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