RISC and CISC

Various types of technology have been used  to speed up computer processing time; RISC and
CISC are examples of this technology. With the advancement of semiconductor technology, the
integration density of integrated circuits has risen continually. At present, computers are made
with integrated circuits, and RISC and CISC are the two approaches for developing computers.
Computers configured for high speed with simple instructions and simplified hardware are
called RISCs. In contrast, those where complicated instructions are configured on one circuit
are called CISCs.  

RISC (Reduced Instruction Set Computer)

These computers have only a set of simple, frequently used instructions integrated onto a single
VLSI (very large scale integration) chip in order to achieve high performance through improved machine cycles (operation speed) and a reduction in instruction processing time. The emphasis is placed on keeping the length of each instruction to a fixed length and limiting the time required to execute each instruction to  a fixed amount. By doing so, the technology of pipeline control has been easily implemented. However, the number of instructions to be executed becomes large unless efficient object programs are created, so it is essential that the compiler have an optimization function.
Most computers called workstations are of this type.  

CISC (Complex Instruction Set Computer)

These computers have complex instructions integrated onto a single VLSI ship in order to achieve high overall performance. Most general-purpose computers are CISCs.