hello.z80

  ld bc,08000h
  ld h,c
  ld l,c
sqrloop:
  srl b
  rr c
  add hl,bc
  ex de,hl
  sbc hl,de
  jr c,sqrbit
  ex de,hl
  add hl,bc
  jr sqrfi
sqrbit:
  add hl,de
  ex de,hl
  or a
  sbc hl,bc
sqrfi:
  srl h
  rr l
  srl b
  rr c
  jr nc,sqrloop