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Friday, November 3, 2023

The Zilog Z80 microprocessor

© Mark Ollig


In 1969, Intel was asked to develop customized chips for the Busicom 141-PF printing calculator manufactured by Japan’s Nippon Calculating Machine Corp.

In 1971, Intel Corp. engineers produced the 4004-computing silicon chip used in the Busicom 141-PF.

The Intel 4004 is the first microprocessor produced for commercial use.

A microprocessor is a small integrated circuit that combines data processing and control functions for executing instructions and performing calculations.

The Intel 4004 was the first single-chip integrated circuit (IC) microprocessor to combine all processing components into a single chip.

IC chips are small semiconductor materials that contain electronic circuit components such as transistors, resistors, and capacitors.

By integrating these components, ICs can deliver high-speed, compact, cost-effective circuits while ensuring optimal performance.

ICs have revolutionized the electronics industry by enabling the design of smaller and more powerful electronic devices.

The Intel 4004 microprocessor has a four-bit (known as a nibble in binary) architecture and is an integrated circuit chip with a clock speed of 740 kHz.

The on-chip oscillator circuit generated the clock signal using an external quartz crystal to maintain a stable frequency.

The microprocessor could execute 92,000 basic operations in one second. These operations could include arithmetic calculations, data transfers, and logical comparisons.

The microprocessor used 2,300 transistors and had a 16-pin DIP (dual in-line package) plugged into a rectangular socket with two rows of eight pins soldered to the electronic circuit board.

Four individuals were responsible for the creation of the Intel 4004 microprocessor.

Federico Faggin designed the Intel 4004, while Marcian E. Hoff was responsible for the architecture and development of the instruction set. Stan Mazor created the software, and Masatoshi Shima collaborated with Intel during the microprocessor’s development.

The Intel 4004 consolidates all the essential components required to operate a computer, including the central processing unit, memory, and input/output controls, onto a single chip made of silicon.

The Intel 4004 was the first programmable microprocessor available for purchase. With them, engineers could customize software for various electronic devices.

The Intel 4004 US Patent is No. 3,821,715.

During the 1970s, microprocessors revolutionized electronic technology and paved the way for the development of today’s digital computing systems.

The Intel 4004 was integrated into electronic devices such as automated tellers, cash machines, the Wang 1222-word processor, Bally Flicker pinball and Bally Alley arcade bowling machines, and others.

In 1974, Federico Faggin, Ralph Ungermann, and Masatoshi Shima founded Zilog, Inc., known for producing microprocessors, microcontrollers, and other integrated circuits.

The company developed the Zilog Z80 microprocessor, which hit the market in 1976, followed by the Z80A.

Computers such as the Osborne I, KayPro II, Sinclair ZX-80, ZX-81, ZX Spectrum, and the popular Radio Shack TRS-80 used the Z80 microprocessors.

The Z80A microprocessor had an eight-bit data bus, used a 40-pin ceramic side-brazed DIP package, and required a five-volt power supply, a current draw of 90mA, and a maximum clock speed of 4 MHz. It also supported a physical memory of up to 64 KB.

The Zilog Z80/A processors were used in eight-bit CPUs that ran the Control Program for Microcomputers (CP/M) operating system. The Intel 8080, released in 1974, was also used with the CP/M.

The Z80A was also used in video game consoles and early arcade games such as Pac-Man and medical, telecommunications, and networking equipment.

In 1989, Zilog was acquired by a group of investors and then by Texas Pacific Group in 1998.

Zilog has continued to produce eight-bit microcontrollers since 2007.

In 2009, IXYS Corp. acquired Zilog, a company based in Milpitas, CA, and redirected its attention toward the industrial and consumer markets for electronic components used in motion detection, motor controlling, wireless, and security applications.

In 2017, Zilog and IXYS Corp. were acquired by Littelfuse Inc., an American electronic manufacturing company based in Chicago.

Zilog provides 8-bit and 32-bit microprocessors and customized system-on-chip solutions for automotive and industrial control systems, home appliances, consumer electronics, wireless communication, and security devices.

Today, you can purchase the Texas Instruments TI-84 Plus Graphing Calculator, which uses the Zilog eZ80 8-bit microprocessor (introduced in 2001) with a clock speed of 48 MHz.

According to the much-referred UserBenchmark website, the AMD EPYC 9754 ‘Bergamo’ and the AMD Ryzen 9 7950X3D are recognized as the fastest processors in 2023. 

The Intel Core i9-14900K and the AMD Ryzen 9 7945HX are also mentioned.

I wrote today’s column using my HP Laptop 17-cn3, powered by the Intel Core i7-1355U processor and running the 64-bit Microsoft Windows 11 Home operating system.

Zilog’s success with the Z80 microprocessor contributed to establishing California’s Silicon Valley as a hub for technology innovation. 

From my collection of stuff, I found a Zilog Z80A SIO/1 (Serial Input/Output Controller/single-channel device) 4 MHz 40 Pin DIP microprocessor and took a photo to feature in today’s column.