. Already,
most new WinCE devices are using NAND instead - at least for the bulk of
In general, NOR flash is expensive, slow and not very dense.
Because it is slow, you typically need to copy the image into RAM to get
performance. This does not apply to synchronous flash which provides better
If you're going XIP and want performance, then you need a full bus-width of
flash. The dollars and the board space start to stack up.
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.
Now that the newer NAND devices support limited direct execution of code
we're going to see the emergence of devices that have no NOR at all.
IMHO, XIP is the past, not the future.
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