MPI 40 Series - 3.5.2 Output Signals; Track 00; Index; Index and Sector Timing

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3.5.2 Output Signals

There

are

six

standard

output

lines

and

four

optional

output

lines.

All

output

lines

are

driven

with

open

collector

output

stages

capable

of

sinking

a

maximum

of

48ma

at

a

logical

zero

level

(OV

to

.4V)

at

the

driver.

When

the

driver

is

at

a

logical

one

level

(2.5V

to

5.25V),

the

collector

current

is

a

maximum

of

250

ua.

All

the

output

lines

are

controlled

by

DRIVE

SELECT

and

only

the

selected

drive

sends

its

outputs

to

the

host.

3.5.2.1 Track 00

This

output

line

when

active

(OV

to

.4V)

indicates

the

drive's

read/write

heads

are

positioned

at

the

outermost

track,

and

is

normally

used

to

reset

the

step

counter

in

the

controller

and

initialize

the

step

operation.

Prior

to

any

read/write

oper-

ation,

to

initialize

read/write

position

with

respect

to

data

tracks,

a

"STEP

OUT"

operation

must be performed

until

the

TRACK

00

interface

line

becomes

active.

Refer

to

Figure

3-7.

3.5.2.2 Index

SECTOR

INDEX

This

output

line

sends

a

pulse

to

the

controller

which

indicates

the

beginning

of

a

track

on

each

revolution

of

the

diskette.

Normally,

the

INDEX

pulse

is

a

negative

going

pulse

with

a

period

of

1.7ms +

0.3

ms.

For

a

hard

sectored

diskette,

the

INDEX

signal

is

demultiplexed

from

the

sector

pulses

and

the

pulse

width

is

1.2ms +

0.68ms.

Refer

to

Figure

3-10

for

Index

timing.

31

0 1

31

0

I I I

r-

5.2±.3ms--i

,_-1.7

±

.3ms

i u

I I

--J

r--

2.6 ± .15

ms

/1--l

--u

I I

---i

i--*1.7±.3ms

.,_

_____

166.67 ± 3.33ms

------l

I

I

*FOR

HARD SECTORED DISKETTE INDEX PULSE IS

1.2ms±

.68msWIDE

Figure 3-10: Index and Sector Timing

3-14

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