Cal Trig Readout via AONM Cards

                                                   Original: 27-APR-1999 
                                                     Latest: 27-APR-1999 

The information to be readout from the Calorimeter Trigger includes:

	o Global EM Et					24 bits
	o Global H Et					24 bits
	o Global Et					24 bits

	o Counts of towers above reference
	  (8, 11 bit counts				88 bits?)
	  4 threshold comparisons on each count*	32 bits -> 10 FPGAs

	o Global Et threshold comparisons*		< 16 bits -> 5 FPGAs
	o Px						24 bits
	o Py						24 bits
	o MPt						8 bits
	  plus 8 bits of threshold comparisons*		8 bits -> 3 FPGAs

	o Large tiles
	  6 bits for counts for each reference set	48 bits
	  3 count thresholds per reference set		24 bits

Items marked with a * must also be available as outputs on the front
panel since they are required as AOIT.  Each set of 16 AOIT must be
accompanied by a gap and a strobe signal.  Recall that an AONM card
can handle 128 inputs but that each MSA FPGA can produce at most 4 MSA
Outputs.  Nonetheless, the above 4 groups could be neatly handled by 4
AONM cards.

It may be possible to accomodate all of this readout with a single
FPGA design.  For example, a set of 32 inputs could be selected for
readout from a given FPGA.  (32 is a good number because we typically
like to have two 16 bit words readout per FPGA and because it
more-or-less cleanly handles the chunks of data that we know about.)
These inputs could be fed to a BXHSR and then captured for readout in
the usual manner.  The MSA Outputs could be a selectable subset of the
32 inputs or the gap and strobe signals.

Timing Signals
--------------

1. the equivalent of the Tick Clock to capture the data and to shift it
   through the BXHSR

2. a gap signal

3. a strobe signal

4. Capture HSRO Data

5. Capture Monitor Data

6. Transport HSRO Data