dirk103 wrote:
Heyo
I'm working on learning on some 6502 assembler and there's something i'm having a little trouble with.
I want to write a sub routine (for my c64) that will display a box in the screen. (Text only)
I want to position the box with x, y, w, h.
I'm just wondering what the easiest/most common way to access the video memory would be. I want to store a 16bit pointer to the current position I'm writing to so that I may increase both the lsB and msB.
Also if you happen to have a link or some code laying around that shows the basic way to work with 16 bit addition. That's be awesome. I don't understand where the data to add to the msB with a ADC instruction codes. I understand that the Carry bit is set, but this alone isn't enough to complete an Add.
Thanks a ton! It's awesome there's such a popular forum on the web for this classic CPU
There is all sorts of stuff around here that can help you out. Like finding Blackbeard's treasure, you need to do a little digging. As for using the 65xx instructions themselves, enough paper has been printed about that to sink a small ship.