Hello,
I have lurked these forums for quite a while, but this is my first time asking the community for help.
I am working on a project trying to reverse engineer a Ford engine management computer from the late 80s. Most of the chips appear to be custom, or at least security through obscurity. There has been some leaked documents that cover the inner workings of the custom intel microprocessor, but there isnt much about the circuitry outside of the main microprocessor.
Ive made some feeble attempts to search for the markings on the ICs, and have come up with nothing. Some recently surfaced documents have helped me identify some as just standard 74HC logic, but others still seem to be a mystery.
One has a Texas Insturments marking, but none of the other markings help identify it. Even the documentation shows no other part numbers for these ICs leading me to believe they are custom. But im hoping the pinout will help someone tell me at least what it could be. One of the noteable pinout oddities is that the middle 4 pins (pins 4,5,12,13) are all ground, but there is only a single VCC pin (specific pin undetermined). I have attached a photo of the IC in question as well as the 2 possible pinouts from the documents I have. The photo is a bit hard to read of the IC because of the conformal coating, but it reads:
TI 809 D B
903T01
Being new to most of this, and being born in the late 80s I dont have the experience with logic ICs that im sure most of you guys have. Any help is appreciated. I am working to understand the circuitry on a relatively simple ECU (low I/O), and work up to more advanced units (higher I/O, transmission controls, Coil on plug, etc...) from the same family, to ultimately create a open source hardware board that would only require a few donor chips, as these ECUs are getting harder to come by for more popular models, but less desireable ECUs are in abundance.
Thanks