27C128's are getting few and far between (as far as the places I'm looking for) besides the fact that most sites I've found are saying that it's obsolete. Is there any way I can use a 27C256 or 512 and only write to the upper portion, I realize it wouldn't read any information beyond 128k and wouldn't need to, but I thought maybe if I wrote the 128 at the beginning of the chip it may be able to read it correctly. Any help would be much appreciated. Thanks.

 

You could use a 27c256, but when a 29c256 flash works just as well, why not use that, assuming you have a programmer that will do flash chips.

That's what several of us are using and it's much faster and easier than using uv-erasable proms.

 

27128A will work also.

------------------
1982 Z-28

See http://www.mycar.net/mafb/registry/detail.cfm?id=276 for details

 

I haven't purchased a programmer yet due to that reason, I'm not sure what to do yet... Will that work with the original ECM and everything? Thanks for your help!

 

Uh...that's what I meant when I said "27128A will work" above.

Pretty sure that's what afgun meant when he said "29c256 flash works just as well" also.

------------------
1982 Z-28

See http://www.mycar.net/mafb/registry/detail.cfm?id=276 for details

 

...If the "and everything" includes desoldering the OEM EPROM and installing a ZIF socket, then why heavens sake YES!!!

Do yourself a favor and get the 29C256's; forget the UV Eraser; and buy a Flash programmer (I use the Pocket Programmer)...

 

Absolutely. As you mention, you don't need a UV Eraser, but also the Flash Prom is only a $1.00 more than an eprom and lasts virtually indefinitely instead of 25-50 reburns, like the eprom.

Also, the Flash Prom reprograms in seconds instead of waiting for the UV to erase the eprom, which slowly takes longer and longer. By the time I get to my 25-30th burn on an eprom, I was waiting almost an hour for it to erase. Not very good if you want to make a couple of quick changes and retest.

 

One last question... Are the memcals from a 305 and 350 the same? If so I can start the show but I have a memcal from a 305 (swapping to a 383). The 350 stuff still won't be great for a 383, but hey, isn't that why I'm at the DIY Prom section?

 

You SHOULD have a memcal as close to your set up in case you ever go into "Limp Mode". In "Limp Mode" the engine relies on your Memcal circuitry rather than the eprom itself. There isn't a Memcal for a 383, so the closest is the 350.

Without it, you may find that if you ever do go into "Limp Mode" that you may not be able to even fire your up engine so you can pull over to the side of the road.

 

I seem to recall reading here that someone had hacked the Limp-Home MemCal chip from a V-6 to work with 8 cyls...Just for emergencies...

Just for giggles, I re-Flashed an I-4 MemCal and tried it in my L98. The MemCal itself worked OK; the Flash was successful...But woe unto me if I ever *needed* the Limp-Home mode...

 

Cool thanks a lot for the info, I have a memcal that came from a hypertech replacement that is for a 350 so I'll just use it instead of the 305 one. That's why I bought the chip in the first place, so that might be able to run the 383 with it, kinda glad I did now

 

so the pocket programmer can also do flash eproms. are they just the same as the regular eproms just dont need to be erased. so the only advantage is that they are quicker to erase and burn. but everything else is the same. if so what is the flash eprom id need for an 89RS TBI. i think i need a 27c128 eprom.

 

No, your car uses 2732s and there is no Flash Prom equivalent.

Now, if you were to get "deeply involved" into the "Source Code" and try making a "ROM Less" ECM and moving that info to the eprom, you might be able to convert you ECM to handle a 27C128 (at which point you could use a Flash Prom).

I know someone that has done that with another vehicle that uses the 2732s (not a TBI car though). Maybe he'll respond and indicate what you need to do...but let me warn you - it's very advanced information and "not for newbies".

 

ok thanks, i realized later that i was looking at the 89 TPI chart and not the TBI. i do need the 2732's. do u know where i can get some for cheap.

 

No I don't unfortunately. But this question gets asked all the time. I suggest doing a search on "2732" on this board and reading some of the recent posts.

 

If the pinouts were rearranged, I wonder if a 2732-bearing ECM could be made to read off of a flashed 29C256, assuming that all the memory allocation was done properly...

Any thoughts? Maybe the memory segmenting would not allow this...