Almost all OBD1 ECUs used in 92-95 Civics and integras (but NOT preludes, accords, legends, etc.) are more or less electrically compatible. With minor tweaks, all sorts of ECUHardware Mods are possible. OBD1 Code Compatibility describes how to mix and match code and ECUs.

This generation of ECU uses a 66207 MCU. Most ECUs ship with the program to run them in internal ROM.

The provision for an external ROM was made in the board design, and it can be activated by adding a 74 HC373, a resistor, two capacitors, J1 and a socket for the ROM itself. <- This mostly refers to the USDM ECU's. I have not seen evidence otherwise for JDM as most already have external ROM's present. Not sure for EDM .

The 82 C55 chip present on the ECU board is an IO controller that is used to drive most outputs.

J12 controls how the ECU's serial interface works. Important for Data Logging.

dj_spark - 21 Feb 2006 : EDM P28/P30 ECUs are modded in the same way by adding the same components like the USDM version.