ROAD word format

Each SVX road is transmitted as a single word packet from the Associative Memory Sequencer (AMS) to the Hit Buffer (HB).
The HB then sends roads to the Track Fitter (TF) putting in a single packet all hits that belong to a road togheter with the road itself. See Road_Hit packet description.

Word structure

24 23 22 21 20 19 18 17 16 15 14 13 12 11 10 9 8 7 6 5 4 3 2 1 0
HD DS 0 1 PHI(4) Road(17)

Data field assignement:

PHI SVT PHI sector (wedge) in the 0..11 range

The road address itself is the address of a specific pattern inside one AMchip. While 17 bits are allocated here for a Road Address, the present SVT Associative Memory system (AMS + AMB) can only handle up to 16 bits, for a maximum of 64k patterns per wedge. At present we only plan for 32k patterns per wedge, thus there are only 2 AMboards connected to each AMS, while the AMS can handle up to 4 boards if needed (a new backplane would be required). The leftmost bit of the road address is hardwired to 0 inside the AMS.

The pieces of the road address are:
16 15 14 13 12 11 10 9 8 7 6 5 4 3 2 1 0
0 AMB(2) AMplug(4) AMchip(3) Pattern(7)

AMBAMboard identifier in 0..3 (only 0/1 for SVT)
AMplugAMplug on that AMboard (16 AMplugs per board)
AMchipAMchip on that plug (8 chips per AMplug)
patternpattern inside that chip (128 patterns per AMchip)

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