Understanding video memory and pages
Posted: Wed Oct 07, 2015 10:51 am
Hi,
I think I haven't understood very well how video memory and pages works in a Dragon 32/64.
So far, I understand how to set the highest resolution #4, 256x192 two colors, using machine code:
And the memory that it needs is 6144 bytes. Which I'm not sure is the next statements, and I hope you can tell me which one are true:
- We have 2 pages in that resolution
- The page #0 starts at $0600 and the page #1 starts at $1E00
- I can use the addresses $FFC6 <-> $FFD3 to choose the page we want to show
- I can write values from $0600 to $1DFF to update page #0
- I can write values from $1E00 to $3600 to update page #1
I'm trying to do an animation using 2 pages, but so far I haven't got it, so there is something I'm wrong.
Thanks for your help!
I think I haven't understood very well how video memory and pages works in a Dragon 32/64.
So far, I understand how to set the highest resolution #4, 256x192 two colors, using machine code:
Code: Select all
STA $FFC0 ; [SAM VDG Reg V0]
STA $FFC3 ; [SAM VDG Reg V1]
STA $FFC5 ; [SAM VDG Reg V2]
- We have 2 pages in that resolution
- The page #0 starts at $0600 and the page #1 starts at $1E00
- I can use the addresses $FFC6 <-> $FFD3 to choose the page we want to show
- I can write values from $0600 to $1DFF to update page #0
- I can write values from $1E00 to $3600 to update page #1
I'm trying to do an animation using 2 pages, but so far I haven't got it, so there is something I'm wrong.
Thanks for your help!