problems burning a blank 27c256!?

[unruhjonny]

Hello;

I was suggested to come here for the information I need.

I run a drivetrian that uses a 27c256 eprom.
I know of other people in my community who area able to successfully burn an erased 27c256.... I seem to be having issues.

Backround;

Currently using Moates Flash & Burn as well as TunerPro RT.
I have a Moates APU1 (all in one).
I use an HDR1 to read/capture stock bin files, and (at least in theory) burn to the erased (still assembled) GM memcal.
I have access to a chip eraser, and already have several cleared.

F&B says that the chip type 27c256 is "read only" - I had presumed that this simply meant that I could not electronnicly erase it (which I know isn't possible with this chip type btw).

I changed to another chip type (can't off hand recall which one it was), and changed the hex addresses to match the original parameters for the 27c256 (000000 & 007FFF?? or something)
I was able to burn - but upon reading the chip, it's quite obvious that it didn't work properly;
The speed limiter/fuel cut out was correct (but that mght have been by sheer chance because I maxed it out), but the rev limit and others were seriously bunked.

Does anyone have a go-around??

Mabey I need to select a specific chip type and change the hex addresses to something completely differentand to "fool" my APU1 into burning my chip(s) correctly??

BTW;
The guy who was supposed to be helping me out on this hasn't even had the courtesy to email me in several months (but he has been online!?)...
I guess good deeds do in fact go unpaid.
I've helped out this guy ALOT already, and he has financially benifited from my help.


Please someone chime in - I know that several 60degree V6 cars came with 27c256 chips (confirmed this on the tunercat site before comming here).

Jonathan

[SappySE107]

the flash and burn will not program a 27C chip. Read only. Get a 27SF512 chip and everything will be fine. The burn1 will automatically set it to burn on the second half of the chip for your 32k .bin file.

Its a voltage issue, so you aren't tricking anything to "get around" this. You could buy another burner but its far more complicated to go that route than to buy a chip that not only lasts many many times longer than a 27C256 chip, but it also requires no UV light to erase.

[unruhjonny]

well thanks for the advice.

I am don't know if I can adequatly convey just how uninterested I am in removing the chip... what burners will work.

I bought hte APU1 because I had understood that it would work for me.
There are alot of GM cars that use the 27c256 chip... this is a smidge disappointing.

[SappySE107]

Get an adapter. No one said anything about desoldering a chip from the memcal to do this. The 27C256 chip hasn't been used by GM since 1995 and the 29C256 chip that most of us used instead is no longer made either.

At best, you will get 4 reflashes on a stock GM 27C256 chip. I know because I used to use those and I still have the UV eraser. Unless you plan to burn once and be done, its not worth the effort. Even then, the new flash chip with adapter is a piece of cake and you have the stock chip still intact.

[unruhjonny]

thanks, that's what I'll do for time being.

I have access to a UV eraser, but would be nterested in buying my own... if you have hardware you were previously using for burning the 27c chip and you would be interested in "unloading" it... message me(!)

The AUP1 (not to be confused with the BURN1) came with a single 27sf512, and I already had an adapter (came with a jet chip I pulled out of a GTZ!)... so this will be what I'll do for now...
eventually Iwould really like to be able to simply flash & reburn to the original chips (if I can find enough that are erasable (I had no idea just how common the 27c256 non-erasable version was!)

Thank you very much for your help.
I found absolutly no resourse that simply stated that the 27sf512 was supposed to be used in place of the 27c256.

Can you do me one more favor?

chip addressing:
according to F&B the start & end for the 27sf512 is 008000 & 00ffff; but how do I know the buffering address will be correct?
Does the buffer address get set by the bin file that I load to the program? - or do I need to manually change it?
FYI: My 27c256 uses 000000 & 007fff as start & end.

[Guest]

The adaptor is easy to use and will allow full functionality of your APU1 for emulation.

The G1 is the adaptor you need. http://www.moates.net/product_info.p...products_id=32

For easier use get a ZIF socket. http://www.moates.net/product_info.p...products_id=44

Use SST 27SF512. http://www.moates.net/product_info.p...products_id=39

You can also get it all in one package with two EEPROMs. http://www.moates.net/product_info.p...products_id=41

For a programmer that will program the 27C256, go to MCUmall.com. I use a Willems "true usb" GQ-3X, Very easy to use, and will program other types of chips as well, if you get into other forms of electronic prototyping. If not, it's overkill, especially since the 27C256 EPROMs fail quickly and often.
I also have a Willems "dual power" programmer that is more involved to use, since there are dip switches and jumpers that need to be set and changed between reading and programming EEPROMs, and also when a different chip is read or programmed. I keep it simply as an emergency back-up if I have any problems with the GQ-3X.

[unruhjonny]

thank you again for helping me out with info here, I truly appreciate it - untill you spoke up, I had simply hit a brick wall.

my jet chips adapter is exactly the same as the 'G1';
I had an SST-27SF512 included with my APU1

Thanks for pointing out that chip link - I may have read this before, but now it takes on all new meaning;
"For 27C256 original, set to 8000 hex"
Does this maybe mean that the 08000 & 00FFFF are correct addresses?

incase you didn't notice this is what I bought - it shows what was all included: APU1

Other than reading description like the SST one you gave me - is there a quick guide for interchangeability of chips, and hex address changes to accomidate for each chip type?

I'll look into the burner(s) you mentioned!

[Guest]

Since you have the Jet Chip adaptor, you don't need to worry about buying any other programmer, it sounds like you have everything you need.

Forget trying to program the original EPROMS, they are flakey at best.

Use you adaptor and the inclused 27SF512 EEPROM.

Yes, moates has information on what offsets to use with different bin file sizes on different E/EPROMs. It listed under the documentation link on the home page.

[unruhjonny]

Ok - thanks again, you've been a huge help!