MPI 40 Series - Motor on; Drive Select; Side Select; Direction Select

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3.5.1.1 Motor On

In

the

standard

configuration

the

spindle

motor

runs

as

long

as

power

is

applied.

The

motor

may

be

turned

on

and

off

by

the

user

by

controlling

the

optional

MOTOR

ON

signal

line

(refer

to

paragraph

6.7).

When

MOTOR

ON

is

activated

(logical

zero)

the

spindle

motor

is

enabled

in

all

drives

attached

to

the

interface

cable.

The

rotational

speed

of

the

motor

is

controlled

by a

closed

loop

servo

which

requires

some

time

to

achieve

the

desired

speed.

Therefore,

for

proper

functioning

a 500

ms

minimum

delay

after

MOTOR

ON

becomes

active

is

required

prior

to

read/write

oper-

ations.

Refer

to

Figure

3-5.

3.5.1.2 Drive Select 1 - 4

Each

of

the

DRIVE

SELECT

lines,

when

activated

(logical

zero),

selects

the

drive

which

has

the

corresponding

drive

select

jumper

in

place.

In

the

standard

configuration,

the

activation

of

this

line

will

load

the

read/write

heads,

enable

the

stepper

motor,

enable

the

output

lines,

and

light

the

activity

LED.

Only

the

selected

drive

will

respond

to

the

input

lines.

Four

separate

DRIVE

SELECT

lines

are

provided

so

that

up

to

four

drives

may

be

connected

to

a

single

controller.

Jumpers

Bll

-

Cll,

Bl2

-

Cl2,

Bl3

-

Cl3,

and

Bl4 -

Cl4

correspond

to

DRIVE

SELECT

1,

2,

3,

and

4,

respectively.

By

placing

only

one

of

these

jumpers

in

each

drive,

only

one

drive

will

be

selected

when

activating

any

one

of

the

DRIVE

SELECT

lines.

3.5.1.3 Side Select

This

line

is

used

in

the

Model

42

which

utilizes

double

sided

diskettes.

A

logical

one

on

the

SIDE

SELECT

line

selects

the

read/write

head

on

the

lower

side

(side

0)

of

the

diskette

while

logical

zero

selects

the

upper

side

(side

1)

read/write

head.

When

switching

from

one

side

to

the

other,

a 100

us

delay

is

required

prior

to

any

read

or

write

operation.

Refer

to

Figures

3-5

and

3-6.

3.5.1.4 Direction Select

This

input

line

controls

the

direction

the

read/write

heads

will

move when

the

STEP

line

is

pulsed.

A

logical

one

on

this

line

when

the

STEP

line

is

pulsed

moves

the

read/write

heads

away

or

"out"

from

the

center

of

the

diskette.

A

logical

zero

with

pulse(s)

on

the

STEP

line

moves

the

heads

"in"

or

toward

the

center

of

the

diskette.

Refer

to

Figures

3-5

and

3-7.

3-9

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