AND Flash

[Charles Manning]

> Does anyone have experience with AND flash? Does MTD support it?

You're looking at the Hitachi stuff right?

I have not used it, but I have had a good sniff around it when evaluating it 
as a storage option against various others. NAND won in the end for the 
following reasons:
* Simpler interface. The AND chips required some funky extra clocks.
* Cost: NAND prices started to fall rapidly. I believe they are now cheaper.
* Multi-source: As far as I can tell only Hitachi does AND. ie. supply 
concerns.
* Supply concerns: AND uptake by the market is uncertain, leading to future 
availability concerns.

Functionally AND is much the same as NAND. ie. page/block oriented stuff.

At the start of the investigation, AND had appeal because it was the cheapest 
per bit. Since then however, NAND (Samsung/Toshiba) prices have fallen 
dramatically and densities are increasing. This, I attribute largely to 
Smartmedia uptake. As NAND rides the Smartmedia consumer wave, I expect to 
see further price drops and density increases. Unless AND gets a similar 
boost I expect it to fade away.

Without having investigated things too far, I'd expect AND to be able to slot 
into mtd rather neatly as a NAND variant. AND commands are likely not the 
same, but equivalent ones exist.

IMHO


-- Charles