OS_Axp, Allocate explicit page

Register parameters

IN:
     IX = memory handle
     B = explicit bank
     H = explicit page

OUT, if call successful:
     Fc = 0, OK

OUT, if call failed:
     Fc = 1
          A = RC_FAIL, failed to allocate memory


Registers changed after return:
     ..BCDEHL/IXIY same
     AF....../.... different

Notes

OS_Bix, Bind in extended address
OS_Box, Restore bindings after OS_Bix
OS_Fc, Select fast code (fast bank switching)
OS_Mal, Allocate memory
OS_Mcl, Close memory (free memory pool)
OS_Mfr, Free (previously allocated block) memory
OS_Mgb, Get current bank binding in segment
OS_Mop, Open memory (allocate memory pool)
OS_Mpb, Set new bank binding in segment
OZ_Mgb, Get current bank binding in segment
OZ_Mpb, Set new bank binding in segment