integrated circuit An integrated circuit (IC), also known as a microchip or simply chip, is a set of electronic circuits, consisting of various electronic components (such as transistors, resistors, and capacitors) and their interconnections. These components a ...

s, the stepping level or revision level is a version number that refers to the introduction or revision of one or more

photolithographic Photolithography (also known as optical lithography) is a process used in the manufacturing of integrated circuits. It involves using light to transfer a pattern onto a substrate, typically a silicon wafer. The process begins with a photosensit ...

photomask A photomask (also simply called a mask) is an opaque plate with transparent areas that allow light to shine through in a defined pattern. Photomasks are commonly used in photolithography for the production of integrated circuits (ICs or "chips") ...

s within the set of photomasks that is used to pattern an integrated circuit. The term originated from the name of the equipment ( "steppers") that exposes the

photoresist A photoresist (also known simply as a resist) is a light-sensitive material used in several processes, such as photolithography and photoengraving, to form a patterned coating on a surface. This process is crucial in the electronics industry. T ...

to light. Integrated circuits have two primary classes of mask sets: firstly, "base" layers that are used to build the structures, such as transistors, that comprise circuit logic and, secondly, "metal" layers that connect the circuit logic. Typically, when an integrated circuit manufacturer such as Intel or AMD produces a new stepping (i.e. a revision to the masks), it is because it has found bugs in the logic, has made improvements to the design that permit faster processing, has found a way to increase yield or improve the "bin splits" (i.e. create faster transistors and thus faster CPUs), has improved maneuverability to more easily identify marginal circuits, or has reduced the circuit testing time, which can in turn reduce the cost of testing. Many integrated circuits allow interrogation to reveal information about their features, including stepping level. For example, executing

CPUID In the x86 architecture, the CPUID instruction (identified by a CPUID opcode) is a processor supplementary instruction (its name derived from " CPU Identification") allowing software to discover details of the processor. It was introduced by Int ...

instruction with the EAX register set to '1' on

x86 x86 (also known as 80x86 or the 8086 family) is a family of complex instruction set computer (CISC) instruction set architectures initially developed by Intel, based on the 8086 microprocessor and its 8-bit-external-bus variant, the 8088. Th ...

CPUs will result in values being placed in other registers that show the CPU's stepping level. Stepping identifiers commonly comprise a letter followed by a number, for example ''B2''. Usually, the letter indicates the revision level of a CPU's base layers and the number indicates the revision level of the metal layers. A change of letter indicates a change to both the base layer mask revision and metal layers whereas a change in the number indicates a change in the metal layer mask revision only. This is analogous to the major/minor revision numbers in

software versioning Software versioning is the process of assigning either unique ''version names'' or unique ''version numbers'' to unique states of computer software. Within a given version number category (e.g., major or minor), these numbers are generally assig ...

. Base layer revision changes are time consuming and more expensive for the manufacturer, but some fixes are difficult or impossible to accomplish with metal-only changes. The Intel Core microarchitecture uses a number of steppings, which unlike prior microarchitectures not only represent incremental improvements but also changes to features, such as a different cache size or the addition of low-power modes. Most of these steppings are used across brands, typically involving features being disabled or clock frequencies being reduced on low-end chips. Steppings with a reduced cache size use a separate naming scheme, which means that CPU steppings are not necessarily released in alphabetic order of stepping.

References

Integrated circuits Version control Central processing unit {{microcompu-stub