Tandy 1000 Programmer's Reference Manual page 122

Chapter 1 I System Calls
Duplicate a File Handle
Function Call 45H
Takes an already opened file handle and returns a new handle
that refers to the same file a t the same position.
Entry Conditions:
AH
=
45H
BX
=
file handle to duplicate
E xi t Conditions
:
Carry set:
Carry not set:
Error Returns:
AX
=
6
AX
=
error code
AX
=
new file handle
Invalid Handle. The handle passed in BX is not cur-
rently open.
Too many open files. There were no free handles
available in the current process or the internal system
tables were full.
AX
=
4
Example:
DUP e q u
4 5 H
mov
b x , h a n d l e
mov a h , D u p
i n t
21 H
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