CODE _blank ( this is way too slow in Forth )
A XORr, VDP_CTLPORT OUTiA,
A 0x40 LDri, VDP_CTLPORT OUTiA,
HL 0x4000 LDdi,
BEGIN,
A XORr, VDP_DATAPORT OUTiA,
HL DECd, HLZ,
JRNZ, AGAIN,
;CODE