Note: This API call is for DOS personality only. Use Family API for portability.
Int 21H, AH=31H
2 and higher
TERMINATE AND STAY RESIDENT
AH = 31h AL = return code DX = number of paragraphs to keep resident
the value in DX only affects the memory block containing the PSP; additional memory allocated via AH=48h is not affected the minimum number of paragraphs which will remain resident is 11h for DOS 2.x and 06h for DOS 3.0+ most TSRs can save some memory by releasing their environment block before terminating (see #01378 at AH=26h,AH=49h) any open files remain open, so one should close any files which will not be used before going resident; to access a file which is left open from the TSR, one must switch PSP segments first (see AH=50h)
AH=00h,AH=4Ch,AH=4Dh,INT 20,INT 22,INT 27
Text based on Ralf Brown Interrupt List Release 61