Schottky Bipolar 8228

SYSTEM CONTROLLER AND BUS DRIVER

FOR 8080A CPU

•Sing.le Chip System Control for MCS:SO Systems

•Built-in Bi-Directional Bus Driver for Data Bus Isolation

•Allows the use of Multiple Byte Instructions (e.g. CAL:L) for Interrupt Acknowledge

•User Selected Single Leve,1 Interrupt Vector (RST 7)

•28 Pin Dual In-Line Package

•Reduces System Package Count

The 8228 is a single chip system controller and bus driver for MCS-80. It generates all signals required to directly interface MCS-80 family RAM, ROM, and I/O components.

Abi-directional bus driver is included to provide high system TTL fan-out. It also provides isolation of the 8080 data bus from memory and I/O. This allows for the optimization of control signals, enabling the sys- tems deisgner to use slower memory and I/O. The isolation of the bus driver also provides for enhanced system noise immunity.

Auser selected single level interrupt vector (RST 7) is provided to simplify real time, interrupt driven, small system requirements. The 8228 also generates the correct control signals to allow the use of multiple byte instructions (e.g., CALL) in response to an INTERRUPT ACKNOWLEDGE by the 8080A. This feature permits large, interrupt driven systems to have an unlimited number of interrupt levels.

The 8228 is designed to support a wide variety of system bus structures and also reduce system package count for cost effective, reliable, design of the MCS-80 systems.

PIN CONFIGURATION

 

8228 BLOCK DIAGRAM

 

STSTB

Vee

 

 

 

 

HLDA

I/OW

CPU

BI·DIRECTIONAL

SYSTEM OATA BUS

 

 

DATA

WR

MEMW

BUS DRIVER

BUS

 

 

 

 

OBIN

IIOR

 

 

 

 

OB4

MEMR

 

 

 

 

04

INTA

 

 

DRIVER CONTROL

OB7

BUSEN

 

 

 

 

07

06

 

 

 

 

OB3

OB6

 

 

 

 

03

05

 

 

 

 

DB2

DBS

 

 

 

 

02

01

STSTB ~----------

 

DBIN - . 0 -------------- 1

 

 

DB~

OB1

WR - . 0 ------------- 011

GND

 

HLDA ~-------------I

0'

 

 

 

 

 

 

PIN NAMES

 

 

 

07·00

DATA BUS (8080 SIDE)

INTA

INTERRUPT ACKNOWLEDGE

 

 

OB7·DBO

DATA BUS (SYSTEM SIDE)

HLOA

HLDA (FROM 8080)

 

 

IIOR

1/0 READ

WR

WR (FROM 8080)

 

 

I!OW

1/0 WRITE

BUSEN

BUS ENABLE INPUT

 

 

MEMR

MEMORY READ

STSTB

STATUS STROBE (FROM 8224)

 

MEMW

MEMORY WR ITE

Vee

+5V

 

 

DBIN

DBIN (FROM 8080)

GND

aVOLTS

 

5-7

Page 68 Page 70
Page 69
Image 69
Intel 8080 manual Dbin, PIN Configuration Block Diagram
Page 68 Page 70

8080 specifications

The Intel 8085 and 8080 microprocessors were groundbreaking innovations in the world of computing, paving the way for future microprocessor development and personal computing.

The Intel 8080, introduced in 1974, was an 8-bit microprocessor that played a fundamental role in the early days of personal computing. With a 16-bit address bus, it had the capability to address 64 KB of memory. Running at clock speeds of 2 MHz, the 8080 was notable for its instruction set, which included 78 instructions and 246 opcodes. It supported a range of addressing modes including direct, indirect, and register addressing. The 8080 was compatible with a variety of peripherals and played a crucial role in the development of many early computers.

The microprocessor's architecture was based on a simple and efficient design, making it accessible for hobbyists and engineers alike. It included an 8-bit accumulator, which allowed for data manipulation and storage during processing. Additionally, the 8080 featured registers like the program counter and stack pointer, which facilitated program flow control and data management. Its ability to handle interrupts also made it suitable for multitasking applications.

The Intel 8085, introduced in 1976, was an enhancement of the 8080 microprocessor. It maintained a similar architecture but included several key improvements. Notably, the 8085 had a built-in clock oscillator, simplifying system design by eliminating the need for external clock circuitry. It also featured a 5-bit control signal for status line management, which allowed for more flexible interfacing with peripheral devices. The 8085 was capable of running at speeds of up to 3 MHz and had an extended instruction set with 74 instructions.

One of the standout features of the 8085 was its support for 5 extra instructions for stack manipulation and I/O operations, which optimized the programming process. Additionally, it supported serial communication, making it suitable for interfacing with external devices. Its 16-bit address bus retained the 64 KB memory addressing capability of its predecessor.

Both the 8080 and 8085 microprocessors laid the groundwork for more advanced microprocessors in the years that followed. They demonstrated the potential of integrated circuits in computing and influenced the design and architecture of subsequent Intel microprocessors. Their legacy endures in the way they revolutionized computing, making technology accessible to a broader audience, and their influence is still felt in the design and architecture of modern microprocessors today.
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