An Introduction to the CMS EMU DDU
or
Where the data from the Motherboard Goes
Device Dependent Unit (DDU)
-
Interface point: detector components <-> Event Builder
(EB)
-
Transparent link: EMU Motherboard (MB) -> DDU Driver software.
-
DDU uses 32-bit (DWORD), 33 MHz PCI Bus (Burst to 132 MB/s
= 66 MWORD/s)
-
66-MHz and/or 64-bit PCI not readily available
Limitations from the DDU:
-
32-bit PCI bus -> 16-bit WORD data
-
One of the 16 bits is reserved for control flag
-
lack of unique marker word(s)
Conclusion:
This slight inconvenience and additional overhead should
be considered acceptable given the goals of the EMU system, and indeed
the CMS detector, as a whole.
P. Nylander,nylander@mps.no_.-more-._spam.ohio-state.edu
23 January 1999