1 1 9.29.2.3 Register Names 1 ....................... 1 1 General-purpose registers are represented by predefined symbols of the 1 form 'rN' (for global registers), where N represents a number between 1 '0' and '15'. The leading letters may be in either upper or lower case; 1 for example, 'r13' and 'R7' are both valid register names. 1 1 Register names 'PC', 'SP' and 'SR' cannot be used as register names 1 and will be treated as variables. Use 'r0', 'r1', and 'r2' instead. 1