Does anybody know what programming language GM used for the p4 ecms? From what I understand, people don't write software in machine code. It's usually done with a higher level programming and converted to machine code for the MCU.

 

Assembly.

RBob.

 

I have to agree with RBob. All of the assembly I have seen from compilers looks very different than what an ECM assembly looks like.
Remember, you are reading 80's and early 90's code that is based on the original 80's code. Back then an Intel x286 was "fast" there wasn't a lot of "good" compilers. Kids played on VIC20s. To have an engine running off a computer was a real accomplishment. Windows wasn't even around. Bill was still sucking money from IBM to create his fortune.

Yes, looks to be done in assembly.

J

 

makes sense.

on a sidenote, do you guys think it's possible to program the (p4)ecm in a higher language and compile that to work? It seems like it would take forever to do with assembly, by myself. I'm still learning how to understand assembly. So this is a long term goal, to run my own code from scratch. Trying to think of ways to cut time. From what I understand, one could write a single line of code in a higher language and that would be like multiple lines in assembly.




One last question, how hard would it be to use a personal computer to replace an ECM/PCM? There must be a way to at least use GM code and emulate the hardware. Might have to use dos...what about storing the code within the bios? Might have to make a I/O board or something though.
This seems like the "ultimate goal" considering p4 ecms are not going to be made forever. It's something I have thought about recently...

 

you can program any MODERN PCM in C....

and no, you cant emulate a ECM with a PC and have it actually run a engine... atleast not without making custom hardware... you can somewhat emulate it in the PC though... and emulate the engine..

 

That is why I mentioned an I/O converter, or something....

 

It's definitely possible. The two things you would be fighting (and have to keep an eye on) are total code space (ROM) and execution time. I know newer compilers can do a pretty good job of optimizing so that you don't always generate 100 lines of assembly for each line of "C". I wonder how many "mature" HC11 compatible compilers are that well optimized.....?

 

Do a search for a post where Funstick was going to re-write the assembly in C in about a month or two. He said that in February but has not provided any updates since then.
Ask him if it is ready. It might save you a lot of work.

J

 

Interesting tidbit: I've heard something about GM now using Modula for their current vehicles.

 

The subject was beat to death at DIY-EFI years ago.

Reprogramming in a different language. Why?, what's wrong with what's there?. Why not learn enough to just comment out, and streamline what already works.