MCS-85 Applications, Baud Rates | Intel MCS-80/85 specs

MCS-85™ APPLICATIONS

Sample Applications

Calculating Oscilloscope		Intelligent Terminal		Navigation Equipment	Disk Controller
Blood Analyzer		N.C. Machine		Vending Machine	Patient Monitor
Programmable Video Game		Digital Multimeter		Spectrum Analyzer	Network Analyzer
Process Control System		Graphic Terminal		Front End Processor	Frequency Synthesizer
Line Printer		Automotive Control		Credit Verifier

	APPLICATION		PERIPHERAL DEVICES ENCOUNTERED		MCS-85™	COMPONENTS
	Intelligent Terminals		Cathode Ray Tube Display		8275	8085A
			Printing Units		8155	8355
			Synchronous and Asynchronous data lines		8251
			Cassette Tape Unit
			Keyboards		8279
	Gaming Machines		Keyboards, pushbuttons and switches		8279	8085A
			Various display devices			8355
			Coin acceptors		8155
			Coin dispensers
	Cash Registers		Keyboard or Input Switch Array		8279	8085A
			Change Dispenser		8155	8355
			Digital Display
			licket Printer
			Magnetic Card reader
			Communication interface		8273
	Accounting and Billing Machines		Keyboard		8279	8085A
			Printer Unit		8155	8355
			Cassette or other magnetic tape unit		8257
			"Floppy" disks		8271
	Telephone Switching Control		Telephone Line Scanner		8253	8085A
			Analog Switching Network			8355
			Dial Registers		8155
			Class of Service Parcel
	Numerically Controlled Machines		Magnetic or Paper Tape Reader		8155	8085A
			Stepper Motors			8355
			Optical Shaft Encoders
	Process Control		Analog-to-Digital Converters		8155	8085A
			Digital-to-Analog Converters			8355
			Control Switches		8279
			Displays

Baud Rate Generator

Shown in Figure 2 is a minimum system con- figuration with the 8156 timer output connected to an 8085 interrupt input.

This configuration allows convenient use of the timer as a baud rate generator. A 6.144 MHz crystal is used as the frequency control ele- ment of the 8085A, providing integral divisors for the standard baud rates (300, 600, 1200, 2400,4800,9600 baud). The timer is programmed with the appropriate divisor (Figure 1) for the selected baud rate resulting in one pulse on the timer output for each bit cell time. The clock output (elK) of the 8085A is used to clock the timer (TIMERIN). The frequency of this clock is one-half the crystal frequency or in this exam- ple 3.072 MHz. TIMEROUT now provides a crystal controlled pulse train at the baud rate selected.

Serial Communications

By feeding the TIMEROUT signal of the 8156 back to the edge triggered RST 7.5 input of the 8085A, the processor can be interrupt driven at

the required baud rate. As shown in Figure 1, the minimum system supports serial com- munications with only the addition of the send and receive interface circuits.

The SID (SERIAL INPUT DATA) line and the SOD (SERIAL OUTPUT DATA) line are connected directly to a TTY or RS232 interface circuit. Assuming inverted data at the SID input, a direct connection is made to the RST6.5 input for detection of the start bit.

Additional insight into using the 8085'sserial I/O lines in communications application can be found in Section 2 of this Appendix.

	BAUD RATE	COUNT (DECIMAL)

	300	10,240
	600	5,120
	1200	2,560
	2400	1,280
	2400	1,280
	4800	640
	9600	320

FIGURE 1. BAUD RATES

A1-2

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-85 Applications, Baud Rates

Models: MCS-80/85

MCS-85™ APPLICATIONS

Sample Applications

COMPONENTS

FIGURE 1. BAUD RATES

MCS-80/85 specifications