25 OUT &H313,&H90:OUT &H311,97:IF INP(&H311)<>97 THEN A=&H210 ELSE A=&H310
30 B=A+1:C=A+2:Z=A+3 'define ports A,B,C and Control word address
40 OM=&H80:IM=&H90 'Define two control words for writing and reading clstem disk or disk error<UNK! {000D}><UNK! {000A}>Replace and strike any key when ready<UNK! {000D}><UNK! {000A}>