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Code Block
languagenone
titleRST 20H, DEFW $D2
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

Internal operating system usage. 
Since page are on 256 byte boundaries
Since a memory page is on a 256 byte boundary, the L register is ignored.
OS_Axp might be useful for applications; when properly allocating 512 bytes or more contiguous memory area. The first page is allocated with OS_Mal. Next pages are allocated with OS_Axp specifying B and H+1 (and more...).

Bugs

Useless call which contains many design bugs :
  • IX handle is not verified.
  • Refers to OS push frame which is not stacked before call.
    • Corrupts segment 1.
     Refer to explicit memory allocation for further informations. 

    Related calls

    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