^ Thanks!
Now, back (somewhat) on topic.
Here are the pictures that DucatiCraig sent me of the 37820-PR7-A32 OBD2 95-96 NSX ECU. The OBDII NSX ECU uses the same family of processor as the 91-94 (h8/532)- the H8/500 - but it is updated with larger ROM space and more features (H8/536). What is EXTREMELY interesting is that this ECU uses a PROM version of the H8/536 instead of the MASK ROM. This was most likely done because the NSX's limited production didn't justify the cost for the MASK ROM, and for the ability to be more flexible with running changes to the coding. After a quick examination of the chip part numbers this ECU is much much more complicated than I initially thought. It has an extra MCU, the H8/330. I have to assume that this is due to the engine being drive-by-wire. I can see how control of the throttle plate could require its own processor - it needs to be extremely fast and handle the demands of the accelerator pedal, idle control and commands from the traction control system. What is intriguing, though, is that the OBD2 ECU retains the same proprietary I/O controller as the OBD1 91-94 NSX (MN73011LAQ - the OBD1 NSX uses 2 of these I/O controllers while the Legend & Vigor use 1). This means that the processor is running in expanded mode (with the address and data bus live) in order to address this chip. This ECU also uses many more surface mount components than the OBD1.
What type of interest is there in modifying this ECU? Do the 95+ owners convert back to a cable throttle when using an aftermarket EMS?
This picture clearly shows all of the part numbers for the main chips on the board.
Upper Left IC901: HD6473308CP10 (H8/330 Processor @ 10mhz)
Center IC402: MN73011LAQ (Proprietary ASIC Input/Output controller - identical to the one used on 91-94 NSX and 91-95 Legend)
Right IC401: HD6475368CP10 (H8/536 Processor @ 10mhz)
Lower IC805: HD63140CP (Hitachi Universal Pulse Processor)
The small piece of foil stamped underneath the part number is the internal ROM revision #.
Here is the RL ECU for comparison. I wont spend much time explaining the RL OBD2 ECU because it is less similar to the NSX OBD2 ECU than I initially thought. The ECU's had similar updates in that they use more surface mount technology but most of the similarities end there. The RL got the updated H8/536 but it is the MASK ROM version and is running in Mode 7 - single chip mode with no outside address or data bus active, and it doesn't use the proprietary I/O controller. Also, on the RL, the automatic transmission controls are integrated on the same board, the lower H8/532 processor is for the A/T.
I also took a picture of the home made MCU reader thats used to read the ROM on the processor.
-Matt
