Search found 3 matches

by selassje
Thu Oct 08, 2020 7:55 pm
Forum: NESemdev
Topic: Help in understanding 7-dmc_basics.nes - test 19
Replies: 0
Views: 4839

Help in understanding 7-dmc_basics.nes - test 19

Hi, Looking at the code of that test : set_test 19,"There should be a one-byte buffer that's filled immediately if empty" setb $4013,1 setb SNDCHN,$10 lda #$10 : and $4015 bne :- delay_dmc 4 delay 30 setb $4013,0 setb SNDCHN,$10 lda $4015 and #$90 cmp #$80 jne test_failed setb SNDCHN,$10 jsr should_...
by selassje
Sat Sep 19, 2020 7:23 pm
Forum: NESemdev
Topic: VBL Clear time
Replies: 3
Views: 2527

Re: VBL Clear time

Thanks
by selassje
Sat Sep 19, 2020 7:01 pm
Forum: NESemdev
Topic: VBL Clear time
Replies: 3
Views: 2527

VBL Clear time

Hi, I am a bit confused about when the VBL flag should be cleared. The wiki page on PPU registers states : cleared after reading $2002 and at dot 1 of the pre-render line. I assume they mean PPU cycle = 1 here. However the page on PPU frame timing states : it's cleared at the start of the pre-render...