cpik uses 6 16 bit pseudo-registers named _r0,_r1,_r2,_r3,_r4 and _r5. These registers are located in page 0, and are efficiently accessed via Access Bank (a=0).
W is used as a general purpose scratch register
_r0 is the 16 bit equivalent of W,
_r1 to _r5 are used by the Run-time library (RTL),
FSR0 is the software stack pointer,
FSR1 is a general purpose address register,
FSR2 is used for fast memory moves together with FSR1,
PRODL and PRODH are used for arithmetics and temporaries
INDFx, PREINCx, POSTDECx, and PLUSWx are intensively used
and also accessed in Access Bank for efficiency reasons.