DCB depopulation
VTTx depopulation
As the backplanes depopulate, for some DCBs only some GBTxs are used. The backplane design rules specify that when GBTxs are unused the unused GBTxs are always GBTx4 and GBTx5. For these boards the optical mezzanine for GBTx4-5 does not need to be installed, in addition to (entire) DCB boards' depopulation.
Note
I do not believe any special jumpers need to be installed but I will verify this (Will).
DCB placement with depopulated VTTx
The backplane mapping specifies which pairs of GBTxs are unused in the detector. They can be translated from "proto" JD slots to True and Mirror JD slots with the following table1:
| Proto | 0 | 1 | 2 | 3 | 4 | 5 | 6 | 7 | 8 | 9 | 10 | 11 |
|---|---|---|---|---|---|---|---|---|---|---|---|---|
| True | 0 | 4 | 2 | 3 | 1 | 5 | 6 | 8 | 7 | 9 | 10 | 11 |
| Mirror | 4 | 0 | 3 | 2 | 5 | 1 | 8 | 6 | 9 | 7 | 11 | 10 |
- Full backplane: This backplane has no depopulated DCBs
- Partially depopulated backplane:
JDslots1, 5, 6, 8should have DCBs with depopulated VTTx. This applies to both True and Mirror backplanes. - Depopulated backplane: In addition to
JD 1, 5, 6, 8, slots7, 9should also DCBs with depopulated VTTx. This applies to both True and Mirror backplanes.
The total number of DCBs with depopulated VTTx is 72:
12 P backplanes * 4 DCBs + 4 D backplanes * 6 DCBs
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Copied from Zishuo's notes on mapping. ↩