;; This example shows how to split the screen using the CPC+ ;; If you want to do the same effect on the CPC, then you will ;; need to use the "rupture"/"vertical splitting" technique. ;; ;; This example is designed for CPC+ only and will ;; not work on CPC or KC Compact. ;; ;;;; This example will compile with the MAXAM assembler ;; or the built-in assembler of WinAPE32. ;; NOTE - For this example to work, the code must not ;; be in the range &4000-&7fff inclusive. The ASIC registers ;; are paged into this range, and the code would not be ;; visible to the CPU if it was also in this range. org &8000 ;;-------------------------------------------------- ;; STEP 1 - Unlock CPC+ additional features ;; unlock asic to gain access to asic registers di ld b,&bc ld hl,sequence ld e,17 .seq ld a,(hl) out (c),a inc hl dec e jr nz,seq ei ;;--------------------------------------------------- ;; STEP 2 - Set display start address for display before split ;; this address corresponds to a start of &c000 ld hl,&3000 ;; set display start address (high) ld bc,&bc0c out (c),c inc b out (c),h ;; set display start address (low) ld bc,&bc0d out (c),c inc b out (c),l ;;--------------------------------------------------- ;; STEP 3 - Set display start address for display after split ;; ;; - The split is refreshed by the ASIC, so as soon as it has been initialised ;; it will remain active until it is disabled (by writing 0 as the scan-line for the split) ;; No extra CPU time is required to maintain the split. ;; ;; - The split address is defined the same as the CRTC display start address ;; ;; - The split address is in the same order as the CRTC display start address ;; (high byte followed by low byte) ;; page-in asic registers to &4000-&7fff ld bc,&7fb8 out (c),c ;; set scan-line that split will activate on ld a,100 ld (&6801),a ;; set screen address of split: ;; this address corresponds to start of &4000 ld hl,&1000 ld a,h ld (&6802),a ld a,l ld (&6803),a ;; page-out asic registers ld bc,&7fa0 out (c),c ;;---------------------------------------------------- ret ;;---------------------------------------------------------- ;; this is the sequence to unlock the ASIC extra features .sequence defb &ff,&00,&ff,&77,&b3,&51,&a8,&d4,&62,&39,&9c,&46,&2b,&15,&8a,&cd,&ee