What is CISC architecture or CISC chips?
ClSC (pronounced "sisk") stands for complex instruction set computing. A CISC chip is a microprocessor that
has a large set of instructions that are built into its microcode so it
can carry out most computations directly. Compare CISC chips with RISC chips, which recognize fewer instructions. CISC term applied to all the older computer
ARCHITECTURES to distinguish them from the new RISC designs introduced
in the 1990s. RISC (reduced instruction set computing) technology is
touted as faster than CISC and is increasingly common, although there is
a great deal of debate over the pros and cons of each type of
architecture.
A
CISC INSTRUCTION SET contains instructions that perform several steps
in one, and therefore take many CYCLES to execute - such as the Intel
8086's ADC instruction, which takes more than 20 cycles to add the
contents of a REGISTER to a memory
location. The concept grew through the early days of computing from a
desire to make life easier for MACHINE CODE programmers, but now that
most programming is done in HIGH-LEVEL languages it is less necessary
and hinders hardware efficiency. RISC designs employ a larger number of
simple, one cycle operations that are automatically generated by a
COMPILER.
Chapter : Introduction to Computer
- Computer Fundamental
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