After reading several of Grumpy's comments, I am finally convinced that I need to completely study and understand the source code running on my 7747. I found this statement on DIY-EFI "The '747 ECM uses a GM specific derivative of the Motorola 6809". What exactly is this "GM derivative" and where can I go to read about the assembly language used for this processor? I need some documentation that even a newb like myself can read.

Also, I'm very interested in eliminating the ROM code and running everything from the EPROM. I know that I will need to remove some things if I intend to retain my 2732 EPROM. The problem I have is that I don't believe that the hac I found contains the ROM code. Anyone willing to give me some pointers here?

 

Look on the Motorola site for the 68HC11 manual. It keeps moving around so I can't give you a direct link. Appendix A has a chapter on the instruction set. The '7747 processor has a subset of that set. Can use the hac to see which instructions are valid.

The ASDZ hac contains both the EPROM & ROM code. It is 12KB is size, 4KB in PROM, 8KB in ROM. Only area in teh hac tha tis gooofy is the crossover point of $DFFF to $E000, the instructions are incorrect. Don't need to remove anything from the ECM, just ground a pin and the ROM is disabled.

RBob.

 

Thank you very much RBob. The ASDZ hac that I have is in PDF format. When I save it in TXT format, the file is still quite large. Is this because it has not been "assembled" yet? Also, would you care to explain "just ground a pin" a little further or pass along a link that explains this?

 

<Homer>
Ahhhh, Source code.
</Homer>

I'd tell what today's project was involving source code but then I'd have to shoot you.

Suffice to say, the MAT has become an extremely important sensor on my car.

 

well... OK, but it better be good!

 

I hate that secret squirrel kind of crap! C'mon, Grumpy...cue us in...maybe even an appetizer of sorts.

 

I would love to have a clue as to what he's workin on, but I totally understand, and respect the reasoning for not letting stuff out into the wild.

 

Anyone else care to comment on this?

 

There's a basic flaw in most of the management systems, IMO.
But, as long as your running the stock code, there's just not much you can do about it.

I've harped and harped about a source code project, and everyone has gone off in different directions, so nothing's happened. Or on the one minor effort they've picked the wrong code to even begin with. So as long as no one's really going to try and work out a community Source code project, then things will stay statis quo.

While having a hac is wonderful, having source code is incredible.
I'll admit, I'm kind of at the extreme for what I consider right, but it's just because, I've seen what correct is. It's really a shame that in the last 4 years things have stalled here. yes, the words out that the oem ecms are neat, and there's alot more activity, but there's room for more workers.

 

It's not uncommon to have Source code that's 600K, to assemble into code for a 27128 sized prom. The size of the source code includes all the english comments, that aren't used in the .bin..

 

Ok, that makes sense. I'm also curious about that "ground a pin" comment. Do any of you know the specifics behind this?

 

I believe (if I'm not mistaken, RBob, Grumpy, feel free to correct me) that you can pull all the address lines and data lines right off the 40-pin edge connector, as well as the ~ROMENABLE line, which is the line you'd ground to turn off the internal ROM.

You'd install a 27128 (or equivalent) with the actual code on it in the proper locations. (You'd have 4k leftover, actually; since the on-board ROM is 4k per chip, and there's two RAM/ROM/I-O chips.)

Best part of course, is you can change the code and make the ECM do what you want. Add a fan controller or who knows what!

 

Ken73 is correct AFAIK. I have a daughter board for the C3 ecm that does just this and converts the ecm to be romless. Only one wire needs to be soldered. Now that i have the image of the roms from my '8063 I can finally convert it over and get rid of the cancerous appendage that I soldered to it so I can use eeproms and replace it with one neat chip that has it all on board.

I started a thread on this over on the DFI/ECM board that goes over how to convert it over. Not too difficult. Thankfully, RBob was nice enough to tell us how to do it.:hail:

 

Which thread?.
At TGO?.

 

Link


With the schematics its a good walk through on how to do it. Looks like it got a bump as well. Should be at the top of the message board.

 

Thanks! That link is just what I needed. At this point it is quite a bit over my head but so was chip burning in the not so distant past. I'm looking forward to giving this method a try. Hats off to RBob.

 

Very cool. Congrats and keep us updated on your progress.
Definatly get a test bench... it'll help a ton.