WAIT¶
Implementation Note¶
⚠️ Not Implemented: This statement is parsed for compatibility but performs no operation.
Behavior: The WAIT statement parses successfully without errors, but does not perform any hardware I/O operations (it is silently ignored).
Why: This feature requires direct hardware I/O port access, which cannot be provided by a Python-based interpreter. WAIT was historically used to synchronize with hardware devices by polling I/O ports, which is not possible in modern cross-platform software.
Limitations: All WAIT statements are silently ignored. The program continues immediately to the next statement without any delay or hardware polling.
Alternative: For delays, use a busy loop with a counter. For event synchronization, restructure the program to use sequential logic instead of hardware polling.
Historical Reference: The documentation below is preserved from the original MBASIC 5.21 manual for historical reference.
Syntax¶
Where: - port number: Integer expression specifying the I/O port to monitor - I: Integer expression for AND mask - J: Optional integer expression for XOR mask (default: 0)
Purpose¶
To suspend program execution while monitoring the status of a machine input port.
Remarks¶
The WAIT statement causes execution to be suspended until a specified machine input port develops a specified bit pattern. The data read at the port is exclusive ORed with the integer expression J, and then ANDed with I. If the result is zero, BASIC-80 loops back and reads the data at the port again. If the result is nonzero, execution continues with the next statement. If J is omitted, it is assumed to be zero.
CAUTION: It is possible to enter an infinite loop with the WAIT statement, in which case it will be necessary to manually restart the machine.