Re: [cc65] Hello, and a memory corruption (?) issue when optimizing

From: Maik Merten <>
Date: 2013-06-10 19:00:05
Am 09.06.2013 21:25, schrieb Ullrich von Bassewitz:
> It might be a problem caused by the source, not by the compiler. So yes, will
> have to give it a closer look.

Okay, now I dug a bit deeper. I'm still not quite fluent with C64 
development in general, so your advise on using Vice's monitor 
functionality for sure was a good one!

Things I tested:

  * I made sure that the bitmap data for the title screen is indeed 
included correctly in the optimized binary. I found the data to start at 
offset 0x165f.

  * Directly after loading the program with LOAD "*",8 (which should 
load the binary with an offset of $0801 into memory) I dumped the memory 
from 0x1e60 to 0x4571 into a file.

  * After starting the program (and displaying the corrupted image) I 
did another memory dump from 0x1e60 to 0x4571. Both dumps are identical, 
so I think I can rule out that the original bitmap data got messed up.

This is interesting to toy around with. From the looks of the 
corruption, I'd guess that either the video-RAM or color-RAM ends up 
with wrong values. I should dump those memory when displaying the 
corrupted image and compare.


To unsubscribe from the list send mail to with
the string "unsubscribe cc65" in the body(!) of the mail.
Received on Mon Jun 10 19:00:17 2013

This archive was generated by hypermail 2.1.8 : 2013-06-15 17:37:38 CEST