Hello everybody!
I'm currently following bunnyboys programming tutorial and for so far i more or less understand it.
But this piece of code keeps bothering me:
I don't know what NMI means, i do know kinda what it does. It's the piece of code that updates the sprites right?
http://www.nintendoage.com/forum/messageview.cfm?catid=22&threadid=4440
I get why i need to tell the cpu where to store all the titles in the ram at ($0200)
at least that's what i understand from the tutorial: http://www.nintendoage.com/forum/messageview.cfm?catid=22&threadid=6082
Now here's my problem: I get why i would write to 2003 (because it's a ppu I/O port)
But WHY do i need to write the higher byte to $4014??????
looking at the nes Architecture http://www.nintendoage.com/forum/messageview.cfm?catid=22&threadid=4291
I'm writing the $02 to an adress somewhere in the APU/controler I/O ports.
Sorry if this is a simple or stupid question but i could realy pull my hair out now.
Thanks in advance!
I'm currently following bunnyboys programming tutorial and for so far i more or less understand it.
But this piece of code keeps bothering me:
Code:
NMI:
LDA #$00
STA $2003 ; set the low byte (00) of the RAM address
LDA #$02
STA $4014 ; set the high byte (02) of the RAM address, start the transfer
RTI
LDA #$00
STA $2003 ; set the low byte (00) of the RAM address
LDA #$02
STA $4014 ; set the high byte (02) of the RAM address, start the transfer
RTI
I don't know what NMI means, i do know kinda what it does. It's the piece of code that updates the sprites right?
http://www.nintendoage.com/forum/messageview.cfm?catid=22&threadid=4440
I get why i need to tell the cpu where to store all the titles in the ram at ($0200)
at least that's what i understand from the tutorial: http://www.nintendoage.com/forum/messageview.cfm?catid=22&threadid=6082
Now here's my problem: I get why i would write to 2003 (because it's a ppu I/O port)
But WHY do i need to write the higher byte to $4014??????
looking at the nes Architecture http://www.nintendoage.com/forum/messageview.cfm?catid=22&threadid=4291
I'm writing the $02 to an adress somewhere in the APU/controler I/O ports.
Sorry if this is a simple or stupid question but i could realy pull my hair out now.
Thanks in advance!