29C256 Flash works great!

[Shawn R. Lin]

WEG1192 at aol.com wrote:
> 
> How does this differ from a ROM emulator? If I understand this flash device,
> you still have to pull the chip, and fast erase/reprogram without the 15
> minute EPROM erase step?

John,
The flash chip is very different from a ROM emulator:
1) The flash chip is nonvolatile - remove power from it, and the
contents are still there.
2) It cannot be updated or changed "on the fly".

Also since the P4 ECM's don't support writing to flash chips, the chip
also cannot be programmed in the car.  I suppose a very enterprising
individual could probably connect the /WE (Write Enable) pin to
something in the ECM and write a program that allows updates through the
ALDL though.

So yes, you are absolutely correct that you do still have to pull the
chip, but it can fast erase/reprogram without the 15 minute EPROM erase
step.  I believe erasing is probably nearly instantaneous taking only a
few milliseconds.  I think it also programs a LOT faster compared to an
EPROM.  I can't remember how long it takes to program an EPROM, but this
flash chip was completely programmed as soon as I pressed the ENTER key
(1 second or faster).  Probably worth the $4, IMO!

Shawn



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