ASMN is 01 code mask?!

[SappySE107]

I am trying to make a performance chip for an 87 2.8 3 speed J body, which uses ASMN. The copy I have is 01 code mask...no idea what that is.

ASMN.BIN

The car has a digital dash, so I have to use a chip that is going to keep that functioning. I was hoping to find a 6D mask chip that would eliminate the MAF but I have nothing on my superseded list.

[neophile_17]

I don't recall if it had a digital dash but I got my ECM from an 87 A-body. It uses ASMT and the copy of ASMT I got from Robert's website is 6D. I do remember the sticker indicating the MAF was disabled. Let me know if you want me to check something out.

~sam

[SappySE107]

ASMT might work but I am not sure if the speedo code is the same. Both are 3 speeds but the FDR isn't the same. MD9 vs F17 and F75.

[robertisaar]

looks like a bad read to me...

vectors that are present starting at FFEE are also copied to FFAE, kind of acting like a worn out burner.

that and the reset vector points to A000(standard location), which isn't possible with a 16KB BIN.

try reading it as a 32KB file Ben.

[SappySE107]

wasn't my read Figured it was a POS...that sucks.

[robertisaar]

too bad....

it is a 6D BIN though, well, a non-borked one would be anyways.

i threw in 16KB of nothing in front of the BIN to expand it up to 32KB, then did a compare to a similar 6D BIN and saw some interesting patterns...

every xx80(A080, A180, A280, etc) address line, what would be algorithm, it gets all messed up until xxBF, and then goes back to normal.

it repeats like that through what's left of the BIN, so somebody's programmer was WAY messed up when it was read, or the PROM itself was crap to begin with AND it was read wrong.

[Superdave]

The last few i've sold for 87 Jbody 3400 swaps were all $A1 BFUZ with the correct VSS settings.. no complaints.

[SappySE107]

Digital dash does not work with A1 or I would be doing that as well.

[robertisaar]

is it just the speedo that doesn't work, or the entire dash?

i'm looking over the schematics for a 87 cavalier 2.8 and i'm seeing a VSS connected directly to the dash. i assume the cluter does some type of dividing or otherwise conditioning of the signal, since it is then branched off into 2 other circuits, 1 for cruise, the other for the ECM(pin C6, which i have listed as VSS optical input).

i did find some interesting things during my disassembling of 6D/88 that may allow the use of an optical VSS with A1, i just need someone(preferably with a bench or factory equipped car) to beta-test it, since i don't have any clusters that use an optical unit.

[SappySE107]

I think it was just the speedo that didn't work, but I haven't tried a digital dash with A1 in years.

[Superdave]

I've got about 10-15 $A1 chips out there with digital dashes, the 87 iirc i use 4000ppm since the dash feeds it, same with 88..


Robert, i think we were talking about that a while back when i was trying to get the optical output from my 89 Camaro to work with $A1.. i finally just got a dual out VSS and ran it to the standard inputs.

[robertisaar]

i remember the issue Dave, and it still bugs me, which is why i want to get the optical stuff figured out.

from the looks of it, a single bit controls using the magnetic input or optical input, though GM never mentions it in the callout document. probably since by the time A1 came out, nothing used optical anymore.

[SappySE107]

I ended up having ARDC, which is 1988 3 speed auto J body. Same speedo code as ATZA, which is the 5 speed 87 J body. I am hoping this will have the same speedo code as ASMN.

[andrewz24]

ASMN $6D.BIN

Here is a good copy of the code.

Andrew