1 / 13

Shift Registers

Shift Registers. pp. 353-356. Shift Registers. Capability to shift bits In one or both directions Why? Part of standard CPU instruction set Cheap multiplication Serial communications Just a chain of flip-flops. Simple 4-Bit Shift Register.

dwilmoth
Download Presentation

Shift Registers

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

  1. Shift Registers pp. 353-356

  2. Shift Registers • Capability to shift bits • In one or both directions • Why? • Part of standard CPU instruction set • Cheap multiplication • Serial communications • Just a chain of flip-flops

  3. Simple 4-Bit Shift Register • In the simplest case, the shift register is simply a set of D flip-flops connected in a row like this: • Shift Registers move data laterally within the register toward its MSB (Most Significant Bit), or LSB (Least Significant Bit) position

  4. Simple 4-Bit Shift Register (continued) • Data input, In, is called a serial input or the shift right input. • Data output, Out, is often called the serial output.

  5. Simple 4-Bit Shift Register (continued) • Clocked in common • The vector (A, B, C, Out) is called the parallel output.

  6. Symbol

  7. Shift Register with Parallel Load • Can provide parallel outputs from flip-flops • And also parallel inputs

  8. Shift Register with Parallel Load (continued) • Shift • Parallel load • “no change” • Schematic next

  9. ------------------------------------ ------------------------------------ Function Table --------------------------------------------- Fig. 7-10 Shift Register with Parallel Load

  10. Why is this useful? • Basis for serial communications • Keyboard • Serial port • Now mainly for modems

  11. Bidirectional Shift Register • Shift either way • Now we have following possible inputs • Parallel load • Shift from left • Shift from right • Also “no change” • Schematic next

  12. Schematic

  13. Shift Registers with Additional Functions • Shift registers can also be designed to shift more than a single bitposition right or left • Shift register can be designed to shift a variable number of bit positions specified by a variable called a shift amount.

More Related