Intel Pentium 4 Northwood Processor
...sor. Rapid Execution Engine The arithmetic/logic unit (ALU), a component of the CPU, performs arithmetic, comparison and logical operations. Two arithmetic/logic units (ALUs) on the Pentium 4 processor are clocked at twice the core processor frequency. This allows basic integer instructions such as Add, Subtract, Logical AND, Logical OR, etc. to execute in one-half a clock cycle. The Rapid Execution Engine on a 2.53 GHz Pentium 4 processor runs at 5.1 GHz. Level 1 Execution Trace Cache As explained above, there are three levels of cache. Level 1 (L1) cache, also called primary cache, is built directly into the processor chip. The Pentium 4 uses an 8-KB cache. In addition to the 8-KB data cache, the Pentium 4 processor includes an Execution Trace Cache that stores up to 12-K decoded micro-ops in the order of program execution. As the control unit of the processor goes through the four steps of the machine cycle it needs to decode the instructions into commands the computer can execute. The Execution Trace Cache increases performance by removing the decoder from the main execution loop. The result is a means to deliver a high volume of instruction to the processor’s units. Advanced Dynamic Execution The Advanced Dynamic Execution engine is a very deep, out-of-order speculative execution engine that keeps the execution units executing instructions. The Pentium 4 processor can also view 126 instructions in flight and handle up to 48 loads and 24 stores in the pipeline. It also includes an enhanced branch prediction algorithm that has the net effect of reducing the prediction capability. It does this by implementing a 4-KB branch target buffer that stores more detail on the history of past branches, as well as by implementing a more advanced branch prediction algorithm. Advanced Floating-Point and Multimedia Unit The Pentium 4 processor expands the floating-point registers to a full 128-bit and adds an additional register for data movement, which improves performance on both floating-point and multimedia applications. Streaming SIMD Extensions 2 (SSE2) Instructions Today’s processors use MMX™ (multimedia extensions) technology, which is a set of instructions built into the processor that allows it to manipulate and process multimedia data more efficiently. In addition to MMX, Intel’s latest processors include SSE instructions (streaming single-instruction, multiple-data instructions). These technologies further improve the processor’s performance of multimedia, the Web, and 3-D graphics. With the introduction of SSE2, the Intel NetBurst microarchitecture now extends the SIMD capabilities that MMX technology and SSE technology delivered by adding 144 instructions. These instructions include 128-bit SIMD integer arithmetic and 128-bit SIMD double-precision floating-point operations. These instructions reduce the overall number of instructions required to execute a particular program task and as a result can contribute to an overall performance increase. They accelerate a broad range of applications, including video, speech, and image, photo processing, encryption, financial, engineering and scientific applications. How Does It Work? The central processing unit (CPU) or processor is a component of the system unit that interprets and carries out the basic instructions that operate a computer. The CPU contains the control unit and the arithmetic/logic unit (ALU). These two components work together to perform processing operations. The Control Unit The control unit, a component of the CPU, directs and coordinates most of the operations in the computer. The control unit works by first interpreting each instruction issued by a program and then initiating the appropriate action to carry out the instruction. For every instruction, the control unit repeats a set of four basic operations. These operations are: (1) fetching, (2) decoding, (3) executing, and, if necessary, (4) storing. Fetching is the process of obtaining a program instruction or data item from memory. The term decoding refers to the process of translating the instruction into commands the computer can execute. Executing is the process of carrying out the commands. Storing is the process of writing the result to memory. Together, these four operations make up a machine cycle or instruction cycle. The Arithmetic/Logic Unit (ALU) The arithmetic/logic unit (ALU) performs arithmetic, comparison, and logical operations. Arithmetic operations include addition (+), subtraction (-), multiplication (*), and division (/). Comparison operations involve comparing one data item to another to determine if the first item is greater than (>, ), equal to (=), or less than (<, ) the other item. Logical operations use conditions along with logical operators such as AND, OR, and NOT. For example to calculate if an employee qualifies for overtime wages comparison operations are done. If the number of hours worked is greater than say 30, the employee should receive overtime wages for the number of extra hours worked. If this sum is 5 and the overtime wages are at RM5 per hour, arithmetic operations calculate the total wages. However, is only non-salaried employees are entitled to overtime wages, logical operations are used to eliminate workers who are not entitled to overtime wages. Pros and Cons Pros Firstly, the Pentium 4 processor has a very high bus speed of 533-MHz. Bus speed is a very important factor in speeding up the processor. Besides this the small Level 1 Cache also makes for greater speed. Hyper pipelining also is one of the features, which speed up the computer. The excellent branch predictor also makes for fewer mis-predictions. The result is a high-speed computer, which delivers excellent performance in the following areas: Cutting-edge Internet technologies such as streaming video and MP3 audio. Quickly creating, editing and sharing professional-quality photos and video. The ultimate gaming platform for immersing 3D experiences. Internet technologies such as Java, streaming audio and video, 3D, and Web animation. Multi-tasking environments. Background tasks such as real-time virus checking, encryption, compression, and e-mail synchronization. Reduced compiling and rendering times for multimedia applications. Longevity and headroom for future technologies and innovations. Operation of Windows® XP operating system. Cons However, the speed of the processor results in overheating. Also, ...