java barcode reader from image M O D E R N PROCESSOR DESIGN in Software

Painting PDF 417 in Software M O D E R N PROCESSOR DESIGN

M O D E R N PROCESSOR DESIGN
PDF 417 Decoder In None
Using Barcode Control SDK for Software Control to generate, create, read, scan barcode image in Software applications.
PDF 417 Drawer In None
Using Barcode encoder for Software Control to generate, create PDF417 image in Software applications.
M E M O R Y A N D I/O S Y S T E M S
PDF 417 Reader In None
Using Barcode decoder for Software Control to read, scan read, scan image in Software applications.
PDF-417 2d Barcode Creator In C#
Using Barcode generator for .NET framework Control to generate, create PDF417 image in Visual Studio .NET applications.
able 33 ranslating linear physical address to D R A M address* Organization (Figure 39)
PDF 417 Generation In .NET Framework
Using Barcode maker for ASP.NET Control to generate, create PDF417 image in ASP.NET applications.
Painting PDF417 In .NET Framework
Using Barcode creation for VS .NET Control to generate, create PDF 417 image in .NET framework applications.
Serial non-interleaved, 8-bit data b u s Parallel non-interleaved, 32-bit data b u s Serial interleaved, 8-bit data b u s Parallel interleaved 16-bit data b u s
PDF417 Encoder In Visual Basic .NET
Using Barcode maker for VS .NET Control to generate, create PDF 417 image in VS .NET applications.
Code 128A Printer In None
Using Barcode creation for Software Control to generate, create Code 128A image in Software applications.
DRAM Address Breakdown
Draw EAN / UCC - 13 In None
Using Barcode encoder for Software Control to generate, create EAN-13 Supplement 5 image in Software applications.
Encoding Data Matrix ECC200 In None
Using Barcode maker for Software Control to generate, create ECC200 image in Software applications.
16 1211 21 0 RAS | CAS | CS | 16 1211 21 0 RAS 1 CAS | n/a |
USS Code 39 Encoder In None
Using Barcode creation for Software Control to generate, create USS Code 39 image in Software applications.
USS-128 Printer In None
Using Barcode creator for Software Control to generate, create EAN / UCC - 14 image in Software applications.
Example Physical Address
MSI Plessey Generation In None
Using Barcode generator for Software Control to generate, create MSI Plessey image in Software applications.
EAN13 Creation In None
Using Barcode generation for Online Control to generate, create EAN 13 image in Online applications.
0x4321
Code 39 Full ASCII Drawer In Java
Using Barcode generation for BIRT reports Control to generate, create Code-39 image in BIRT reports applications.
Code 3 Of 9 Drawer In Objective-C
Using Barcode generation for iPad Control to generate, create Code 39 Full ASCII image in iPad applications.
Corresponding DRAM Address
Paint UPC - 13 In Visual Basic .NET
Using Barcode encoder for VS .NET Control to generate, create EAN / UCC - 13 image in VS .NET applications.
EAN-13 Scanner In None
Using Barcode recognizer for Software Control to read, scan read, scan image in Software applications.
R A S : 0x4, C A S : 0xC8, CS:0xl
Code 128B Drawer In Java
Using Barcode drawer for Java Control to generate, create Code128 image in Java applications.
Print 1D In .NET
Using Barcode encoder for VS .NET Control to generate, create Linear image in Visual Studio .NET applications.
0x4320
RAS: 0x4, C A S : 0xO3
16 1211 2 1 0 I RAS [ CAS | B a | C S | 16 1211 2 1 0 | RAS | CAS | B a | n / a |
0x8251
RAS: 0x4, C A S : 0x94, Bank: 0x0, CS:0x0
0x8254
R A S : 0x4, C A S : 0x95, Bank: 0x0
Examples assume 4 x 256-kbit DRAM with 8-bit data path and 8-kbit row, for a total of 128 kB of addressable memory
controller is that processor designs must now be synchronized with evolving memory standards As an example, the Opteron processors must be redesigned to take advantage of the new DDR2 DRAM standard, since the onboard controller will only work the older DDR standard In contrast, an off-chip memory controller {North Bridge in the Intel/PC terminology) can be more quickly redesigned and replaced to match new memory standards The ReadQ is used to buffer multiple outstanding reads; this decouples completion of a read from accepting the next one Quite often the processor will issue reads in bursts, as cache misses tend to occur in clusters and accepting multiple reads into the ReadQ prevents the bus from stalling Queueing up multiple requests may also expose more locality that the memory controller can exploit when it schedules DRAM commands Similarly, the WriteQ prevents the bus and processor from stalling by allowing multiple writes to be outstanding at the same time Furthermore, the WriteQ enables a latency-enhancing optimization for reads: since writes are usually not latency-critical, the WriteQ can delay them in favor of outstanding reads, allowing the reads to be satisfied first from the DRAM The delayed writes can be retired whenever there are no pending reads, utilizing idle memory channel cycles M e m o r y Reference Scheduling Of course, reference reordering in the memory controller is subject to the same correctness requirements as a pipelined processor for maintaining read-after-write (RAW), write-after-read (WAR), and write-afterwrite (WAW) dependences In effect, this means that reads cannot be reordered past pending writes to the same address (RAW), writes cannot be reordered past pending reads from the same address (WAR), and writes cannot bypass pending writes to the same address (WAW) If we are only reordering reads with respect to outstanding writes, only the RAW condition needs to be checked If a R A W condition exists between a pending write and a newer read, the read must either stall and wait for the write to be performed against the DRAM, or the read can be satisfied directly from the write queue Either solution will maintain correctness, while the latter should improve performance, since the latency of the read from the on-chip WriteQ will be lower than a read from an external DRAM chip However, in Section 3441 we showed how DRAM chips can exploit spatial locality by fetching multiple words from the same row by issuing different column addresses to the DRAM in back-to-back cycles These references can be satisfied much more quickly than references to different rows, which incur the latency for a row address transfer and row read in the internal DRAM array In current-generation DRAMs, rows can be as large as 8 kilobits; an eight-wide parallel organization (extrapolating from the two-wide parallel scheme shown in Figure 39) would result in an 8-kilobits row in physical memory Accesses to the same row can be satisfied much more quickly than references to other rows Hence, the scheduling logic in advanced memory controllers will attempt to find references to the same row in the ReadQ and WriteQ and attempt to schedule them together to increase the number of row hits This type of scheduling optimization can substantially reduce average DRAM read latency and improve sustained memory bandwidth, but can dramatically complicate the scheduling logic as well as the ReadQ and WriteQ bypass logic
of the n-tuple In general, this selection problem has Q possible solutions, where x is the number of physical address bits and y is the total number of bits needed to specify all the n-tuple elements Table 33 shows only one of these many possible ways of choosing the bits for each element in the DRAM address n-tuple Regardless of which organization is chosen, the RAS bits should be selected to maximize the number of row hits; careful study of the access patterns of important applications can reveal which address bits are the best candidates for RAS Furthermore, in an interleaved design, the bits used for bank selection need to be selected carefully to ensure even distribution of references across the memory banks, since a poor choice of bank bits can direct all references to a single bank, negating any bandwidth benefit expected from the presence of multiple banks Components of a M e m o r y Controller As shown in Figure 37, a memory controller contains more than just an interface to the processor bus and an interface to the DRAM chips It also contains logic for buffering read and write commands from the processor bus (the ReadQ and WriteQ), a response queue (RespQ) for buffering responses heading back to the processor, scheduling logic for issuing DRAM commands to satisfy the processor's read and write requests, and buffer space to assemble wide data responses from multiple narrow DRAM reads This reassembly is needed whenever the processor bus issues read commands that are wider than the DRAM data interface; in such cases multiple DRAM reads have to be performed to assemble a block that matches the width of the processor's read request (which is usually the width of a cache block in the processor's cache) In a similar fashion, wide writes from the processor bus need to be decomposed into multiple narrower writes to the DRAM chips Although Figure 37 shows the memory controller as a physically separate entity, recent designs, exemplified by the AMD Opteron [Keltcher et al 2003], integrate the memory controller directly on chip to minimize memory latency, simplify the chipset design, and reduce overall system cost One of the drawbacks of an on-chip memory
Copyright © OnBarcode.com . All rights reserved.