Programming for Microprocessors

Introduction

to

the Motorola 6800

FFFF

53

FFEO

8004

8000

03

FF

0000

1

(

Hex

addresses)

ROM

(512 words)

Five peripheral

interfaces

V

Empty

RAM

(1024 words)

Figure

6.2

by

the

combination

(a

15

= 0, a

14

= 1),

regardless

of

the other address

lines.

This could

be

done

by one

Ν AND gate

and one

inverter;

or it

might

be

possible

to use a

chip with independent 'chip select' and

'not

chip select' inputs, and

to

connect

it

directly

to

the system bus without

any explicit address-selection mechanism

at

all.

Of course this method

of

discriminating addresses would place con-

straints

on the

programmer,

who

would

now be

told precisely what

address

to use fo ...