Introduction to Programming Message Queues
20 Agilent 8163A/B, 8164A/B & 8166A/B Mainframes, Fifth Edition
How the Input Queue Works
The input queue is a FIFO queue (first-in first-out). Incoming bytes are
stored in the input queue as follows:
1 Receiving a byte:
• Clears the output queue.
• Clears Bit 7 (MSB).
2 No modification is made inside strings or binary blocks. Outside strings
and binary blocks, the following modifications are made:
• Lower-case characters are converted to upper-case.
• The characters 00
16
to 09
16
and 0B
16
to 1F
16
are converted to spaces
(20
16
).
• Two or more blanks are truncated to one.
3 An EOI (End Or Identify) sent with any character is put into the input
queue as the character followed by a line feed (LF, 0A
16
). If EOI is sent
with a LF, only one LF is put into the input queue.
4 The parser starts if the LF character is received or if the input queue is
full.
Clearing the Input Queue
Switching the power off, or sending a Device Interface Clear signal, causes
commands that are in the input queue, but have not been executed to be
lost.
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