DOS Fn 5801H: Set Memory Allocation Strategy

                                                         Compatibility: 3.0+ 
 Expects: AX    5801H
          BX    desired allocation strategy code (see below).
          ──────────────────────────────────────────────────────────────────
 Returns: AX    error code if CF is set to CY
          ──────────────────────────────────────────────────────────────────
    Info: Selects the method for DOS to use in satisfying subsequent memory
          allocations (via fn 48H).  BX must be one of:

 Value Description
 ▀▀▀▀▀ ▀▀▀▀▀▀▀▀▀▀▀▀▀▀▀▀▀▀▀▀▀▀▀▀▀▀▀▀▀▀▀▀▀▀▀▀▀▀▀▀▀▀▀▀▀▀▀▀▀▀▀▀▀▀▀▀▀▀▀▀▀▀▀▀▀▀▀
 0000h FIRST_FIT_LOW      Search conventional▲ memory for the available
                          block having the lowest address.  This is the
                          default strategy.
 0001h BEST_FIT_LOW       Search conventional RAM for the available block
                          that most closely matches the requested size.
 0002h LAST_FIT_LOW       Search conventional RAM for the available block
                          having the highest address.
                          ─────────────────────────────────────── DOS 5.0+
 0080h FIRST_FIT_HIGH     Search UMB▲ memory for the available block that
                          most closely matches the requested size.  If
                          none, search conventional memory.
 0081h BEST_FIT_HIGH      Search UMB memory for the available block that
                          most closely matches the requested size.  If
                          none, search conventional memory.
 0082h LAST_FIT_HIGH      Search UMB memory for the available block having
                          the highest address.  If none, search
                          conventional memory.

 0040h FIRST_FIT_HIGHONLY Search UMB memory for the available block having
                          the lowest address.
 0041h BEST_FIT_HIGHONLY  Search UMB memory for the available block that
                          most closely matches the requested size.
 0042h LAST_FIT_HIGHONLY  Search UMB memory for the available block having
                          the highest address.

Versions: ■ Unavailable before DOS 3.0.  In 3.x-4.x, only valid codes are
            0000h, 0001h, and 0002H.  Other code valid only with DOS 5.0+.

   Notes: ■ Programs which change the allocation strategy should use fn
            5800H and save the current setting and be sure to change it
            back (via this fn) before terminating.

          ■ If the upper memory link has not been set (see fn 5803H), then
            all allocations will be in conventional▲ memory.

          ■ When a program is loaded high via loadhigh, its code will be in
            upper memory, but additional allocations will be made according
            to the current allocation strategy (you must set it yourself).

See Also: Accessing Upper Memory
          Memory Control Functions
          DOS Functions
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