Routines
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E8B7: Scroll the screen down 6 rows
Used by the routine at EC7B.
E8B7 LD HL,$E7EC Set the instruction at E7EB to 'LD BC,$0020'
E8BA LD (HL),$20
E8BC LD L,$EF Set the instruction at E7EE to 'LDIR'
E8BE LD (HL),$B0
E8C0 LD B,$06 6 rows will be scrolled on
E8C2 PUSH BC Save the primary screen row counter
This entry point is used by the routine at FC6A.
E8C3 LD B,$13 There are 19 screen rows to move down
E8C5 LD DE,$5A60 DE=destination attribute file address (bottom row)
E8C8 LD HL,$5A40 HL=source attribute file address (second row from the bottom)
E8CB PUSH BC Save the secondary screen row counter
E8CC PUSH HL Save the source attribute file address
E8CD PUSH DE Save the destination attribute file address
E8CE CALL $E7E8 Move one screen row down
E8D1 POP HL HL=source attribute file address
E8D2 LD BC,$FFE0 Point HL at the next row up in the attribute file
E8D5 ADD HL,BC
E8D6 EX DE,HL Transfer this address to DE
E8D7 POP HL HL=destination attribute file address
E8D8 ADD HL,BC Point HL at the next row up in the attribute file
E8D9 POP BC Restore the secondary screen row counter to B
E8DA DJNZ $E8CB Jump back until all 19 screen rows have been moved down
E8DC LD HL,$7FFF 7FFF holds the y-coordinate of the topmost row of the play area on screen
E8DF DEC (HL) Decrement this
E8E0 LD HL,$001F L=31 (rightmost screen column), H=0 (top row of the screen)
E8E3 PUSH HL Save the screen coordinates briefly
E8E4 CALL $E70C Print a tile at screen coordinates (L,0)
E8E7 POP HL Restore the screen coordinates to HL
E8E8 DEC L Have we printed every tile in the row yet?
E8E9 JP P,$E8E3 Jump back if not
E8EC POP BC Restore the primary screen row counter to B
E8ED DJNZ $E8C2 Jump back until 6 rows have been scrolled on
E8EF RET
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