From Newsgroup: comp.sys.cbm


Roger Levy wrote ...

the question is, what would be the easiest way to get the kernal ROM to >"stop" scrolling the colors upward at a certain line of the color RAM? the >c128 had a way to create a window, but i dont think c64 has that. this
sucks. somebody?

Sorry, I don't remember which issue it was in, but LoadStar published a
Basic add-on that allowed using windows on the C64. Might not help you
though as you are using Forth instead of Basic.

Best regards,

Sam Gillett aka Mars Probe @ Starship Intrepid 1-972-221-4088
Last 8-bit BBS in the Dallas area. Commodore lives!





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From Newsgroup: comp.sys.cbm

i was able get the job done with this code i wrote: (my thanks go to Paul
for the helpful link)

; uses $10 and $11 of ZP
lda #$00
tay
sta $10
lda #$e0
sta $11
copy_kernal_ram_to_e000:
lda ($10),y
sta ($10),y
clc
lda $10
adc #1
sta $10
lda $11
adc #0
sta $11
bne copy_kernal_ram_to_e000

;switch rom out
lda #$35
sta $01

; set kernal to only scroll lines up to the following line#: reg_text_scroll_line=*+1 ;<----- i like to do this so the system is configurable from FORTH without using variables :)
lda #20
sta $e8f7

;of course, e000-ffff is now unusable. but if i ever discover more useful
hacks for the ROM, now i know i can do it. :)


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