INTEL 4040

General description

The Intel 4040, an enhancement of the Intel 4004, debuted in 1974 as a 4-bit microprocessor. With around 3,000 transistors and an improved instruction set, it offered higher performance and greater versatility. Its clock speed of up to 740 kHz made it suitable for various applications. While it didn’t achieve the same landmark status as the 4004, the 4040 found a niche in calculators, industrial control systems, and early microcomputer systems. Its incremental improvements laid the groundwork for subsequent microprocessor generations, contributing to the ongoing evolution of integrated circuit technology.

  • Functionally and Electrically Upward Compatible to 4004 CPU
  • 14 Additional Instructions (60 total) Including Logical Operations and Read Program Memory
  • Interrupt Capability
  • Single Step Operation
  • 8K Byte Memory Addressing Capability
  • 24 Index Registers
  • Subroutine Nesting to 7 Levels
  • Standard Operating Temperature Range of 0°to 70°C
  • Also Available With -40°to +85° C Operating Range

The Intel® 4040 is a complete 4-bit parallel central processing unit (CPU). The CPU can directly address 4K eight bit instruction words or 8K with a bank switch. Seven levels of subroutine nesting, including interrupt, and 24 randomly accessable index registers (24×4) are provided as convenient facilities for the designer. The index registers may be used for addressing or for scratch pad memory for storing computation results. The interrupt feature permits a normal program sequence to be interrupted, with normal program execution continuing after the interrupt service routine is completed. Provisions have also been made to permit single-stepping the CPU using the STOP and ACKNOWLEDGE signals.

The 4040 is an enhanced version of the 4004 and as such retains all the functional capability of that device. It will execute all the 4004 instructions, and is also electrically compatible with all components used with a 4004 CPU.


Historical outline

The Intel 4004, unveiled in 1971, was a trailblazing microprocessor, masterminded by Federico Faggin and his team at Intel. With 2,300 transistors operating at 740 kHz, it was a marvel of miniaturization. Originally intended for calculators, the 4004 sparked a paradigm shift by enabling programmability in electronic devices.

The Intel 4004’s historical narrative intertwines with the Busicom calculator story. In the early 1970s, Busicom, a Japanese calculator manufacturer, collaborated with Intel to create a custom microprocessor for their calculators. However, Intel engineer Federico Faggin proposed a more versatile microprocessor design, leading to the birth of the 4004.

Although the collaboration with Busicom ended after the 4004’s design shifted to a more general-purpose architecture, the initial partnership played a crucial role. Busicom’s requirements influenced the microprocessor’s core features, while Intel’s innovation transformed the design into a groundbreaking chip that revolutionized the electronics industry.

The Busicom connection underscores how unexpected turns in technology partnerships can lead to transformative breakthroughs. The convergence of Busicom’s needs and Intel’s vision resulted in the birth of the 4004, an event that not only altered the trajectory of computing but also set the stage for the microprocessor’s expansive journey through history.

As the first commercially available microprocessor, the 4004 was a watershed moment in computing history, initiating the microcomputer revolution. Its success spurred the development of the MCS-4 family of microprocessors, driving innovation in diverse industries. Its introduction marked the transition from specialized hardware to general-purpose computation, democratizing access to computing power.

The 4004’s compact architecture and versatility ignited the personal computer era, transforming how people interact with technology. Its profound impact transcended its time, shaping the trajectory of electronics, telecommunications, and beyond. The 4004’s influence is imprinted on the DNA of modern devices, underscoring its enduring legacy as the cornerstone of the digital age and a testament to human ingenuity in the pursuit of technological progress.

Emulation and Development Tools

The Intel 4040 microprocessor was supported by hardware tools like the Intellec-4 MOD 40, that facilitated development and testing of software for systems based on the 4040 microprocessor.
  • The Intel Intellec 4 MOD 40 was a development system tailored for the Intel 4040 microprocessor, introduced in the mid-1970s. It provided essential tools for software development, debugging, and testing of systems based on the Intel 4040 architecture. Equipped with a hexadecimal keypad and LED display, the Intellec 4 allowed programmers to manually input machine code and monitor the processor’s behavior.The Intellec 4’s software suite included a monitor program, assembler, and simulator, enabling efficient software development. Its simulator allowed testing without physical hardware. This development system played a crucial role in bridging the gap between hardware and software, making it easier for developers to harness the capabilities of the Intel 4040 microprocessor.

Applications for the 4004 Processor

The Intel 4040 microprocessor, introduced in 1974, found applications in diverse fields despite its limited capabilities. It powered early embedded systems like industrial control devices, enhancing automation processes. Additionally, the 4040 played a role in calculators, offering basic arithmetic operations. Its utilization extended to early microcomputer systems, aiding in data processing and control tasks.

While not as revolutionary as subsequent microprocessors, the Intel 4040 laid the foundation for the integration of computing into various industries. Its impact was seen in a range of devices, from factory automation to rudimentary data processing, showcasing its adaptability and influence during the nascent stages of microprocessor technology.

  • The MC404 (Microcomputing System MCS-4 and MCS-40) is now developed on the original integrated circuits from the seventies. The MC404 was designed as a development platform for learning and experimenting with first microprocessors. It was built around the Intel 4004 and Intel 4040 microprocessors.The MC404 featured a 24-key keypad for input, a  LED display for output. It came with a calculator program in ROM, which allowed users to check the Intel 4004 processor in action.