INT 21,49 - Free Allocated Memory
AH = 49h
ES = segment of the block to be returned (MCB + 1para)
on return:
AX = error code if CF set (see DOS ERROR CODES)
- releases memory and MCB allocated by INT 21,48
- may cause unpredictable results is memory wasn't allocated using
INT 21,48 or if memory wasn't allocated by the current process
- checks for valid MCB id, but does NOT check for process ownership
- care must be taken when freeing the memory of another process, to
assure the segment isn't in use by a TSR or ISR
- this function is unreliable in a TSR once resident, since
COMMAND.COM and many other .COM files take all available memory
when they load
- see INT 21,4A