INT 21,26 - Create New Program Segment Prefix

	AH = 26h
	DX = segment address of new PSP

	returns nothing

	- allocates memory for a PSP and copies current PSP there
	- used before DOS 2.x to spawn a child process
	- the application is responsible for allocating any memory
	  necessary for the child process
	- INT 21,4B (EXEC) is now the recommended method for starting
	  a child process, so this function should be avoided

	- see also INT 21,55