(EPIC also stand for Electronic Privacy Information Center.)
EPIC (Explicitly Parallel Instruction Computing) is a 64-bit microprocessor instruction set, jointly defined and designed by Hewlett Packard and Intel, that provides up to 128 general and floating point unit registers and uses speculative loading, predication, and explicit parallelism to accomplish its computing tasks. By comparison, current 32-bit CISC and RISC microprocessor architectures depend on 32-bit registers, branch prediction, memory latency, and implicit parallelism, which are considered a less efficient approach in microarchitecture design.
IA-64 (Intel Architecture-64), Intel's first 64-bit CPU microarchitecture, is based on EPIC. Intel's first implementation, long expected and well-known as Merced (its code name), was christened with the Itanium brand name in October, 1999. It is expected that Itanium-based systems will be compatible with versions of existing and future operating systems including HP-UX, 64-bit Windows, IA-64 Linux, Project Monterey, and Novell Modesto.