Function Calls; Categories Of Calls; Error Codes - Tandy 1000 Programmer's Reference Manual

Chapter 1 I System
Calls
Function Calls
Categories of Calls
The MS-DOS function calls are divided into 2 groups: old
and new. The old calls, Functions O O H through 2EH, are
included in this version of MS-DOS to provide compatibil-
ity with earlier versions. The new calls, Functions 2FH
through 57H, should be used in new programs instead of
the old calls wherever possible. Programs that use the new
calls cannot be run on earlier versions of MS-DOS.
The function
categories:
00H-12H
13H-24H
25H-26H
27H-29H
2AH-2EH
2FH-38H
39H-3BH
3CH-46H
47H
4CH-4FH
48H-4BH
54H-57H
calls can be divided into the following
Old character device I/O
Old file management
Old non-device functions
Old file management
Old non-device functions
New function group
Directory group
New file management group
Directory group
New memory management group
New function group
New function group
Error Codes
Many of the function calls in the new group (2FH-57H)
return with the carry flag reset if the operation was suc-
cessful. If the carry flag is set, then an error occurred
and register AX contains the binary error return code.
These codes are as follows:
25