Intel 8080
The Intel 8080, introduced in April 1974, was the 8-bit microprocessor that turned the microprocessor from a promising component into the foundation of an industry, because it was the first one fast and practical enough that people built general-purpose computers around it in volume. It ran at 2 MHz, addressed 64 KB of memory, required far less awkward support circuitry than the 8008 it descended from, and offered a richer, more usable instruction set. Those improvements sound incremental, but together they crossed the threshold where building a real computer around the chip became a reasonable engineering proposition rather than a struggle against the part's limitations.
The 8080 was designed by Federico Faggin, Masatoshi Shima, and colleagues explicitly to fix the 8008's practical problems, and that repair-oriented design is why it succeeded where its predecessor stalled. The 8008 had needed many support chips and ran slowly; the 8080 reduced the surrounding part count, raised the clock substantially, added instructions and addressing that made programming more natural, and used a more convenient power and bus arrangement. It retained enough conceptual continuity with the 8008 that existing knowledge and some software carried forward, so it inherited an ecosystem while removing the friction that had limited it. The design was good enough that Faggin soon left Intel to found Zilog and build an enhanced, compatible successor, the Z80.
The 8080's defining moment was the MITS Altair 8800 of 1975, the kit computer that is widely credited with igniting the personal-computer hobbyist movement. The Altair put an 8080 at the center of an affordable build-it-yourself machine, and the enthusiast community that formed around it — writing software, designing expansion cards, and standardizing a bus — became the substrate from which the early personal-computer industry grew. It was for the Altair that a young Bill Gates and Paul Allen wrote a BASIC interpreter, the product that launched Microsoft, which is one concrete illustration of how much downstream activity the 8080 seeded.
The 8080 also anchored CP/M, and the pairing of a popular CPU with a portable operating system is what made an 8-bit software market possible. Gary Kildall's CP/M, written to run on the 8080, gave the many different 8080-based machines a common software environment, so an application written for CP/M could run across a range of hardware rather than being tied to one manufacturer's design. This decoupling of software from specific hardware — program to the operating system, not to the machine — is a pattern that would define the whole personal-computer business, and the 8080 plus CP/M is where it first took hold at scale.
The 8080's architecture flowed directly into Intel's later dominance through the 8086 and the x86 line. When Intel built the 16-bit 8086 in 1978, it deliberately kept the design close enough to the 8080 that 8080 software could be translated across with relative ease, preserving the accumulated ecosystem. That continuity is a recurring theme in the industry: Intel repeatedly chose compatibility with its installed base over a clean break, and the 8080 is the early link in that chain, which is why its influence is visible in processors built decades later.
Read the Intel 8080 as the chip that crossed the usability threshold: the first microprocessor good enough to build real computers around in quantity, whose pairing with the Altair and CP/M created the hardware community and the portable-software habit the personal-computer industry was then built on.