memory banks (screens)

    device zxspectrum128
; Author: Serdjuk
; Assembly: sjasmplus
    org #6000
begin:
    ld sp,#c000
    ld a,#1d
    ld bc,#7ffd
    out (c),a
    ld hl,#D800
    ld de,#D801
    ld bc,767
    ld (hl),5
    ldir
    ld a,#17
    ld bc,#7ffd
    out (c),a
    ld hl,#D800
    ld de,#D801
    ld bc,767
    ld (hl),5
    ldir
repeat:
    ei
    halt
    call bank
    call showLines
    call printSprite
    jr repeat
;----------------------------------------------------
saveSP: defw #0000
bank:
    ld a,#17
    ld bc,#7ffd
    out (c),a
    xor #0a
    ld (bank+1),a
    ret
;----------------------------------------------------
showLines:
    ld hl,#0101
    rlc l
    rlc h
    ld (showLines+1),hl
screenPart:
    ld (saveSP),sp
    ld sp,#C000+#1800
    ld b,192
cp1:
    dup 16
    push hl
    edup
    djnz cp1
    ld sp,(saveSP)
    ret
;----------------------------------------------------
printSprite:
        ld hl,sprite64x64       ; sprite address
        ld de,#c80c     ; screen address
        ld b,64      ; height
loop    push bc,de
        dup 8       ; width
        ldi
        edup
        pop de,bc
        call down_de    ; next line address
        djnz loop
        ret
down_de:
        inc d
        ld  a,d
        and 7
        jr  nz,$+12
        ld  a,e
        add a,32
        ld  e,a
        jr  c,$+6
        ld  a,d
        sub 8
        ld  d,a
        ret
sprite64x64:
    defb #00, #00, #00, #00, #00, #00, #00, #00, #00, #00, #00, #00, #00, #00, #00, #00
    defb #00, #00, #00, #00, #00, #00, #00, #00, #00, #1C, #81, #00, #00, #00, #00, #00
    defb #00, #0F, #FF, #E0, #00, #00, #00, #00, #00, #01, #FE, #70, #00, #00, #00, #00
    defb #00, #00, #50, #38, #00, #00, #00, #00, #00, #00, #40, #0E, #00, #00, #00, #00
    defb #00, #00, #40, #07, #00, #00, #00, #00, #00, #00, #60, #3F, #C0, #00, #00, #00
    defb #00, #00, #7E, #3C, #F0, #00, #00, #00, #00, #01, #FE, #3E, #38, #00, #00, #00
    defb #00, #07, #F0, #1E, #0E, #00, #00, #00, #00, #07, #F0, #1E, #03, #80, #00, #00
    defb #00, #07, #E0, #00, #00, #E0, #00, #00, #00, #07, #E0, #00, #00, #30, #00, #00
    defb #00, #07, #C0, #00, #00, #18, #00, #00, #00, #00, #C0, #00, #00, #1C, #00, #00
    defb #00, #00, #F0, #00, #00, #0C, #00, #00, #00, #00, #F0, #00, #00, #04, #00, #00
    defb #00, #00, #40, #00, #00, #06, #00, #00, #00, #00, #60, #00, #00, #06, #00, #00
    defb #00, #00, #38, #00, #00, #07, #00, #00, #00, #00, #1F, #F8, #00, #03, #00, #00
    defb #00, #00, #0F, #E0, #00, #03, #80, #00, #00, #00, #09, #FC, #C0, #03, #80, #00
    defb #00, #00, #09, #F0, #40, #03, #C0, #00, #00, #00, #1B, #C3, #60, #01, #C0, #00
    defb #00, #00, #1B, #07, #60, #01, #E0, #00, #00, #00, #1E, #02, #30, #01, #E0, #00
    defb #00, #00, #16, #00, #30, #01, #E0, #00, #00, #00, #34, #00, #18, #01, #A0, #00
    defb #00, #00, #34, #00, #18, #01, #A0, #00, #00, #00, #36, #00, #1C, #01, #A0, #00
    defb #00, #00, #26, #00, #0C, #00, #E0, #00, #00, #00, #27, #80, #0E, #00, #E0, #00
    defb #00, #00, #23, #80, #06, #00, #C0, #00, #00, #00, #21, #C0, #06, #00, #80, #00
    defb #00, #00, #21, #F0, #02, #00, #80, #00, #00, #00, #21, #FF, #83, #00, #80, #00
    defb #00, #00, #30, #FF, #FF, #00, #80, #00, #00, #00, #30, #FF, #FF, #00, #C0, #00
    defb #00, #00, #3C, #3F, #FF, #00, #40, #00, #00, #00, #16, #7D, #FF, #C0, #40, #00
    defb #00, #00, #1B, #FC, #FE, #C0, #40, #00, #00, #00, #0F, #F8, #7F, #C1, #C0, #00
    defb #00, #00, #0F, #F0, #3F, #C3, #00, #00, #00, #00, #00, #00, #1E, #CF, #00, #00
    defb #00, #00, #00, #00, #1F, #CC, #00, #00, #00, #00, #00, #00, #3F, #F8, #00, #00
    defb #00, #00, #00, #00, #3F, #C0, #00, #00, #00, #00, #06, #00, #79, #E0, #00, #00
    defb #00, #00, #0F, #00, #70, #F0, #00, #00, #00, #00, #0F, #80, #70, #78, #00, #00
    defb #00, #00, #0F, #80, #E0, #3C, #00, #00, #00, #00, #06, #C0, #E0, #1E, #00, #00
    defb #00, #00, #07, #C1, #C0, #0F, #00, #00, #00, #00, #03, #E1, #C0, #07, #00, #00
    defb #00, #00, #01, #F3, #80, #03, #00, #00, #00, #00, #00, #FF, #80, #FF, #00, #00
    defb #00, #00, #00, #FF, #01, #FE, #00, #00, #00, #00, #00, #3F, #00, #78, #00, #00
    defb #00, #00, #00, #0E, #00, #00, #00, #00, #00, #00, #00, #00, #00, #00, #00, #00