INTRODUCTION TO MCS-85™

SYSTEM PERFORMANCE

The true benchmark of any microcomputer- based system is the amount of tasks that can be performed by the system in a given period of time. Increasing speed of CPU instruction ex- ecution has been the common approach to in- creasing system throughput but this puts a greater strain on the memory access require- ment and bus operation than is usually prac- tical for most applications. A much more desirable method would be to distribute the task-load to peripheral devices.

DISTRIBUTED PROCESSING

The concept of distributed task processing is not new to the computer deSigner, but until recently little if any task distribution was available to the microcomputer user. The use of the n~w programmable MCS-80/85 peripherals can rel:leve the central processor of many of the bookk~ping I/O and timing tasks that would otherwise have to be handled by system soft- ware.

INSTRUCTION CYCLE/ACCESS TIME

The basic instruction cycle of the 8085A is 1.3 microseconds, the same speed as the 8080A-1. A close look at the MCS-85 bus operation shows that the access requirement for this speed is only 575 nanoseconds. The MCS-80 access re- quirements for this speed would be under 300 nanoseconds. This illustrates the efficiency and improved timing margins of the MCS-85 bus structure. The new 8085A-2, a high-speed selected version of the 8085A with a .8 micro- second instruction cycle, provides a 60% per- formance improvement over the standard

8085A.

CONCLUSIONS: THROUGHPUT/COST •

When a total system throughput/cost analysis is taken, the MCS-85 system with its advanced processor will yield the most cost-effective, reliable and producible system.

20

1510 ~\~\

rl

\

\

\

 

 

 

 

 

 

 

 

 

 

 

 

---

 

o

 

 

 

 

 

 

 

 

 

 

 

 

 

1

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

1973

1974

1975

1976

1977

1978

 

 

 

 

 

YEAR

 

 

 

 

 

 

 

 

8085A

CPU

 

 

 

 

 

I/O

 

 

MEMORY

 

 

 

 

 

1·13

Page 19 Page 21
Page 20
Image 20
Intel MCS-80/85 System Performance, Distributed Processing, Instruction CYCLE/ACCESS Time, Conclusions THROUGHPUT/COST
Page 19 Page 21

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.
Top Page Image Contents