Atari 400

184 User's Handbook to the Atari 400/ 800 Computers
Illustration 5-2. USR Hardware Stack
Top of Stack
Bottom of Stack
XIO
USR Argument Count
First USR Argument
Second USR Argument
Final USR Argument
BASIC Program's
Return Address
Stack Contents Prior
to USR
EXAMPLE
050 DIM A$(50)
100
A$ = "57 A72B"
200 PRINT VAL(A$)
300 PRINT VAL(A$) + 2
RUN
57
59
The XIO statement is a generalized in put/output statement
which can perform a wide range of input and output operations.
These operations are summarized in Table 5-4.