MCS·SS Microcomputer System, Evolution

PART 2: INTRODUCTION TO MCS-85™

THE MCS·SS™ MICROCOMPUTER

SYSTEM

The basic philosophy behind the MCS·85 microcomputer system is one of logical, evolu- tionary advance in technology without the waste of discarding existing investments in hardware and software. The MCS-85 provides the existing 8080 user with an increase in per- formance, a decrease in the component count, operation from a single 5-Volt power supply, and still preserves 100% of his existing software in- vestment. For the'new microcomputer user, the MCS-85 represents the refinement of the most popular microcomputer in the industry, the Intel 8080, along with a wealth of supporting soft- ware, documentation and peripheral com- ponents to speed the cycle from prototype to production. The same development tools that Intel has produced to support the 8080 microcomputer system can be used for the MCS-85, and additional add-on features are available to optimize system development for

MCS-85~

This section of the MCS-80/85User'sManual will briefly detail the basic differences between the MCS-85 and MCS-80 families. It will illus- trate both the hardware and software compati- bilities and also reveal some of the engineering trade-ofts that were met during the design 'of the MCS-85. More detailed discussion of the MCS-85 bus operation and component specifications are available in Chapters: 2, 3, 4, and 5. The information provided in Chapter 1 will be helpful in understanding the basic con- cepts and philosophies behind the MCS-85.

EVOLUTION

In December 1971, Intel introduced the first general purpose, 8-bit microprocessor, the 8008. It was implemented in P-channel MOS technology and was packaged in a single 18 pin, dual in-line package (DIP). The 8008 used standard semiconductor ROM and RAM and, for the most part, TTL components for I/O and general interface. It immediately found applica- tions in byte-oriented end products such as ter- minals and computer peripherals where its in- struction execution (20 micro·seconds),general

	\	8080
30		~
			~	80SOA	8080A AND
			~	80SOA	8080A AND
15				"-	PERIPHERALS
15					PERIPHERALS
3					\	8085
						8085
1
1

1971 1972 1973 1974 1975 1976 1977

8-BIT SMALL SYSTEM COMPONENT COUNT 1971 - 1977

1·6

MCS-80/85 specifications

The Intel MCS-80/85 family, introduced in the late 1970s, is a seminal collection of microprocessors that played a pivotal role in the early days of computing. The MCS-80 series, initially targeting embedded systems and control applications, gained remarkable attention due to its innovative architecture and flexible programming capabilities.

The MCS-80 family is anchored by the 8080 microprocessor, which was one of the first fully integrated 8-bit microprocessors. Released in 1974, the 8080 operated at clock speeds ranging from 2 MHz to 3 MHz and featured a 16-bit address bus capable of addressing up to 64KB of memory. The processor’s instruction set included around 78 instructions, providing extensive capabilities for data manipulation, logic operations, and branching.

Complementing the 8080 was a suite of support chips, forming the MCS-80 platform. The most notable among them was the 8155, which integrated a static RAM, I/O ports, and a timer, tailored for ease of designing systems around the 8080. Other support chips included the 8085, which provided improvements with an integrated clock generator, making it compatible with more modern designs and applications.

The MCS-85 series, on the other hand, revolves around the 8085 microprocessor, which provided a more advanced architecture. The 8085 operated at clock speeds of up to 6 MHz and came with a 16-bit address bus, similar to its predecessor. However, it introduced more sophisticated features, including an enhanced instruction set and support for interrupt-driven programming. These enhancements made the 8085 especially appealing to developers working in real-time processing environments.

The MCS-80/85 family utilized NMOS technology, known for its lower power consumption and higher performance compared to previous technologies like TTL. The family’s architecture allowed for easy interfacing with a variety of peripherals, making it a favorite for educational institutions and hobbyists embarking on computer engineering projects.

With its robustness, versatility, and affordability, the Intel MCS-80/85 microprocessors laid the groundwork for many subsequent microcomputer systems and applications. The legacy of this powerful family continues to influence modern microprocessor design, emphasizing the importance of reliable architecture in a rapidly evolving technology landscape.

Intel MCS-80/85 manual MCS·SS Microcomputer System, Evolution

Models: MCS-80/85