Re: A85: ROM Browser


[Prev][Next][Index][Thread]

Re: A85: ROM Browser




The program you suggest would probably find most functions, but I am not
sure whether it would be very useful. The problem is that only a small
part of what is stored in the system mem has been descirbed. A lot of the
function which has not been desriebed yet uses many of these addresses,
which makes it very hard to understand what they are doing. Most of the
Basic functions consist of almost nothing but calls to unknown functions,
which makes it even harder to understand what they are doing. So unless
you have an idea of what the function might be doing before you start
disassembling it, it is almosty impossible to find out what it does.

Using a program like the one you are suggesting would return a lot of
functions, and it would be very hard to figure out which of them to have a
look at. Some of the functions the program would find would probably be
disassembled data, which makes no sense. 

My suggestion to anyone who wants to find functions in the ROM is
therefore to use other methods to finds the functions to disassemble. If
you know what kind of functions you are looking for it is normally not
hard to find the area where they are placed.

Dines

__________________________________________

Dines Justesen
Email: c958362@student.dtu.dk
WWW  : http://www.student.dtu.dk/~c958362/
__________________________________________

On Thu, 24 Sep 1998, Humberto Yeverino wrote:

> 
> When I said just look for ret intructions I hadn't put a lot of thought
> into "routine finding."  I can still be done of course.  Any non
> conditional jp or ret that can't be bypassed would mean the end of a
> function. Ex:
> 
> TI_MUL:
> ld a,(hl)
> ...
> jr z,Overflow
> add a,24
> ret
> Overflow:
> ret c
> ld a,0
> ret
> *FUNCTION ENDS HERE*
> 
> My previous method seemed a little too simple.  So my current method would
> be scan for absolute rets and jps, if a conditional jr or jp is
> encountered, follow it only if it jumps forward, continue searching for
> absolute jps and rets...
> I don't think I overlooked anything this time.
> 
> I would write a program like this but I've got lots of work, and midterms
> are coming up.
> 
> later,
> 
> -Humberto Yeverino Jr.
> 
> "I kick ass for the Lord."
> 
> ***********************************************************
> Home Page:                                               
>   http://www.engr.csufresno.edu/~humberto/Home.html      
> 
> Ti Page:                                                 
>   http://www.engr.csufresno.edu/~humberto/tex.html       
> 
> z80 Source Page:                                         
>   http://www.engr.csufresno.edu/~humberto/z80source.html 
> 
> Official Tyrant Home Page:                              
>   http://www.engr.csufresno.edu/~humberto/tyrant.html    
> 
> E-mail:                                                  
>   humberto@engr.csufresno.edu                            
> ***********************************************************
> 
> 


Follow-Ups: References: