CONFIG_ALPHA_EB66 is not available for thedefaultarchitecture x86.
Result is shown for architecture alpha

EB66

modulename: sys_eb64p.ko

configname: CONFIG_ALPHA_EB66

Alpha system type
└─>EB66
In linux kernel since version 2.6.12  
A Digital DS group board. Uses 21066 or 21066A. I/O sub-system is
identical to EB64+. Baby PC-AT size. Runs from standard PC power
supply. The EB66 schematic was published as a marketing poster
advertising the 21066 as "the first microprocessor in the world with
embedded PCI".

source code: