It is currently Sat Oct 21, 2017 2:34 pm

All times are UTC - 7 hours





Post new topic Reply to topic  [ 3 posts ] 
Author Message
PostPosted: Mon Mar 05, 2012 3:49 am 
Offline

Joined: Mon Mar 05, 2012 3:29 am
Posts: 3
Hi all,

been reading the forums quite a lot recently as I have been delving into the realms of nes emulation.

long story short:
I'm receiving this error:
FAIL OP : $28
Unknown Error
$F93C

$28 is PLP
I noticed the 16bit value changes when I execute more/less cycles in the instruction (the shown value is for 4 cycles)

My emu is based off bisqwit's amazing 900line emu, i had attempted nes emu development multiple times before but without much experience and knowledge I always got stuck, best I reached was SMB intro shown badly (tiles and colors messed up) but bisqwit's opened my eyes to accurate emulation ( 3 ppus & 1 apu each cpu cycle, properly placing tick functions in the opcodes that execute those ppu and apu cycles )

if anyone can point me to which part of the cpu i should be fixing i'd appreciate it.


Top
 Profile  
 
PostPosted: Mon Mar 05, 2012 5:01 am 
Offline
User avatar

Joined: Fri Oct 14, 2011 1:09 am
Posts: 248
Having the source code should help a bit.

EDIT: My script for plp was:

[1450] => tick(); t = Pop();
[1740] => P.raw = t & ~0x30;
[1299] => tick();

I.e. one cycle for opcode fetch (implied)
One extra cycle
One cycle for RAM fetch
One extra cycle

For a total of 4 ticks.

Are you sure your NMI timing is fine? cpu_timing_test6 (which you seem to be running) depends on proper NMI timing.


Top
 Profile  
 
 Post subject:
PostPosted: Mon Mar 05, 2012 12:47 pm 
Offline

Joined: Mon Mar 05, 2012 3:29 am
Posts: 3
Thanks for sharing that, am doing PLP about the same as you mention.

however am not so sure about my NMI handling now, I need to revise the code( don't have access to it atm )

thanks for the info hopefully I'll work on it further and post my findings.


Top
 Profile  
 
Display posts from previous:  Sort by  
Post new topic Reply to topic  [ 3 posts ] 

All times are UTC - 7 hours


Who is online

Users browsing this forum: No registered users and 8 guests


You cannot post new topics in this forum
You cannot reply to topics in this forum
You cannot edit your posts in this forum
You cannot delete your posts in this forum
You cannot post attachments in this forum

Search for:
Jump to:  
Powered by phpBB® Forum Software © phpBB Group