Frozone212

I hate having short term memory.

could you give an example?

Whether you're writing and assembly program on a c64, Apple 2 or Atari 8-bit, you've got (basically) the same instructions: LDA, STA, ADC, etc.  The language is the same.  How you get something on screen or out of hte speaker is totally different though.  I haven't done assembly on any of those machines in so long I don't remember, so I had to look it up quick, but for example here is a reference of gfx-related memory map on c64: https://www.chibiakumas.com/6502/c64.php

If you store a values into $D020 you will change the background color.

On Atari 8-bit, graphics are handled by a different chip, different processes and different memory addresses: https://www.atariarchives.org/agagd/chapter1.php

The c64 has 8 sprites controlled by a set of memory locations specific to the VIC2 chip, the A8 has player/missile graphics (controlled by a different set of memory locations specific to the ANTIC chip), and the Apple 2 uses shape tables not sprites.

That's the idea - you still use the same 6502 assembly instructions on each machine, but the graphics and sound chips are all very different.

Same concept applies for any computer. Hope that helps! I'm no assembly programmer, I know enough to do simple things and debug, but I'm not the person to answer any detailed questions and I hope I didn't post anything blatantly incorrect above - I was trying to convey the idea more than details on how to program each machine.

When attempting to program a chip like a VIC-II or SID, it’s always best to take a look at their datasheets. They describe, well, how they are programmed. What all the registers are and what they do and how to use them. They might be difficult to understand at first, but it is key to figuring out how to use the chip to do things in a computer system.