Sorry I meant to ask what 6502 system you are developing for.

I am unaware of a real 6502 that has its screen at $0200.
It would be a pity if you develop a game and it only runs on a PC in a simulator.

Obviously you are using a simulator or emulator, which one is this?

André

No I am not even ...

I am absolutely

Great you managed to fix it! First steps into a new world!

What you haven't told us (or I missed it), what system are you working on/for?

André

I am learning assembly languages and I wanted to use an assembly language where accessing the display is very easy so I can draw graphics on it. To ...

An additional comment:

You do an operation that sets the flags, then do some other operations, and only then check the flag.
When you further work with the code, it is easy to forget about that and insert other operations that change the flags. For example, if you want to change the loop to invert ...

Yes you are correct thanks for telling. I almost forgot that LDX is used for position.

Can you see why your code doesn't work? It's worth spending a little time walking through it yourself instruction by instruction to see exactly what it's doing, and think about how that differs from what you expected.

Spoilers below:

I assume you have a 32x32 display, with each pixel being ...

Can you see why your code doesn't work? It's worth spending a little time walking through it yourself instruction by instruction to see exactly what it's doing, and think about how that differs from what you expected.

Spoilers below:

I assume you have a 32x32 display, with each pixel being ...

I am new to 6502 programming. I wanted to make a game using this assembly language. My first program fills the whole display with white pixels.
Code:

ldx #$ff
lda #$01
drawPixel:
dex
cpx #$00
sta $0200,x
sta $0300,x
sta $0400,x
sta $0500,x
bne drawPixel
brk

However it is not doing it ...