when searching Pioneer-Stardard's page, there are many different types of these EEPROMS. I ordered 2 x AT29C256-12JC, and when they showed up, they were the wrong ones!! I shoulda read the board more carefully to make sure I had ordered the right ones. These are surface mount, and there's no way in hell I'll get them to fit in my computer.... there's 20 bucks down the bowl...

 

Yes the "PC" is 28 pin DIP and will fit the memcal. Mike

 

The "P" designation is the 'PDIP' 28-pin designation, and the "C" is for commercial applications. If it had a "PI", it would be a 28-pin designated for 'industrial' application. The "I" chips have somewhat more tolerant ratings for temperature, etc.
FWIW...

 

Usually on automotive electronics you want to at least go with Industrial temp. chips. Commercial versions will work most of the time but are not really designed for automotive environments. Depends on the weather where you live.
Industrial: -40 F to +185 F
Commercial: +32 F to +158 F

J

 

Commercial only down to +32? Huh... Oh well, I'm in Lousyana. Shouldn't be a problem.

 

Yeah, check out the datasheet at Atmel's website.
Commercial is spec'ed from 0 to 70 Celcius. That is the standard for only commercial device. Oh, I converted to Farenheit ( approx. C*1.8+32).
Where I live I run all Industrial stuff for reliability.

J

 

I've been using the "Commercial Grade" for well over a year and it has operated from 0*F - 100+*F.

Remember, that it will only be that cold when you first start your engine. Also, on a few Memcals that I've scoped out, they too use "Commercial Grade".

But if you can get "Industrial" at the same or nearly the same price...go for it. Also, while it is nice to have "fast" speed eeproms, your really don't need anything too fast. The ECM is far slower than the speed of even the slowest AT29C256 that I've seen.

 

Most things in this world are designed / speced with a safety margin. If you rev you engine past the factory set revline....will it stop working or is it no big deal? Some engines stop working and some don't.
The temp. rating of a device has a lot to do with it's guaranteed speed ratings. The late 80's and early 90's ECM operate these chips far below the manufacturer's ratings at temp.
If a person lives in a an area where it gets cold and wants the added insurance that the chip will function as designed (run the engine) they should probably go with Industrial grade devices. Why cheap out on a $10 item that is crucial to the engine operating, anyway?
J