Monday, August 06, 2012

Shift Register

A register is a semiconductor device that is used for storing several bits of digital data. It basically consists of a set of flip-flops, with each flip-flop representing one bit of the register.

Thus, an n-bit register has n flip-flops.

A basic register is also known as a 'latch.'

A special type of register, known as the shift register, is used to pass or transfer bits of data from one flip-flop to another.

This process of transferring data bits from one flip-flop to the next is known as 'shifting'.

Basic Idea of Shift Register


Shift registers are useful for transferring data in a serial manner while allowing parallel access to the data.

A shift register is simply a set of flip-flops interconnected in such a way that the input to a flip-flop is the output of the one before it.

Clocking all the flip-flops at the same time will cause the bits of data to shift or move to the right in one direction (i.e., toward the last flip-flop) .

Figure shows a simple implementation of a 4-bit shift register using D-type flip-flops.



A Simple Shift Register Consisting of D-type Flip-flops
                       
                   
Under its basic operation, the data bit of the last flip-flop is lost once it is clocked out.

In some applications there is a need to bring this back to the first flip-flop, in which case the data will just be circulated within the shift register. A shift register connected this way is known as an end-around-carry shift register, or simply 'ring counter'.






Parallel In Serial Out Shift Register


A more complicated version of a shift register is one that allows shifting in both directions, left or right.

It is aptly and quite descriptively referred to as the Shift-Right Shift-Left Register.

To accomplish this, a 'Mode' control line is added to the circuit. The state of this 'Mode' input determines whether the shift direction would be right or left.

1 comment:

  1. Permit me to introduce you to LE-MERIDIAN FUNDING SERVICES. We are directly into pure loan and project(s) financing in terms of investment. We provide financing solutions to private/companies seeking access to funds in the capital markets i.e. oil and gas, real estate, renewable energy, Pharmaceuticals, Health Care, transportation, construction, hotels and etc. We can finance up to the amount of $900,000,000.000 (Nine Hundred Million Dollars) in any region of the world as long as our 1.9% ROI can be guaranteed on the projects.
    Le-Meridian Funding Service.
    (60 Piccadilly, Mayfair, London W1J 0BH, UK) Email Email Contact....lnfo@lemeridianfds.com

    ReplyDelete

Thank you for your valuable suggestion. If you feel this post useful, please share our Blog with others!!! Comments just for Backlinking your Website or Blog will be Deleted...