DEF SEG = &HFFFF
Byte% = PEEK(14)
DEF SEG
SELECT CASE Byte%
   CASE 255: PRINT "IBM PC"
   CASE 254: PRINT "IBM XT"
   CASE 253: PRINT "IBM PCjr"
   CASE 252: PRINT "IBM AT o superiore"
   CASE ELSE: PRINT "Identificativo sconosciuto"
END SELECT