nesdev.org

Posted: **Wed Jun 28, 2006 10:55 am**

Bregalad wrote:I think have emulator hide top and bottom borders is a good thing, even if it doesn't really emulate the hardware

It does emulate the hardware for the same reason that the NTSC-filter in Nestopia emulates the hardware: the TV monitor is part of "the hardware".

Posted: **Wed Jun 28, 2006 9:33 pm**

Celius wrote: store #5 in $4014, because #5 is the high byte of $500. Do you understand?

With that in mind, When i see a LDA #$1 does that mean its pointing to the Stack. Heres the Example in code:

Code: Select all

b6:				;#A_BUTTON bRANCH
	lda     #$01            
	ldx     CUR_BIT
	beq     +
	clc
-
	asl
	dex
	bne     -
+
	pha			;Push accumulator on stack
	lda     CUR_CHN
	asl
	asl
	clc
	adc     CUR_REG
	tax
	pla			;Pull accumulator on stack

	eor     SND_REGS,x
	sta     SND_REGS,x
	rts

[/code]

Posted: **Wed Jun 28, 2006 9:40 pm**

nineTENdo wrote: With that in mind, When i see a LDA #$1 does that mean its pointing to the Stack. Heres the Example in code:

no no.

It is true that the $01xx page is the stack -- that's a good observation. However the behavior you're talking about only happens on writes to $4014 (the sprite DMA register).

Code: Select all

lda #$05
sta $4014

That code will copy the $05xx page to Sprite RAM -- but it's not the LDA line that does it, it's the STA line (since that's the instruction performing the write).

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