1. FLOPPY DISK INTERFACE

2. Many mass storage devices
like floppy disk drive,hard
disk drive,optical drives
like CD-ROM etc.
Drive unit is responsible for
W/R data to/from storage
medium.
Interface provides these
devices to communicate
with the system.
OVERVIEW
Fig.(a) Floppy disk

3. Interface consists of components like
separate adapter card,separate controller.
The primary interfaces used in PCs today –
Enhanced Integrated Drive Electronics(EIDE) &
Small Computer Systems Interface(SCSI).
Besides EIDE & SCSI, most PCs have separate
controller for floppy disk drives integrated into
the motherboard.

4. When the hard disk drive came over,the floppy
drive remained because it fulfill three
important roles.
 Booting the system
 Distributing software
 Providing removable storage
ROLES OF FLOPPY DRIVES

5. The floppy disk interface consists of three
basic components :
 The floppy drive controller
 The power cable
 The control/data cable
COMPONENTS OF INTERFACE

6.  The FDC was a separate component in the form of an
expansion card that plugged into the system’s
Industry Standard Architecture (ISA) bus.
 When there is a need for other drives such as hard
drives etc requiring controllers then a separate
controller card for each device came to become an
impractical idea.
 Until about 1994, FDC had been integrated into a
multifunction card.
 Today FDC is integrated into motherboard using
super I/O chip
 Function of super I/O chip – it strengthens the
function of standard peripherals into one unit.
FLOPPY DRIVE CONTROLLER (FDC)

7. Fig(b) :The
diagram below
shows a floppy
disc controller
which
communicates
with the CPU
via an
Industry
Standard
Architecture
(ISA) bus.

8.  The speed of the controller had to be increased in order to
send data to the drive at the appropriate rate.
 Higher capacity drivers require a controller with a faster
transmission rate as the disk has higher bit density per track
 The disk is storing more data,so the controller has to feed
more data to the drive in the same amount of time.
FLOPPY CONTROLLER SPEEDS

9. Standard configuration for a FDC is to use IRQ6,Direct
Memory Access,and I/O address 3F0-3F7h.
Should not change the resource allocation of FDC,if a new
device is installing and it conflicts with the FDC change the
configuration of the device and leave the FDC resources
alone.
FLOPPY CONTROLLER RESOURCES

10.  A FDD has two connections to the PC i.e.,a power cable & a
control/data cable.
 The power cable runs from the computer’s power supply to the
drive,carries the power needed to run it.
 Floppy disks requirs two voltages:+5.0V for the logic ckt and
+12.0v for the motors.
 FDD use 4 pin mate-n-lock connector which delivers both of
these voltages plus a ground for each one.
POWER CABLE

11.  The data cable has 34 pins,& different connectors are
designed to support the different drive sizes.
 Function – it carries dta b/w computer and the drive
 New PCs offers a two connector cable.
 A computer uses one cable for all the FDDs,& has two
connectors of each type to support any combination FDD.
 B/w the two pairs of connectors for each drive there is a
cutout that reverses the signals for pins 10 through 16 and
used to differentiate the connectors.
CONTROL/DATA CABLE

12. Fig(c). The
Floppy Drive
control/data
cable

13.  All the odd numbered pins are grounds.
 Functionality of even numbered pins are as follows :-
 pin 2 – indicates whether the disk currently in drive is normal
or high density.
 pin 10 & 16 – signals the motors on each of the two drives to
increase the speed.
 pin 12 & 14 – indicate which drive should be receiving &
processing the incoming signals.
 pin 18 – controls the movement of the drive heads
 pin 20 – instructs the head to move a minute distance.
 pin 22 & 30 – carries the actual data read/write from/to the
disk in the drive
FLOPPY CONTROL/DATA CABLE PINOUTS

14. Fig(d):
Floppy disk
data cable
pin
assignments

15.  pin 24 – indicates whether the drive should be
reading/writing.
 pin 26 – indicates when the drive’s head are positioned over
track 00 on the disk
 pin 28 – specifies whether or not the disk is write protected
 pin 32 – indicates which of the drive’s two heads is activated
 pin 34 – used to signal the system that a new disk has been
inserted into the drive

16.  In data cable no 1 wire different color(red) than other 33
wires so that it can be lined up with the pins on the
motherboard.
 The motherboard have one corner pin numbered as 1 and this
pin goes into the side of cable connector with the coloured
wire.
 To connect cable to the drive attach one of the two connectors
at the end of the cable opposite the motherboard connector.
CONNECTING THE DATA CABLE

17.  There are many problems in interface components
 One of the problem caused by the interface is “phantom drive”
 When there is a new disk in the drive and the OS continues to
display the files on the old disk.
 It is due to the disk change signal not arriving at the
controller over pin 34.
FLOPPY INTERFACE PROBLEMS

18. THANK YOU
Submitted By :
HIMANSHI
&
BHARTI