603 may refer to: 603 (number), the natural number following 602 and preceding 604 A year: 603 CE or 603 BCE The North American telephone area code 603 The US state of New Hampshire, which solely uses the 603 area code. The IBM 603 Electronic Multiplier The PowerPC 603 microprocessor The socket 603 motherboard socket for the Intel Xeon microprocessor Minor planet 603, named Timandra The Tatra 603 automobile The Bristol 603 automobile The Daimler-Benz DB 603 aircraft engine The Mercedes-Benz OM603 diesel engine The large number 10603, known as ducentillion (USA and modern British) or thousand centillion (traditional British) or centilliard (traditional European)