Floppy disk interface


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Floppy disk interface

  2. 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. 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. 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. 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. 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. 7. Fig(b) :The diagram below shows a floppy disc controller which communicates with the CPU via an Industry Standard Architecture (ISA) bus.
  8. 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. 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. 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. 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. 12. Fig(c). The Floppy Drive control/data cable
  13. 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. 14. Fig(d): Floppy disk data cable pin assignments
  15. 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. 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. 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. 18. THANK YOU Submitted By : HIMANSHI & BHARTI