Introduction

Introduction

For input & output devices only 16 address lines are used.

One device can also need more than one address depending on the size of that device.

Isolated and Memory Mapped I/O

Memory addressing can be either memory mapped or isolated.

In isolated I/O separate 64K space is allocated for the I/O devices.

74LS244 Octal buffer (Input device)

This IC is an octal unidirectional buffer.

This is a 20 pin IC.

Out of 20 pins two are enable pins.

Sending Data To PC

74LS244 IC can be used as an input device for the PC.

For this purpose we can just connect switches at the input of 74LS244 IC and connect the output with PC.

For Figure see lecture.

74LS374 Octal Latch (Output device)

This IC is an octal latch and it can be used as an output device with the PC.

Sending Data From Pc

Connect the input of 74LS374 to the PC.

For Figure see lecture.

Input & Output devices connected to 8088

Interface 74LS374 & 74LS244 at the same time with PC.

For Figure see lecture.