Marathon Computer UNIPRO V3.5 - Manual (Page 182)

Maintenance and Troubleshooting
Unipro 3.5
Rev. 8.00
November 30, 1995
Software ever has the chance to "see" them. Therefore, the
alarms had to be passed on to the Host Software even if they
were already acknowledged and/or corrected. The Alarm
Queue was created to meet this need.
The Alarm Queue works on a READ & CLEAR basis.
If the Alarm Queue is read with the "x" parameter FF (Hex),
the storage location will return a word comprised of a HI byte
and a LO byte. The LO byte is the first alarm appearing in
memory while the HI byte is the second alarm appearing in
memory (thus creating the FIFO effect). If both bytes are
non-zero, then the Host will look again to see if any non-zero
values have been stored. Once the bytes are read from the
Queue, they are cleared out of the memory block.
If there is no Host Software used, the Alarm Queue is
never read, but the Queue is still written to by the instrument.
Once the Queue is filled, it cannot be written to until a location
has been cleared. Considering the fact that Host Software is
not used, the Queue will never be cleared and will never store
any of the alarms that occur after the Queue has been filled.
This does not cause a problem considering the fact that the
Queue is only used with Host Software and if the software is
not used, we do not care if it is filled or not.