@ +1 should remain +1
SSSTN           | PUSH +1
NSTTSSSTN       | JSR > 10001 (abs)
NSTTSSTN        | JSR > 1001 (print number from stack)

@ -1 should become +1
SSTTN           | PUSH -1
NSTTSSSTN       | JSR > 10001 (abs)
NSTTSSTN        | JSR > 1001 (print number from stack)

@ 0 should remain 0
SSSSN           | PUSH 0
NSTTSSSTN       | JSR > 10001 (abs)
NSTTSSTN        | JSR > 1001 (print number from stack)

@ Test the most negative number.
@ It is impossible to return the true absolute value but should return zero.
SSSTN           | PUSH +1
SSSTTTTTTN      | PUSH +63
NSTTSTTSTN      | JSR > 101101 (lshift)
NSTTSSSTN       | JSR > 10001 (abs)
NSTTSSTN        | JSR > 1001 (print number from stack)
NNN             | DIE

#include <logic.pvvs>
#include <stdio.pvvs>