Since one of the parameters of the MakeFunctions routine is the name of the library a good starting point might be a string containing exec.library (which is the standard name of this library in the Amiga system). So I know that somewhere that function is invoked on the code that I am studying. I know that MakeFunctions is used to create in memory the structure of Exec itself. The purpose of the present investigation is to find the Kickstart 1.3 vector table, and with that to find the position and implementation of the Exec functions. The practice of understanding how a system works starting from the pure implementation is called 'reversing', and personally I consider it one of the most fascinating tasks a programmer can face. Moreover, there is no trace of the original labels used by the author(s) of the code, as they are lost in the translation to machine language, when they are converted to pure addresses. The disassembler has no way to know if some binary number represents an instruction or a pure number. What you get is the one to one interpretation of the binary values according to the processor's conventions, and this includes parts of the binary file that are pure data. Well, not with a simple disassembler like vdasm, anyway. When you disassemble some binary code, however, you don't get some nice source code written in a high level language. The mandatory disclaimer: to use the Amiga Kickstart ROM images you must own a license. Inside this code we can see a practical implementation of the mechanism described above. $ vda68k Kickstart1.3.rom > Kickstart1.3.asm The final structure we are trying to achieve is something like this: The concept is not that complex, actually. Lisp is a good example of a higher level homoiconic language.īack to our vector table, we have to find a way to use the Exec library to install in memory the Exec library itself.

The property of treating the code as if it was pure data is called homoiconicity, and is something that can be rarely found in other languages. This is one of the powers of the Assembly language. To install Exec in memory, thus, we need to use a function which is part of the library itself. The trick here is that Exec is the library used to load in memory other libraries, so the function that creates the structure in memory of a given library is contained here. Once loaded, it has the same structure of any other library, that is a prefix containing the jump table in reverse order, then the actual code. This library is loaded in memory at boot time, and it is always open and available. The Exec library is the base library of the Amiga system.

Kickstart 1.3 rom