I  IBM Personal Computers
      C. Disk Operating System
         3. Function Call
	    a) Groups
	call group	description
	----------	-----------------------------------------------
	00h             program terminate 
	01h-0Ch         character device I/O, CP/M compatibility format 
	0Dh-24h         file management,      CP/M compatibility format 
	25h-26h         nondevice functions,  CP/M compatibility format 
	27h-29h         file management,      CP/M compatibility format 
	2Ah-2Eh         nondevice functions,  CP/M compatibility format 
	2Fh-38h         extended functions 
	39h-3Bh         directory group 
	3Ch-46h         extended file management 
	47h             directory group 
	48h-4Bh         extended memory management 
	54h-57h         extended functions 
	5Eh-5Fh         networking 
	60h-62h         extended functions 
	63h-66h         enhanced foreign language support