PFACC mmreg1, mmreg2/mem64 0Fh 0Fh/AEh Converts packed floating point operand to a packed 32-bit integer. PFADD is a vector instruction that computes addition of the destination operand and source operand (Advanced Micro Devices, Inc., 2000). PFADD mmreg1, mmreg2/mem64 0Fh 0Fh/9Eh Packed, floating-point addition PFCMPEQ is a vector instruction that performs a comparison of the destination and source operands and generates all one bits or all zero bits based on the result (Advanced Micro Devices, Inc., 2000). PFCMPEQ mmreg1, mmreg2/mem64 0Fh 0Fh/B0h Packed, floating-point comparison, equal to PFCMPGE is a vector instruction that compares the destination and source operands and generates all one bits or all zero bits based on …show more content…
This information is used to identify the boundaries between variable length x86 instructions, distinguish DirectPath from VectorPath early-decode instructions, and locate the opcode byte in each instruction (Advanced Micro Devices, Inc., 2000). The predecode logic also detects code branches, such as CALLs, RETURNs and short unconditional JMPs. When a branch is detected, predecoding begins at the target of the branch (Advanced Micro Devices, Inc., 2000). Branch Prediction The fetch logic accesses the branch prediction table at the same time as the instruction cache and uses the branch prediction table information to predict the direction of the branch instructions (Advanced Micro Devices, Inc., 2000). The Athlon uses a combination of a branch target address buffer (BTB), a global history bimodal counter (GHBC) table, and return address stack (RAS) hardware to predict and accelerate branches (Advanced Micro Devices, Inc., 2000). Predicted-taken branches incur only a single-cycle delay to redirect the instruction fetcher to the target instruction. The minimum penalty for a misprediction is ten cycles (Advanced Micro Devices, Inc., 2000). The BTB is a 2048-entry table that caches the predicted target address of a branch in each entry. The Athlon uses a 12-entry return address stack to predict return addresses from a call. As CALLs are fetched, the next extended instruction pointer is pushed onto the return
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The ability of performing logic operation and signal multiplexing in the memory layer will drastically improve the overall system performance, and will also allow better utilization of the underneath CMOS layer (Figure 1 2).
When a conditional branch is fetched from memory, the branch target address is used to index the selector table, this table then determines whether global or local predictor is used. The 2-bit counter in the selector table is updated if the chosen predictor is not taken and other predictor is taken.
1. Consider a processor that supports virtual memory. It has a virtually indexed physically tagged cache, TLB, and page table in memory. Explain what happens in such a processor from the time the CPU generates a virtual address to the point where the referenced memory contents are available to the processor.
Haswell also supports 15 scalar bit manipulation instructions  which consists of bit field manipulations such as insert, extract and shift, bit counting such as zero count , an arbitrary precision integer multiply and rotate .Haswell also has big –endian move instruction (MOVBE)
mm: memory modify (auto-incrementing) This command mm is used to modify the memory contents. It will display the current and address contents which are used as user input. If we enter a legal hexadecimal number, this new value will be written to the address. If we don't enter any value and just press ENTER, then the contents of this address will remain unchanged. The command stops as soon as the data entered is not a hex number as shown in the figure 12.
Memory segmentation is the division of a computer's primary memory information into sections. Segments are applied in object records of compiled programs when linked together into a program image and when the image is loaded into the memory. Segmentation sights a logical address as a collection of segments. Each segment has a name and length. With the addresses specifying both the segment name and the offset within the segment. Therefore the user specifies each address by two quantities: a segment name and an offset. When compared to the paging scheme, the user specifies a single address, which is partitioned by the hardware into a page number and an offset, all invisible to the programmer. Memory segmentation is more visible
Since the invention of the first computer, engineers have been conceptualizing and implementing ways to optimize system performance. The last 25 years have seen a rapid evolution of many of these concepts, particularly cache memory, virtual memory, pipelining, and reduced set instruction computing (RISC). Individual each one of these concepts has helped to increase speed and efficiency thus enhancing overall system performance. Most systems today make use of many, if not all of these concepts. Arguments can be made to support the importance of any one of these concepts over one