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Orangetona
03-05-2007, 10:36 PM
Hey guys, I did some searching but I dont know which eeprom I need for my car. Its an 89 SMEC 2.5 electronics. If you can give me a part number for a compatable one that would be great. If you need anymore info, just ask.

Orangetona
03-05-2007, 10:43 PM
Searched a little more, is it, 28c256?

ShelbyMotorsports
03-06-2007, 12:26 PM
Searched a little more, is it, 28c256?


It's actually 27c256 but they are getting hard to find. I don't think 28c256 is a replacement for it so better double check before buying those.

Steve

ShelGame
03-06-2007, 02:08 PM
The 27C256 is a UV-EPROM, not an E-EPROM (ultraviolet vs. electrically eraseable). The 27C256 are all over the place. You can get them on eBay for less than $1/ea in quantity.

The 28c256 is used in some of the flashable conversions, but it's not pin-compatible. It requires some modifications to the SMEC to make it flashable.

The 29C256 is a pin-compatible 28-pin DIP EEPOM, but it's discontinued. You may still be able to get some on eBay or on Moates.net.

The 27SF512 is a pin compatible flash PROM, but it's a 64k chip instead of 32k, so it will need an appropriate offset when a 32k cal is burned to it.

ShelbyMotorsports
03-06-2007, 03:00 PM
The 27C256 is a UV-EPROM, not an E-EPROM (ultraviolet vs. electrically eraseable). The 27C256 are all over the place. You can get them on eBay for less than $1/ea in quantity.



Not all 27c256 are UV proms as the ones I use are not UV.

I have to also disagree that they are all over the place. Sure you may be able to find USED UV proms on ebay but that is not what I posted about.

If you can find me brand new 27c256 non-uv chips for $1 I'll pay you a finders fee.

Steve

ShelGame
03-06-2007, 04:03 PM
Not all 27c256 are UV proms as the ones I use are not UV.

I have to also disagree that they are all over the place. Sure you may be able to find USED UV proms on ebay but that is not what I posted about.

If you can find me brand new 27c256 non-uv chips for $1 I'll pay you a finders fee.

Steve

The 27c256 is either a UV or an OTP. I don't know of a 27c256 flash or EEPROM.

The 29c256 is a pin-compatible flash EEPROM that is obsolete and very hard to find. The do pop up on eBay from time to time for ~$10/ea.

Here's Mouser.com's page for the 27c256. They stock many versions of the 27c256 in CDIP (UV-Eraseable) and PDIP (OTP) packages. The CDIP's as low as $2.09, the PDIP's for less than $2.

http://www.mouser.com/search/Refine.aspx?Ntt=27c256&Ns=P_SField|0

Here's the page on DigiKey.com :http://www.digikey.com/scripts/DkSearch/dksus.dll?Selection

On DigiKey, you can get them for $0.75/ea if you want to buy a lot of them.

They're by no means obsolete or hard to find.

I have bought them on eBay for less than $1/ea brand new. Although, there are none up there now.

mock_glh
03-06-2007, 04:21 PM
I use at29c256 chips for my LM and SMEC cals. They are awesome! You can get them here:
http://www.americanmicrosemi.com/products/search/
Get the ones that are $3.29, they work fine. I use the Willem "Enhanced" programmer with the 97g software.

ShelbyMotorsports
03-06-2007, 04:31 PM
The 27c256 is either a UV or an OTP. I don't know of a 27c256 flash or EEPROM.



You are correct. The ones I use are the OTP. I only went by the OP's part number and now see that what he really wants is an EEPROM.

Oragetona, Boyd posted the part # that a lot of us also use.

ShelGame
03-06-2007, 05:09 PM
I use at29c256 chips for my LM and SMEC cals. They are awesome! You can get them here:
http://www.americanmicrosemi.com/products/search/
Get the ones that are $3.29, they work fine. I use the Willem "Enhanced" programmer with the 97g software.


Wow, that's a great link - and price. Thanks!:thumb:

iangoround
03-06-2007, 11:10 PM
what is the proper offset when using the 27c512? I heard to use c000 for LMs, is it the same for SMEC? Are they both 32k files or is the LM only 16?

cordes
03-06-2007, 11:48 PM
what is the proper offset when using the 27c512? I heard to use c000 for LMs, is it the same for SMEC? Are they both 32k files or is the LM only 16?

Lm is 16 SMEC and SBEC are 32. Actually I guess I should say that the 87 TII cars are 16K as the GLHS and earlier TI cars are 8K on the top chip, and 8K on the bottom chip.

ETA: I forget the offset on those, but I believe it is listed on moates and also on moparchem.com

iangoround
03-07-2007, 12:51 PM
I'll dig around a little more for that info then.

So 87TII cars have a single 16k chip and the TI cars use two seperate 8ks? Is one an "operating system" and the other "application"?

cordes
03-07-2007, 12:58 PM
I'll dig around a little more for that info then.

So 87TII cars have a single 16k chip and the TI cars use two seperate 8ks? Is one an "operating system" and the other "application"?

Honestly, I don't really know exactly how the earlier LM and GLHS chips are broken down. I have seen a socketed GLHS Lm that someone posted pics of, and he was only swapping out the top chip, so I would assume that is where the table files necessary for moding fuel spark etc. are, but I am not to up on it.

iangoround
03-07-2007, 10:09 PM
are the 87 t1's like that too or no?

cordes
03-08-2007, 12:02 AM
are the 87 t1's like that too or no?

From what I have read sometime in 86' the switched over so that the TI LMs had the ability to control everything just like the TIIs, so I think it is safe to say that all 87' TI LMs can be socketed and a cal made just like the TII LMs from the same erra.