An FPSC is an abbreviation of a Field Programmable System on a Chip. In
essence, it is the perfected combination of an FPGA with a dedicated ASIC
core. First invented by Lucent Technologies; Agere Systems took the
business when they split, finally selling the business and all patents to
Lattice Semiconductor.
The basic idea is that FPGA gates are relatively slow, but amazingly
re-configurable. ASIC gates are much, much faster, but are hard programmed. i.e.
they cannot be changed.
So, conceptually, if you take the things that are fixed in a design, such as
a complex MUX, and add that to an array of FPGA gates, you give the user the
benefit of fast ASIC circuitry, along with lots of FPGA gates behind it.
Many companies, such as Xilinx and Altera have conceptual FPSC's (under a
different name to avoid patent infringement) - it seems to be the way the market
is moving.
For more info visit: http://www.latticesemi.com/products/fpsc/index.cfm