Search found 15 matches

by LukasP
Thu Jun 06, 2019 5:04 am
Forum: NESemdev
Topic: Joystick issue
Replies: 4
Views: 10667

Re: Joystick issue

@lidnariq you were totally correct about the CPU issue. Tired of shooting in the dark I just went to NMI of a balloon fight and just looked what are the instructions used inside of it. There were only several so I hand checked them super super carefully and found a bug in my LSR routine. Now i'm ama...
by LukasP
Thu Jun 06, 2019 4:18 am
Forum: NESemdev
Topic: Help with graphical artifacts with Mario Bros in PPU.
Replies: 3
Views: 8625

Re: Help with graphical artifacts with Mario Bros in PPU.

How did you imlement your PPU? Can you print out and compare with working emulator that you indeed get correct nametable indexes at those positions? How do other UNROM games look like in your emulator? I've had similar issue with my first PPU iteration which was - render everything in one go each fr...
by LukasP
Wed Jun 05, 2019 11:53 pm
Forum: NESemdev
Topic: Help to identify PPU timing issue
Replies: 11
Views: 10365

Re: Help to identify PPU timing issue

I just wanted to make an update on the issue as I've fixed it. This was totally a CPU bug cause by a faulty LSR instruction. Nestest why did you betray me... :D // below is fixed code // this.P[0] &= 0b11111110; // this.P[0] |= (val & 1); // below is old not working code this.P[0] &= 0b11111110 | (v...
by LukasP
Mon Jun 03, 2019 7:08 am
Forum: NESemdev
Topic: PPU BG rendering question
Replies: 4
Views: 4905

Re: PPU BG rendering question

Thanks @tokumaru for additional insight however that only makes sense once you've already glued the things together, like for example I must know from another wiki page that background tiles consist from 2 planes which is fine and I've already implemented it now, however it could be at least a menti...
by LukasP
Mon Jun 03, 2019 4:19 am
Forum: NESemdev
Topic: PPU BG rendering question
Replies: 4
Views: 4905

Re: PPU BG rendering question

So it finally clicked for me it was just unfortunate timing to create this thread after a long time of digging into PPU. So from my understanding there are 2x16bit registers and those 2 are for both planes of pattern, Plane0 and Plane1, so each register contains just 1 bit of each, making 16pixels i...
by LukasP
Mon Jun 03, 2019 1:02 am
Forum: NESemdev
Topic: PPU BG rendering question
Replies: 4
Views: 4905

PPU BG rendering question

I have PPU working mostly by accident but can't fully explain it so I would like to know more about background rendering. I've read and re-read wiki on PPU rendering but still have questions, like it states that there are 2x 16 bit registers. My guess is that one is for plane0 and one for plane1. Th...
by LukasP
Thu May 16, 2019 12:51 am
Forum: NESemdev
Topic: Joystick issue
Replies: 4
Views: 10667

Joystick issue

My joystick does work on Balloon Fight, Bomberman, however in Balloon fight it doesn't work. I pass nestest and Blarrg's CPU test and I have no idea why it could not work. Controller code is checked rechecked and rewritten few times still to no avail. Now I have an idea maybe it's somehow related to...
by LukasP
Fri May 10, 2019 2:26 pm
Forum: NESemdev
Topic: Help to identify PPU timing issue
Replies: 11
Views: 10365

Re: Help to identify PPU timing issue

So in the end I was the moron and finally debugged the issue into my... SWITCH statement where I forgot to add breaks, asserted stuff all over the place until clock started to assert which didn't match the main loop. I don't use switch statements, I prefer if-else pairs or just an array with callbac...
by LukasP
Tue May 07, 2019 10:37 pm
Forum: NESemdev
Topic: Help to identify PPU timing issue
Replies: 11
Views: 10365

Re: Help to identify PPU timing issue

@koitsu you've given a lot of details, thank you. I totally agree with you that I am too dependant on the tests however I see no way of coding something as complex as cycle perfect PPU in one go. Some intermediate results may be wrong and the output may yield nothing in return, so running some tests...
by LukasP
Tue May 07, 2019 10:31 pm
Forum: NESemdev
Topic: Help to identify PPU timing issue
Replies: 11
Views: 10365

Re: Help to identify PPU timing issue

thanks @Dwedit for an explanation! That sheds me a lot of light into the problem. I immediately went to see what is up in the main fetching loop and noticed the issue in attribute fetching code which now is fixed and looks like the attached image. So the strange tearing is now gone! The only issue l...
by LukasP
Mon May 06, 2019 11:10 pm
Forum: NESemdev
Topic: Controller not working for some games ?
Replies: 2
Views: 6304

Re: Controller not working for some games ?

Did you run nestest CPU test? I have problems with controller as well but nestest run's 100% flawlessly for me
by LukasP
Mon May 06, 2019 11:05 pm
Forum: NESemdev
Topic: Help to identify PPU timing issue
Replies: 11
Views: 10365

Re: Help to identify PPU timing issue

@Dwedit thank you! Could you tell me some possible methods to check intermediate steps? Like what you would do? It's a lot of guesswork where I'm not sure where to start thus I've started to run Blarrg's PPU tests to see the deeper issue but I don't think they can help me much here. At least I see n...
by LukasP
Mon May 06, 2019 10:38 pm
Forum: NESemdev
Topic: Help to identify PPU timing issue
Replies: 11
Views: 10365

Help to identify PPU timing issue

Hello. I've been doing cycle accurate PPU for a while but it just isn't finished ever. My test rom is Balloon fight as for other rom's I've not imeplemented proper mirroring of things so I just see garbage. Can someone shed some light by intuition where should I look at? For me it looks like X is be...
by LukasP
Tue Apr 02, 2019 11:00 am
Forum: NESemdev
Topic: Direct PPU rendering possibilities?
Replies: 5
Views: 6052

Re: Direct PPU rendering possibilities?

Thanks everyone for chiming in about suggestions. @lidnariq on donkey kong I see this as a title screen: https://puu.sh/D94Z5/1fc79dc792.png And this once the game starts to play itself: https://puu.sh/D94YS/b515ee0ca2.png My emulator passes nestest rom recommended in wiki by 100%. I am mostly think...
by LukasP
Mon Apr 01, 2019 11:26 pm
Forum: NESemdev
Topic: Direct PPU rendering possibilities?
Replies: 5
Views: 6052

Direct PPU rendering possibilities?

Hello everyone. So currently I have somewhat bare bones PPU implementation which parses pattern tables and nametables and displays them. I do this in a direct rendering mode - just scan the nametables, stitch the patterns and display everything. My goal is to emulate Donkey Kong at first. I do not c...