The control-statusregister INTRPT_CTRL_STAT_REG provides control and information on the status of the control-char and NOSIGNAL and NODATA interrupts and information on the status of the counter FIFO and the VME-interrupt FIFO.
Table 6: The AORTA-R-V2 control-statusregister content (note the difference
between VME and XdBeX: because XdBeX knows no interrupt vectors the type of
interrupt has to be determined from this register)
The status of the contents of the 'interrupt' FIFOs (the 8-bit FIFO holding the VME interrupt vectors (consisting of one 2Kx8bit Cypress CY443 FIFO-chip) and the 16-bit FIFO containing the counter values (consisting of two 2Kx8bit Cypress CY443 FIFO-chips) is indicated by a set of 2 flags (F0 and F1) per FIFO-chip which can be read from the control-statusregister.
The status of the flags of the counter and interrupt vector FIFOs is an indication of the number of bytes in the FIFO, as shown in table 7.
Table 7: AORTA-R-V2 counter and VME-interrupt FIFO flags encoding.