Slot A refers to the physical and electrical specification for a 242-lead single-edge-connector used by early versions of AMD's Athlon

Athlon

Athlon is the brand name applied to a series of x86-compatible microprocessors designed and manufactured by Advanced Micro Devices . The original Athlon was the first seventh-generation x86 processor and, in a first, retained the initial performance lead it had over Intel's competing processors...

 processor.

The Slot A connector allows for a higher bus rate than Socket 7

Socket 7

Socket 7 is a physical and electrical specification for an x86-style CPU socket on a personal computer motherboard. The socket supersedes the earlier Socket 5, and accepts P5 Pentium microprocessors manufactured by Intel, as well as compatibles made by Cyrix/IBM, AMD, IDT and others.Socket 7 was...

 or Super Socket 7

Super Socket 7

The Super Socket 7, also referred to as Super 7, is an extension of the Socket 7 ZIF socket specification. It features a 100 MHz front-side bus, support for AGP, and a SPGA package. Super Socket was used by AMD K6-2 and K6-III processors, and some of the final Cyrix M-II processors...

. Slot A motherboards use the EV6 bus protocol, a technology originally developed by Digital Equipment Corporation

Digital Equipment Corporation

Digital Equipment Corporation was a major American company in the computer industry and a leading vendor of computer systems, software and peripherals from the 1960s to the 1990s...

 (DEC) for its Alpha 21264

Alpha 21264

The Alpha 21264 was a Digital Equipment Corporation RISC microprocessor introduced in October, 1996. The 21264 implemented the Alpha instruction set architecture .- Description :...

 microprocessor.

Slot A is mechanically compatible but electrically incompatible with Intel's Slot 1

Slot 1

Slot 1 refers to the physical and electrical specification for the connector used by some of Intel's microprocessors, including the Pentium Pro, Celeron, Pentium II and the Pentium III...

. As a consequence, Slot A motherboards were designed to have the connector's installed orientation be rotated 180 degrees relative to Slot 1 motherboards to discourage accidental insertion of a Slot 1 processor into a Slot A motherboard, and vice versa. The choice to use the same mechanical connector as the Intel Slot 1 also allowed motherboard manufacturers to keep costs down by stocking the same part for both Slot 1 and Slot A assemblies.

Slot A was superseded by Socket A

Socket A

Socket A is the CPU socket used for AMD processors ranging from the Athlon Thunderbird to the Athlon XP/MP 3200+, and AMD budget processors including the Duron and Sempron. Socket A also supports AMD Geode NX embedded processors...

.