Tandy 1000 Programmer's Reference Manual page 110

Chapter 1 I System Calls
Open
Open a File
Function Call 3DH
Opens a file. The following values are allowed for the
ac-
cess code:
0
-
The file is opened for reading.
1
-
The file is opened for writing.
2
-
The file is opened for both reading and writing.
The readiwrite pointer is set at the first byte of the file
and the record size of the file is 1 byte. The returned
file handle must be used for subsequent IiO to the file.
Entry Conditions:
AH
=
3DH
DS:DX
=
pointer to ASCIIZ pathname for file to open
AL
=
access code (0
=
read, 1
=
write, 2
=
read
and
Exit Conditions:
Carry set:
Carry not set:
Error Returns:
AX
=
12
write)
AX
=
error code
AX
=
file handle number
Invalid access. The access specified in AL was not in
the range 0-2.
File not found. The path specified was invalid or not
found.
Access denied. The user attempted to open a directory
or volume
ID,
or open a read-only file for writing.
Too many open files. There were no free handles
available in the current process or the internal sys-
tem tables were full.
AX
=
2
AX
=
5
AX
=
4
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