Reading The EPROM
Reading EPROMs is easy. All you need to do is cut the goo that holds the chip onto the board, pry it up carefully with a flat screwdriver, and drop it in your EPROM reader. If you don't have an EPROM reader, there is really no reason to buy one. It is a whole lot easier to just find a website with the EPROM contents already read into a file. Google that, if you want.
I had an ancient EPROM reader from way back. How ancient? It interfaces to my PC via a parallel port. Whatever, it worked, so I went that route.
What you get out of the reader is a binary file that is 32K bytes long containing the contents of every memory location in the EPROM starting from EPROM address 0. It is quickly obvious that this information is useless in that format. The ECU processor can understand the binary data perfectly, but certainly not people. To make the binary data human-readable, we need to "disassemble" the code.