No.	Function		No.	Function
System Services
0	Terminate Program
12	Get system version
Serial Services			File Services
1	Console Read byte		15	Open File
2	Console Write byte		16	Close File
3	Reader Read byte		17	Search for First file match
4	Punch Write byte		18	Search for Next file match
5	List Write byte		19	Delete File
6	Direct Console Read/Write		22	Make and Open a new file
7	Get IOBYTE		23	Rename File
8	Set IOBYTE		30	Set File Attributes
9	Console Write string		32	Set/Get User Code area
10	Read Console Buffer
11	Get Console Status
File I/O Services			Disk Services
20	File Sequential Read		13	Reset Disk System
21	File Sequential Write		14	Select Disk
26	Set file transfer buffer address		24	Get active drive map
33	File Read Random		25	Get default drive number
34	File Write Random		27	Get allocation vector
35	Compute File Size		28	Write Protect Disk
36	Set Random Record		29	Get Addr(Disk Parms)
40	Write Random with zero fill		31	Get Active Disk DPB
			37	Reset Drive

References :

MicroVibe CP/M 2.2 BDOS Overview

The Unofficial CP/M Website, CP/M Operating System Manual, CP/M 2 System Interface