illegal memory address(while drawing own pattern)

[boodoomer]

I'm trying to draw own black-white dot-pattern, it works separately, but with keybord loop it doesn't

<ASM>
  @digit //0101010101010101 const in memory R0
 (KBDLOOP)
  @i // SCREEN address with offset
  A = M
  M = D //illegal memory adress -negative-number

  ...
<ASM>

[WBahn]

There's no way to tell what you are doing wrong based on this code snippet.

One thing that is certain is that your @digit instruction has no effect since it is immediately followed by @i.

What is setting the value of i? THAT is the code you need to be focusing on, because that value is getting set to a value outside the range of valid RAM addresses.