Vliw Architecture

Superscalar architecture was designed to develop the speed of the scalar processor. But it has been realized that it is not easy to execute as we discussed previous. Following are some troubles faced in the superscalar architecture:

• It is required that additional hardware must be provided for hardware parallelism such as decoder, instruction registers, and arithmetic units, etc.
• Scheduling of instructions dynamically to decrease the pipeline delays and to keep all processing units busy is very complex.

Another way to improve the speed of the processor is to develop a sequence of instructions having no dependency and may need different resources, therefore avoiding resource conflicts. The idea is to join these independent instructions in a compact long word incorporating a lot of operations to be implemented simultaneously. That is why; this architecture is known as very long instruction word (VLIW) architecture. In fact, long instruction words take the opcodes of dissimilar instructions, which are dispatched to dissimilar functional units of the processor. In this way, all the operations to be implemented simultaneously by the functional units are synchronized in a VLIW instruction. The size of the VLIW instruction word can be in 100 of bits. VLIW instructions must be formed by compacting small instruction words of conventional program. The job of compaction in VLIW is complete by a compiler. The processor must have the sufficient resources to implement all the operations in VLIW word simultaneously.

For example, one VLIW instruction word is compacted to have store /load operation, floating point multiply, floating point addition, one branch, and one integer arithmetic as shown in Figure.

                            

                                                           VLIW instruction word

 A VLIW processor to support the above instruction word must have the functional components as shown in Figure given below. All the functions units have been incorporated according to the VLIW instruction word. All the elements in the processor share one common large register file.

                      

                                                    VLIW Processor

Parallelism in data movement and instructions should be totally specified at compile time. But scheduling of branch instructions at compile time is very complicated. To handle branch instructions, trace scheduling is adopted. Trace scheduling is based on the prediction of branch decisions with a few reliability at compile time. The prediction is based on some heuristics, hints given by the programmer or using profiles of some earlier program implementations.

Posted Date: 3/4/2013 5:38:36 AM | Location : United States

Ask an Expert

Related Discussions:- Vliw architecture, Assignment Help, Ask Question on Vliw architecture, Get Answer, Expert's Help, Vliw architecture Discussions

Write discussion on Vliw architecture
Your posts are moderated

Write your message here..

Related Questions

Variables and quantifiers - first-order logic, Variables and Quantifiers: ... Variables and Quantifiers: Now we have to diagnose now that if we wanted to say that there is a meal at the Red Lion which costs only 3 pounds, is well sayed. Rather thenif we

Direct mapped cache - computer architecture, Direct Mapping: In this p... Direct Mapping: In this particular technique, block j of the primary memory maps onto block j modulo 128 of the cache. The primary memory blocks 0,128,256,...is loaded

Set up a standard population model structure, Set up a standard population ... Set up a standard population model structure. The population will begin with 24 people. We do not have actual data to support a birth rate, but we could calculate a reasona

Difference between global and local variables, Global and Local Variables ... Global and Local Variables Global variables: The features are as pursue Declared outside of all functions or before main. These can be used in all the functions in the progra

Illustrate the application of e-commerce in home banking, Illustrate the ap... Illustrate the application of E-Commerce in Home Banking. Home Entertainment: E-commerce has show the way to HOME ENTERTAINMENT. The video aspect generally includes a la

Introduction to the sorted arraylist, Consider  a  collection  class  that ... Consider  a  collection  class  that  is  similar  to  the ArrayList  class,  except  that  elements  are sorted in a certain order. We will call this class SortedArrayList. This c

Define the for loop, The for Loop The for loop works well where the num... The for Loop The for loop works well where the number of iterations of the loop is known before the loop is entered. The head of the loop consists of three parts separated by s

What are the advantages of store program control, What are the Advantages o... What are the Advantages of store program control (I) Easy to maintain (II) Easy to control (III) Wide range of services can be provided to customers (IV) Flexible

Explain what is high debugging?, It is helped to recure the bugs. A program... It is helped to recure the bugs. A program has problem that time this debugging is helped to solve the bugs is simply, this is the method of the recure bugs in the programming lang

Communication by message passing, Communication by Message Passing You... Communication by Message Passing You will agree that a single object alone is generally not very helpful. Objects usually emerge as components of a system or a larger program.