VW Digifant ECU

[Lou Faustini]

>Merry Christmas and a Happy New Year to everyone!
>
>Has anyone dug into the Digifant FI, and its potential for modification,
>of VWs, 88-92 Golfs and Jettas? Currently there are no aftermarket chips
>available for this ECU.
>The architecture is a dual processor one: An intel 8039 for the fuel
>control, that chip has its code in a 2764 EPROM, and has a TI ADC 0809
>attached to it. The other processor is a Motorola 6805 variant for the
>ignition control. The processor itself is marked SC 80984, and is EPROM
>programmable. Has anyone heard about this particular chip?
>Any information and discussion on the above would be much appreciated!
>


   Peter, I have not dug into that FI system, but I can tell you a little 
about the CPU's they are using. I -think- that I remember the Intel 8039 as 
a real small micro-controler. Its real funny to program, if I remember 
corrrectly, its adress space is limited to 1k chunks. the upper adress lines 
are bank-switched through software. (sounds like an Intel product eh?) That 
means its a real pain to write lengthy code on. The factory probly kept the 
software very simple on this chip. They kinda had to. I bet the code isn't 
much moore than a look up table. The fuel injection map is probly resides in 
that externam eprom. I also think the 8039 has about 1k of internal EPROM.  
Is the EPROM socketed? If so, pull it out and read it into you're PC. I will 
look up the docs on the 8039 for you, and let you know where the CPU starts 
out of reset. (I -think- its at $0000 ) If you hand-disasemble the code at 
the reset-vector location, and it appears to make sense, then you are on to 
something. If that chip truly contains a simple program to do look up it 
wont be too hard to completly disassemble the code, and figure out how their 
fuel map works.. Hope this helped..



                         ------ Lou Faustini