Would it be possible to write a 27c256 chip for use as a 27c128 chip? Is there anything different that i should be aware of when writing? or will writing the chip and having half of it blank aposed to it being full if it were a 27c128 be a problem?

Brendan

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1987 IROC-Z L98,SuperRam,EB 6085's,LPE 219/219 Roller, Crane 1.6RR, EB TPI Base, 58mm TB, ADS 24#, AFPR, K&N, EB TES, Catco Cat, 3" Borla Cat-Back, Accel cap,rotor,distro/other crap, MSD 6AL, MSD Blaster 3, Aluminum DS, 94 Disk Rear, Adjustable Valve, Precision 3.73 Gears, Sub-Frame Connectors, Hotchkis Lower Control Arms, KYB Shocks/Struts, Suspension Techniques Lowering Springs, Polyurethan Bushings all over the place, Moog Upper/Lower Ball joints and Tie Rods ends/Idler Arm,

To see the ROC, Check out the webpage Here

 

Brendan,

Yes, you can use a 256 chip in a 128 application. HOWEVER, you must load the image into BOTH halves of the EPROM. If you do a standard program then you will only be programming half of the EPROM ... that is not a problem as long as you program the correct 'half'. To be safe - program the double size EPROM with the same image twice. Make sure you change the start address on your programmer for your second pass.

Tim

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TRAXION's 1990 IROC-Z
Best Time = 12.244 @ 112.51mph (1.778 60' / 7.819@88.32mph in the 1/8)
All Natural. No Force. No Drugs. Stock Bottom End. Stock Body Panels.
Gunning for NA 11's with bigger cam, bigger stall, and bigger exhaust.
-=ICON Motorsports=-
Moderator: PROM board at thirdgen.org

 

Tim,
Thanks, i wasn't to sure. That answers tons of questions. I'll do that tonight. Thanks for the help. I should be able to get that to work. This question pretains to my other posts. If you could look at those that would be cool.

Thanks again,

Brendan

 

Oh yes, i forgot to ask, what hex address should i start programming at for the second half? 07FFF?

 

Brendan,

I did read your other posts almost directly after you posted them. Truth is - I am not sure what is going on with your programming. It almost sounds like you are having a problem with the PP ... or it is not set up correctly. Very wierd.

The start address is the next address after 7FFF. That would be 8000 (if my math is correct)

Tim

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TRAXION's 1990 IROC-Z
Best Time = 12.244 @ 112.51mph (1.778 60' / 7.819@88.32mph in the 1/8)
All Natural. No Force. No Drugs. Stock Bottom End. Stock Body Panels.
Gunning for NA 11's with bigger cam, bigger stall, and bigger exhaust.
-=ICON Motorsports=-
Moderator: PROM board at thirdgen.org

 

Tim,
I'm going to try and write onto that 89memcal that has the factory soldered 256chip in it. With the technique you suggested. Upon further investigation, a friend found that one of the pins on my ZIF socket was a little "iffy". It would make connection but if pressure was appliedit would loose connection so we got that fixed and now my stock 89 apyp vette chip gets me to the diagnostic mode, but the car started with it!... i thought it was sposed to have vats enabled? another weird thing is that the service light was on while the car was running with the stock vette chip. Thats alittle puzzling.

 

Brendan;

I am pretty sure that the 89 calibration units are 27128's - 128K EPROMS only. I don't think that there were any 256K ones.
Are you sure that you are using the right
cal unit - what's the part number / bin code on it? This could be the cause of your problems...

Do the 90 - 92 SD cal units look the same as the 85-89 165's? I never saw an SD memcal...



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89 Firebird Formula
WS6 package,ZZ4 Crate engine
SLP 58MM TB, Edelbrock TES Headers
Random Tech 3" cat, SLP 3" stainless exhaust
9 bolt rear, Hotchiss swing arms, Lakewood panhard rod
Corvette 2/4 servo, kevlar band, full poly rear.
Centerline 16x8 rims, B.F Goodrich drag radials

 

Sometimes GM used a 256 in place of a 128. Not all chips that are suppose to be 128 actually ARE 128 from GM. Many were found to be 256.

Tim

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TRAXION's 1990 IROC-Z
Best Time = 12.244 @ 112.51mph (1.778 60' / 7.819@88.32mph in the 1/8)
All Natural. No Force. No Drugs. Stock Bottom End. Stock Body Panels.
Gunning for NA 11's with bigger cam, bigger stall, and bigger exhaust.
-=ICON Motorsports=-
Moderator: PROM board at thirdgen.org

 

I'm sure the memcal is from an 89. When i hooked the memcal up and let it go in diagnostic mode, i got a code 46(vats problem). So i'm sure its an 89. I bought a spare computer for cheap(40bucks!). The guy let me have the memcal also!, so luckily i got a great deal and an extra computer or memcal , however you want to look at it.
The delco chip says 27c256. I was very suprised myself. I'm at home now and am going to be writing to both halfs of the chip to see what it does!.

Brendan

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1987 IROC-Z L98,SuperRam,EB 6085's,LPE 219/219 Roller, Crane 1.6RR, EB TPI Base, 58mm TB, ADS 24#, AFPR, K&N, EB TES, Catco Cat, 3" Borla Cat-Back, Accel cap,rotor,distro/other crap, MSD 6AL, MSD Blaster 3, Aluminum DS, 94 Disk Rear, Adjustable Valve, Precision 3.73 Gears, Sub-Frame Connectors, Hotchkis Lower Control Arms, KYB Shocks/Struts, Suspension Techniques Lowering Springs, Polyurethan Bushings all over the place, Moog Upper/Lower Ball joints and Tie Rods ends/Idler Arm,

To see the ROC, Check out the webpage Here

 

That is good info to have. Now if we can just find a way to switch between those different bins whenever we want. I have been digging around for info and from what i hear, it should be possible to make a swith to select which bin we want to run without even having to turn the car off.
Anyone know how to do that?

 

Bonestock,

Dude - that info is closer than you realize. Just search this messageboard and you'll find that info. Tim Burgess posted that info about a couple weeks after we opened the board.

Tim

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TRAXION's 1990 IROC-Z
Best Time = 12.244 @ 112.51mph (1.778 60' / 7.819@88.32mph in the 1/8)
All Natural. No Force. No Drugs. Stock Bottom End. Stock Body Panels.
Gunning for NA 11's with bigger cam, bigger stall, and bigger exhaust.
-=ICON Motorsports=-
Moderator: PROM board at thirdgen.org

 

Tim,
I think i stumbled across the problem with my 128 chips. Turns out that a flacky pin is not quite making the best of connections. After some trial and error and a couple more hours of testing. I was able to get the APYP no VATS chip to successfully run on the car. And let me tell you, it ran like a beast!
I have a lot of back firing but that is from the timing being WAY off.. switched distributors out and haven't gotten the timing set yet due to trying to get the prom worked out.

Oh and i tried to write on both "halves" of that 256 chip. That didn't seem to go very well. When blank checking it, it only came back with 007F00 as the last address. I could write to half of the chip and the other half would error on different addresses. I tried erasing the chip about 5-6 different times, 10-30min each time. I'm not going to worry about the chip too much now that i have a working prom now.

Thanks Tim, and everybody else for the ideas/suggestions,

Brendan