MOS KIM-4 User Manual download pdf (Page 9)

CHAPTER

3

THEORY

OF

OPERATION

3.1

Introduction

The

KIM-4

motherboard

is

designed

to

accomplish

three

functions.

The

first

function

is

that

of

distributing

address,

data,

and

control

lines

from

the

KIM-1

to the

expansion

module

connectors

and the bus

expansion

connector.

Those

inter-connections

are

documented

on the

interconnection

list

shown

on

the

schematic

diagram.

The

second

function

is to

buffer,

or

provide

additional

drive,

for the

expansion

modules

from

the

address

and

data

buses.

The

third

function

is to

determine

whether

the

address

present

on the

address

bus is

addressing

a

memory

location

on the

KIM-1

module

or the

KIM-4

motherboard,

and

supply

an

appropriate

signal

to the

decode

line.

The

motherboard

also

contains

regulators

for the +5v and

+12v

supplies

necessary

to

operate

the

KIM-1

and

the

audio

cassette

interface.

3.2

Buffering

Circuitry

U6, U8, and U9

form

a

16-bit

unidirectional

bus

buffer

for the

KIM-1

address

lines.

These

lines

will

normally

be

"on"

at all

times.

The

output

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