// 28b. Stable, but switching colour quite a few cycles too late.
// Overwrites most of the kernal's CHRGET routine residing on zero page from $73 onwards.
// X=$FF and Y=$01 when kernal enters the routine, hence saving a couple bytes taking advantage of this.
            * = $75
blue:       lda #$26
            sta ($85,x)     // sta $d011, disables screen
            nop $DEAD       // value gets overwritten by kernal, thus wasting 3 bytes here
setcol:     sta $d020       // set colour to $x7 (yellow) or $x6 (blue)
loop:       lda (<d011+1),y // lda $d012
            bne check_yel
d011:       lda $d011
            bpl blue        // set to blue if on rasterline 000
check_yel:  cmp #$97        // chosen colour switch rasterline also used to set col to yellow
            bne loop
            sei
            beq setcol