In processor design, microcode serves as an intermediary layer situated between the central processing unit (CPU) hardware and the programmer-visible instruction set architecture of … See more

Instruction sets
At the hardware level, processors contain a number of separate areas of circuity, or "units", that perform … See more

Early examples
In 1947, the design of the MIT Whirlwind introduced the concept of a control store as a way to simplify … See more

Each microinstruction in a microprogram provides the bits that control the functional elements that internally compose a CPU. The advantage over a hard-wired CPU is that internal CPU control becomes a specialized form of a computer program. Microcode thus … See more

Microcode was originally developed as a simpler method of developing the control logic for a computer. Initially, CPU instruction sets See more

• The Analytical engine envisioned by Charles Babbage uses pegs inserted into rotating drums to store its internal procedures.
• The See more

A few computers were built using writable microcode. In this design, rather than storing the microcode in ROM or hard-wired logic, the microcode is stored in a RAM called a … See more