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text-decoration on PET

The CBM 8296 has 4 screen pages. I tried to switch between page 0 and page 1 at each interrupt so that these two pages would look like a single page because the human eye is too slow. So I ended up in a frame rate of 25 FPS per page and that flickers a lot.

Code: 
00033A  1  78                   sei                             ; disable int while changing vector
00033B  1  A9 45                lda #<scr1
00033D  1  85 90                sta IRQVECT
00033F  1  A9 03                lda #>scr1
000341  1  85 91                sta IRQVECT+1                   ; scr1 is new IRQ vector
000343  1  58                   cli                             ; done, re-enable IRQ
000344  1  60                   rts
000345  1               
000345  1               scr1:
000345  1  A9 0C                lda #12
000347  1  8D 80 E8             sta 59520
00034A  1  A9 04                lda #4                          ; select 2nd screen page
00034C  1  8D 81 E8             sta 59521
00034F  1  A9 56                lda #<scr2
000351  1  85 90                sta IRQVECT                     ; go to scr2 next time
000353  1  4C 55 E4             jmp ROMIRQ                      ; continue at original vector
000356  1               
000356  1               scr2:
000356  1  A9 0C                lda #12
000358  1  8D 80 E8             sta 59520
00035B  1  A9 00                lda #0                          ; select 1st screen page
00035D  1  8D 81 E8             sta 59521
000360  1  A9 45                lda #<scr1
000362  1  85 90                sta IRQVECT                     ; go to scr2 next time
000364  1  4C 55 E4             jmp ROMIRQ                      ; continue at original vector
 
Oh, I understand. About the same amount of flicker as interlaced modes on an Amiga 500 with regular TV? That one is quite awful.
 
It has been quite a while since I've seen interlaced video modes on an Amiga but I remember it as very annoying.
This CBM "interlace" looks a bit better (at least what I remember) but doesn't look as good as you'd like to watch for more than a few minutes.

I hope I can try this with a CBM monitor with different phosphor, than one with very long persistence.
 
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