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92-525: The XScale architecture is based on the ARMv5TE ISA without the floating-point instructions. XScale uses a seven-stage integer and an eight-stage memory super- pipelined microarchitecture . It is the successor to the Intel StrongARM line of microprocessors and microcontrollers , which Intel acquired from DEC 's Digital Semiconductor division as part of a settlement of a lawsuit between

184-419: A CompactFlash slot or a combination of the two. Although designed for memory, Secure Digital Input/Output (SDIO) and CompactFlash cards were made available that provided peripheral accessories like Wi-Fi or digital cameras to devices with software support. Some PDAs also have a USB port, mainly for USB flash drives . Some PDAs use microSD cards, which are electronically compatible with SD cards, but have

276-535: A calculator , and some sort of memo (or "note") program. PDAs with wireless data connections also typically include an email client and a Web browser, and may or may not include telephony functionality. Many of the original PDAs, such as the Apple Newton and Palm Pilot , featured a touchscreen for user interaction, having only a few buttons—usually reserved for shortcuts to often-used programs. Some touchscreen PDAs, including Windows Mobile devices, had

368-494: A 0.13 μm process, with 4 MB of integrated flash memory and a digital signal processor . A prototype board with the chip was demoed during the Intel Developer Forum. Intel noted it was in talks with leading mobile phone manufacturers, such as Nokia , Motorola , Samsung , Siemens and Sony Ericsson , about incorporating Manitoba into their phones. O2 XM, released in 2005, was the only mobile phone with

460-481: A 2 KB mini data cache (claimed it "avoids 'thrashing' of the D-Cache for frequently changing data streams"). Products based on the third-generation XScale have up to 512 KB unified L2 cache. The XScale core is used in a number of microcontroller families manufactured by Intel and Marvell: There are also standalone processors: the 80200 and 80219 (targeted primarily at PCI applications). PXA System on

552-616: A Chip (SoC) products were designed in Austin, Texas. The code-names for this product line are small towns in Texas, primarily near deer hunting leases frequented by the Intel XScale core and mobile phone SoC marketing team. PXA System on a Chip products were popular on smartphones and PDAs (with Windows Mobile , Symbian OS , Palm OS ) during 2000 to 2006. The PXA210 was Intel's entry-level XScale targeted at mobile phone applications. It

644-508: A PDA with digital cellphone functionality, the 9000 Communicator . Another early entrant in this market was Palm , with a line of PDA products which began in March 1996. Palm would eventually be the dominant vendor of PDAs until the rising popularity of Pocket PC devices in the early 2000s. By the mid-2000s most PDAs had morphed into smartphones as classic PDAs without cellular radios were increasingly becoming uncommon. A typical PDA has

736-517: A PDA, reducing the number of textbooks students were required to carry. Brighton and SUSSEX Medical School in the UK was the first medical school to provide wide scale use of PDAs to its undergraduate students. The learning opportunities provided by having PDAs complete with a suite of key medical texts were studied with results showing that learning occurred in context with timely access to key facts and through consolidation of knowledge via repetition. The PDA

828-505: A basic ALU operation, such as "add", with the access of one or more operands in memory (using addressing modes such as direct, indirect, indexed, etc.). Certain architectures may allow two or three operands (including the result) directly in memory or may be able to perform functions such as automatic pointer increment, etc. Software-implemented instruction sets may have even more complex and powerful instructions. Reduced instruction-set computers , RISC , were first widely implemented during

920-415: A boom in the 1990s and 2000s, PDA's were mostly displaced by the widespread adoption of more highly capable smartphones , in particular those based on iOS and Android in the late 2000's, and thus saw a rapid decline. A PDA has an electronic visual display . Most models also have audio capabilities, allowing usage as a portable media player , and also enabling many of them to be used as telephones. By

1012-401: A cache line or virtual memory page boundary, for instance), and are therefore somewhat easier to optimize for speed. In early 1960s computers, main memory was expensive and very limited, even on mainframes. Minimizing the size of a program to make sure it would fit in the limited memory was often central. Thus the size of the instructions needed to perform a particular task, the code density ,

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1104-509: A central processing unit (CPU), is called an implementation of that ISA. In general, an ISA defines the supported instructions , data types , registers , the hardware support for managing main memory , fundamental features (such as the memory consistency , addressing modes , virtual memory ), and the input/output model of implementations of the ISA. An ISA specifies the behavior of machine code running on implementations of that ISA in

1196-415: A conditional branch instruction will transfer control if the condition is true, so that execution proceeds to a different part of the program, and not transfer control if the condition is false, so that execution continues sequentially. Some instruction sets also have conditional moves, so that the move will be executed, and the data stored in the target location, if the condition is true, and not executed, and

1288-490: A detachable stylus to facilitate making selections. The user interacts with the device by tapping the screen to select buttons or issue commands, or by dragging a finger (or the stylus) on the screen to make selections or scroll. Typical methods of entering text on touchscreen PDAs include: Despite research and development projects, end-users experienced mixed results with handwriting recognition systems. Some found it frustrating and inaccurate, while others were satisfied with

1380-487: A documented use of the Manitoba chip. An Intel executive stated that the chip version used in the phone was reworked to be less expensive than the initial one. The PXA90x, codenamed Hermon , was a successor to Manitoba with 3G support. The PXA90x is built using a 130 nm process. The SoC continued being marketed by Marvell as they acquired Intel's XScale business. PXA16x is a processor designed by Marvell, combining

1472-416: A fashion that does not depend on the characteristics of that implementation, providing binary compatibility between implementations. This enables multiple implementations of an ISA that differ in characteristics such as performance , physical size, and monetary cost (among other things), but that are capable of running the same machine code, so that a lower-performance, lower-cost machine can be replaced with

1564-572: A given instruction may specify: More complex operations are built up by combining these simple instructions, which are executed sequentially, or as otherwise directed by control flow instructions. Examples of operations common to many instruction sets include: Processors may include "complex" instructions in their instruction set. A single "complex" instruction does something that may take many instructions on other computers. Such instructions are typified by instructions that take multiple steps, control multiple functional units, or otherwise appear on

1656-408: A higher-cost, higher-performance machine without having to replace software. It also enables the evolution of the microarchitectures of the implementations of that ISA, so that a newer, higher-performance implementation of an ISA can run software that runs on previous generations of implementations. If an operating system maintains a standard and compatible application binary interface (ABI) for

1748-601: A larger scale than the bulk of simple instructions implemented by the given processor. Some examples of "complex" instructions include: Complex instructions are more common in CISC instruction sets than in RISC instruction sets, but RISC instruction sets may include them as well. RISC instruction sets generally do not include ALU operations with memory operands, or instructions to move large blocks of memory, but most RISC instruction sets include SIMD or vector instructions that perform

1840-474: A much smaller physical size. While early PDAs connected to a user's personal computer via serial ports and other proprietary connections , later models connect via a USB cable. Older PDAs were unable to connect to each other via USB , as their implementations of USB did not support acting as the "host". Some early PDAs were able to connect to the Internet indirectly by means of an external modem connected via

1932-517: A particular ISA, machine code will run on future implementations of that ISA and operating system. However, if an ISA supports running multiple operating systems, it does not guarantee that machine code for one operating system will run on another operating system, unless the first operating system supports running machine code built for the other operating system. An ISA can be extended by adding instructions or other capabilities, or adding support for larger addresses and data values; an implementation of

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2024-419: A period of rapidly growing memory subsystems. They sacrifice code density to simplify implementation circuitry, and try to increase performance via higher clock frequencies and more registers. A single RISC instruction typically performs only a single operation, such as an "add" of registers or a "load" from a memory location into a register. A RISC instruction set normally has a fixed instruction length , whereas

2116-517: A series of five processors spanning a wide range of cost and performance. None of the five engineering design teams could count on being able to bring about adjustments in architectural specifications as a way of easing difficulties in achieving cost and performance objectives. Some virtual machines that support bytecode as their ISA such as Smalltalk , the Java virtual machine , and Microsoft 's Common Language Runtime , implement this by translating

2208-545: A single instruction. Some exotic instruction sets do not have an opcode field, such as transport triggered architectures (TTA), only operand(s). Most stack machines have " 0-operand " instruction sets in which arithmetic and logical operations lack any operand specifier fields; only instructions that push operands onto the evaluation stack or that pop operands from the stack into variables have operand specifiers. The instruction set carries out most ALU actions with postfix ( reverse Polish notation ) operations that work only on

2300-402: A touchscreen for navigation, a memory card slot for data storage, and IrDA , Bluetooth and/or Wi-Fi . However, some PDAs may not have a touchscreen , using soft keys , a directional pad, and a numeric keypad or a thumb keyboard for input. To have the functions expected of a PDA, a device's software typically includes an appointment calendar , a to-do list , an address book for contacts,

2392-473: A touchscreen or small-scale keyboard was slower than a full-size keyboard. Transferring data to a PDA via the computer was, therefore, a lot quicker than having to manually input all data on the handheld device. Most PDAs come with the ability to synchronize to a computer. This is done through synchronization software provided with the handheld, or sometimes with the computer's operating system. Examples of synchronization software include: These programs allow

2484-463: A typical CISC instruction set has instructions of widely varying length. However, as RISC computers normally require more and often longer instructions to implement a given task, they inherently make less optimal use of bus bandwidth and cache memories. Certain embedded RISC ISAs like Thumb and AVR32 typically exhibit very high density owing to a technique called code compression. This technique packs two 16-bit instructions into one 32-bit word, which

2576-540: A writable control store use it to allow the instruction set to be changed (for example, the Rekursiv processor and the Imsys Cjip ). CPUs designed for reconfigurable computing may use field-programmable gate arrays (FPGAs). An ISA can also be emulated in software by an interpreter . Naturally, due to the interpretation overhead, this is slower than directly running programs on the emulated hardware, unless

2668-415: Is 15 bytes (120 bits). Within an instruction set, different instructions may have different lengths. In some architectures, notably most reduced instruction set computers (RISC), instructions are a fixed length , typically corresponding with that architecture's word size . In other architectures, instructions have variable length , typically integral multiples of a byte or a halfword . Some, such as

2760-444: Is a complex issue. There were two stages in history for the microprocessor. The first was the CISC (Complex Instruction Set Computer), which had many different instructions. In the 1970s, however, places like IBM did research and found that many instructions in the set could be eliminated. The result was the RISC (Reduced Instruction Set Computer), an architecture that uses a smaller set of instructions. A simpler instruction set may offer

2852-416: Is a quad core Cortex A7 application processor with Vivante GPU. The IXC1100 processor features clock speeds at 266, 400, and 533 MHz, a 133 MHz bus, 32 KB of instruction cache, 32 KB of data cache, and 2 KB of mini-data cache. It is also designed for low power consumption, using 2.4 W at 533 MHz. The chip comes in the 35 mm PBGA package. The IOP line of processors

XScale - Misplaced Pages Continue

2944-736: Is designed to allow computers and storage devices to transfer data and increase performance by offloading I/O functionality from the main CPU of the device. The IOP3XX processors are based on the XScale architecture and designed to replace the older 80219 sd and i960 family of chips. There are ten different IOP processors currently available: IOP303, IOP310, IOP315, IOP321, IOP331, IOP332, IOP333, IOP341, IOP342 and IOP348. Clock speeds range from 100 MHz to 1.2 GHz. The processors also differ in PCI bus type, PCI bus speed, memory type, maximum memory allowable, and

3036-602: Is due to the many addressing modes and optimizations (such as sub-register addressing, memory operands in ALU instructions, absolute addressing, PC-relative addressing, and register-to-register spills) that CISC ISAs offer. The size or length of an instruction varies widely, from as little as four bits in some microcontrollers to many hundreds of bits in some VLIW systems. Processors used in personal computers , mainframes , and supercomputers have minimum instruction sizes between 8 and 64 bits. The longest possible instruction on x86

3128-505: Is scalable up to 806 MHz. PXA300 and PXA310 deliver performance "scalable to 624 MHz", and are software-compatible with PXA320. Codenamed Manitoba, Intel PXA800F was a SoC introduced by Intel in 2003 for use in GSM - and GPRS -enabled mobile phones. The chip was built around an XScale processor core, the likes of which had been used in PDAs, clocked at 312 MHz and manufactured with

3220-553: Is similar to the code density of RISC; the increased instruction density is offset by requiring more of the primitive instructions to do a task. There has been research into executable compression as a mechanism for improving code density. The mathematics of Kolmogorov complexity describes the challenges and limits of this. In practice, code density is also dependent on the compiler . Most optimizing compilers have options that control whether to optimize code generation for execution speed or for code density. For instance GCC has

3312-538: Is the set of processor design techniques used, in a particular processor, to implement the instruction set. Processors with different microarchitectures can share a common instruction set. For example, the Intel Pentium and the AMD Athlon implement nearly identical versions of the x86 instruction set , but they have radically different internal designs. The concept of an architecture , distinct from

3404-432: Is then unpacked at the decode stage and executed as two instructions. Minimal instruction set computers (MISC) are commonly a form of stack machine , where there are few separate instructions (8–32), so that multiple instructions can be fit into a single machine word. These types of cores often take little silicon to implement, so they can be easily realized in an FPGA or in a multi-core form. The code density of MISC

3496-673: Is used in the BlackBerry Bold 9700 . Little is known about the PXA940, although it is known to be ARM Cortex-A8 compliant. It is utilized in the BlackBerry Torch 9800 and is built using 45 nm technology. After XScale and Sheeva, the PXA98x uses the third CPU core design, this time licensed directly from ARM, in form of dual core Cortex A9 application processors utilized by devices like Samsung Galaxy Tab 3 7.0 . It

3588-504: The ARM with Thumb-extension have mixed variable encoding, that is two fixed, usually 32-bit and 16-bit encodings, where instructions cannot be mixed freely but must be switched between on a branch (or exception boundary in ARMv8). Fixed-length instructions are less complicated to handle than variable-length instructions for several reasons (not having to check whether an instruction straddles

3680-748: The Iyonix PC desktop computer running RISC OS , and the NSLU2 (Slug) running a form of Linux . The XScale is also used in devices such as PVPs (Portable Video Players), PMCs (Portable Media Centres), including the Creative Zen Portable Media Player and Amazon Kindle E-Book reader, and industrial embedded systems. At the other end of the market, the XScale IOP33x Storage I/O processors are used in some Intel Xeon -based server platforms. On June 27, 2006,

3772-574: The StrongARM division from Digital Equipment Corporation in 1998. Intel still holds an ARM license even after the sale of XScale; this license is at the architectural level. Instruction Set In computer science , an instruction set architecture ( ISA ) is an abstract model that generally defines how software controls the CPU in a computer or a family of computers. A device or program that executes instructions described by that ISA, such as

XScale - Misplaced Pages Continue

3864-411: The compiler responsible for instruction issue and scheduling. Architectures with even less complexity have been studied, such as the minimal instruction set computer (MISC) and one-instruction set computer (OISC). These are theoretically important types, but have not been commercialized. Machine language is built up from discrete statements or instructions . On the processing architecture,

3956-417: The instruction pipeline only allow a single memory load or memory store per instruction, leading to a load–store architecture (RISC). For another example, some early ways of implementing the instruction pipeline led to a delay slot . Personal digital assistant A personal digital assistant ( PDA ) is a multi-purpose mobile device which functions as a personal information manager. Following

4048-529: The microarchitecture of a processor, engineers use blocks of "hard-wired" electronic circuitry (often designed separately) such as adders, multiplexers, counters, registers, ALUs, etc. Some kind of register transfer language is then often used to describe the decoding and sequencing of each instruction of an ISA using this physical microarchitecture. There are two basic ways to build a control unit to implement this description (although many designs use middle ways or compromises): Some microcoded CPU designs with

4140-457: The stack or in an implicit register. If some of the operands are given implicitly, fewer operands need be specified in the instruction. When a "destination operand" explicitly specifies the destination, an additional operand must be supplied. Consequently, the number of operands encoded in an instruction may differ from the mathematically necessary number of arguments for a logical or arithmetic operation (the arity ). Operands are either encoded in

4232-431: The "opcode" representation of the instruction, or else are given as values or addresses following the opcode. Register pressure measures the availability of free registers at any point in time during the program execution. Register pressure is high when a large number of the available registers are in use; thus, the higher the register pressure, the more often the register contents must be spilled into memory. Increasing

4324-414: The 1990's to 2006, typically had an IrDA ( infrared ) port allowing short-range, line-of-sight wireless communication. Few later models used this technology, as it had been supplanted by Bluetooth and Wi-Fi. IrDA allows communication between two PDAs, or between a PDA and any device with an IrDA port or adapter. Some contemporary printers have IrDA receivers, allowing IrDA-equipped PDAs to print to them, if

4416-534: The 2700G graphics processor, code named Stanwood, has since been canceled. sd features of Stanwood are integrated into Monahans . For extra graphics capabilities, Intel recommends third-party chips like the Nvidia GoForce chip family. In November 2006, Marvell Semiconductor officially introduced the Monahans family as Marvell PXA320, PXA300, and PXA310. PXA320 is currently shipping in high volume, and

4508-497: The ARM instruction set, not just license a processor core. The acquisition was completed on November 9, 2006. Intel was expected to continue manufacturing XScale processors until Marvell secures other manufacturing facilities, and would continue manufacturing and selling the IXP and IOP processors, as they were not part of the deal. The XScale effort at Intel was initiated by the purchase of

4600-793: The Intel CE 2110 (codenamed Olo River). XScale microprocessors can be found in products such as the popular RIM BlackBerry handheld, the Dell Axim family of Pocket PCs , most of the Zire , Treo and Tungsten Handheld lines by Palm , later versions of the Sharp Zaurus , the Motorola A780 , the Acer n50, the Compaq iPaq 3900 series and many other PDAs . It is used as the main CPU in

4692-740: The PDA and Google's servers. RIM sells BlackBerry Enterprise Server to corporations so that corporate BlackBerry users can wirelessly synchronize their PDAs with the company's Microsoft Exchange Server , IBM Lotus Domino , or Novell GroupWise servers. Email, calendar entries, contacts, tasks, and memos kept on the company's server are automatically synchronized with the BlackBerry. The most common operating systems pre-installed on PDAs are: Other, rarely used operating systems: Some PDAs include Global Positioning System (GPS) receivers. Other PDAs are compatible with external GPS-receiver add-ons that use

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4784-715: The PDA directly, using a cable, or may use wireless technology such as infrared or Bluetooth to connect to the PDA. Newer PDAs, such as the HTC HD2 , Palm Pre , Pre Plus , Pixi , and Pixi Plus , as well as devices running the Android operating system, include more advanced forms of touchscreen that can register multiple touches simultaneously. These " multi-touch " displays allow for more sophisticated interfaces using various gestures entered with one or more fingers. Although many early PDAs did not have memory card slots, later models had either some form of Secure Digital (SD) slot,

4876-458: The PDA manufacturers (for example, GoldMine and IBM Lotus Notes ). Some PDAs can synchronize some or all of their data using their wireless networking capabilities, rather than having to be directly connected to a personal computer via a cable. Devices running Palm's webOS or Google's Android operating system primarily sync with the cloud . For example, if Gmail is used, information in contacts, email, and calendars can be synchronized between

4968-528: The PDA to be synchronized with a personal information manager, which may be part of the computer's operating system, provided with the PDA, or sold separately by a third party. For example, the RIM BlackBerry came with RIM's Desktop Manager program, which can synchronize to both Microsoft Outlook and ACT!. Other PDAs come only with their own proprietary software. For example, some early Palm OS PDAs came only with Palm Desktop, while later Palm PDAs—such as

5060-432: The PDA's operating system supports it. Universal PDA keyboards designed for these older PDAs use infrared technology, due to cost and a lack of wireless interference. Most PDAs can synchronize their data with applications on a user's computer, allowing the user to update contact, schedule, or other information on their computer, using software such as Microsoft Outlook or ACT! , and have that same data transferred to

5152-927: The PDA's processor and screen to display location information. PDAs with GPS functionality can be used for automotive navigation. Integrated PDA's were fitted as standard on new cars throughout the 2000's. PDA-based GPS can also display traffic conditions, perform dynamic routing, and show known locations of roadside mobile radar guns. TomTom , Garmin , and iGO offered GPS navigation software for PDAs. Some businesses and government organizations rely upon rugged PDAs, sometimes known as enterprise digital assistants (EDAs) or mobile computers , for mobile data applications. These PDAs have features that make them more robust and able to handle inclement weather, jolts, and moisture. EDAs often have extra features for data capture, such as barcode readers , radio-frequency identification (RFID) readers, magnetic stripe card readers, or smart card readers. These features are designed to facilitate

5244-615: The PDA's serial port or "sync" connector, or directly by using an expansion card that provided an Ethernet port. Most PDAs use Bluetooth, a popular wireless protocol for mobile devices. Bluetooth can be used to connect keyboards, headsets, GPS receivers , and other nearby accessories. It is also possible to transfer files between PDAs that have Bluetooth. Many PDAs have Wi-Fi wireless network connectivity and can connect to Wi-Fi hotspots. All smartphones, and some other PDAs, can connect to Wireless Wide Area Networks, such as those provided by cellular telecommunications companies. Older PDAs, from

5336-513: The PDA—or transfer updated information from the PDA back to the computer, eliminating the need for the user to update their data in two places. Synchronization also prevents the loss of information stored on the device if it is lost, stolen, or destroyed. When the PDA is repaired or replaced, it can be "re-synced" with the computer, restoring the user's data. Some users found that data input was quicker on their computer than on their PDA since text input via

5428-569: The PXA260 and PXA261-PXA263. The PXA260 is a stand-alone processor clocked at the same frequency as the PXA25x, but features a TPBGA package which is about 53% smaller than the PXA25x's PBGA package. The PXA261-PXA263 are the same as the PXA260 but have Intel StrataFlash memory stacked on top of the processor in the same package; 16 MB of 16-bit memory in the PXA261, 32 MB of 16-bit memory in

5520-745: The PXA262 and 32 MB of 32-bit memory in the PXA263. The PXA26x family was released in March 2003. The PXA27x family (code-named Bulverde ) consists of the PXA270 and PXA271-PXA272 processors. This revision is a huge update to the XScale family of processors. The PXA270 is clocked in four different speeds: 312 MHz, 416 MHz, 520 MHz and 624 MHz and is a stand-alone processor with no packaged memory. The PXA271 can be clocked to 13, 104, 208 MHz or 416 MHz and has 32 MB of 16-bit stacked StrataFlash memory and 32 MB of 16-bit SDRAM in

5612-587: The Sheeva microarchitecture developed by Marvell but upgraded to ARMv7 instruction set compatibility. This core is a so-called Tri-core architecture codenamed Tavor; Tri-core means it supports the ARMv5TE, ARMv6 and ARMv7 instruction sets. This new architecture was a significant leap from the old Xscale architecture. The PXA930 uses 65 nm technology while the PXA935 is built using the 45 nm process. The PXA930

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5704-499: The Treo 650—have the ability to sync to Palm Desktop or Microsoft Outlook. Microsoft's ActiveSync and Windows Mobile Device Center only synchronized with Microsoft Outlook or a Microsoft Exchange server. Third-party synchronization software was also available for some PDAs from companies like CommonTime and CompanionLink . Third-party software can be used to synchronize PDAs to other personal information managers that are not supported by

5796-544: The XScale core is used as both a control and data plane processor, providing both system control and data processing. The task of the XScale in the IXP2XXX devices is typically to provide control plane functionality only, with data processing performed by the microengines , examples of such control plane tasks include routing table updates, microengine control, and memory management. In April 2007, Intel announced an XScale-based processor targeting consumer electronics markets,

5888-595: The bytecode for commonly used code paths into native machine code. In addition, these virtual machines execute less frequently used code paths by interpretation (see: Just-in-time compilation ). Transmeta implemented the x86 instruction set atop VLIW processors in this fashion. An ISA may be classified in a number of different ways. A common classification is by architectural complexity . A complex instruction set computer (CISC) has many specialized instructions, some of which may only be rarely used in practical programs. A reduced instruction set computer (RISC) simplifies

5980-400: The design of a specific machine, was developed by Fred Brooks at IBM during the design phase of System/360 . Prior to NPL [System/360], the company's computer designers had been free to honor cost objectives not only by selecting technologies but also by fashioning functional and architectural refinements. The SPREAD compatibility objective, in contrast, postulated a single architecture for

6072-871: The earlier Intel designed PXA SoC components with a new ARMv5TE CPU core named Mohawk or PJ1 from Marvell's Sheeva family instead of using wdc Xscale or ARM design. The CPU core is derived from the Feroceon core used in Marvell's embedded Kirkwood product line, but extended for instruction level compatibility with the XScale IWMMX. The PXA16x delivers strong performance at a mass market price point for cost sensitive consumer and embedded markets such as digital picture frames, E Readers, multifunction printer user interface (UI) displays, interactive VoIP phones, IP surveillance cameras, and home control gadgets. The PXA930 and PXA935 processor series were again built using

6164-456: The early 2000s, nearly all PDA models had the ability to access the Internet, intranets or extranets via Wi-Fi or Wireless WANs , and since then generally included a web browser . Sometimes, instead of buttons, later PDAs employ touchscreen technology. The first PDA, the Organiser , was released in 1984 by Psion , followed by Psion's Series 3 , in 1991. The latter began to resemble

6256-406: The expression stack , not on data registers or arbitrary main memory cells. This can be very convenient for compiling high-level languages, because most arithmetic expressions can be easily translated into postfix notation. Conditional instructions often have a predicate field—a few bits that encode the specific condition to cause an operation to be performed rather than not performed. For example,

6348-410: The extended ISA will still be able to execute machine code for versions of the ISA without those extensions. Machine code using those extensions will only run on implementations that support those extensions. The binary compatibility that they provide makes ISAs one of the most fundamental abstractions in computing . An instruction set architecture is distinguished from a microarchitecture , which

6440-414: The hardware running the emulator is an order of magnitude faster. Today, it is common practice for vendors of new ISAs or microarchitectures to make software emulators available to software developers before the hardware implementation is ready. Often the details of the implementation have a strong influence on the particular instructions selected for the instruction set. For example, many implementations of

6532-546: The instruction set includes support for something such as " fetch-and-add ", " load-link/store-conditional " (LL/SC), or "atomic compare-and-swap ". A given instruction set can be implemented in a variety of ways. All ways of implementing a particular instruction set provide the same programming model , and all implementations of that instruction set are able to run the same executables. The various ways of implementing an instruction set give different tradeoffs between cost, performance, power consumption, size, etc. When designing

6624-663: The large number of bits needed to encode the three registers of a 3-operand instruction, RISC architectures that have 16-bit instructions are invariably 2-operand designs, such as the Atmel AVR, TI MSP430 , and some versions of ARM Thumb . RISC architectures that have 32-bit instructions are usually 3-operand designs, such as the ARM , AVR32 , MIPS , Power ISA , and SPARC architectures. Each instruction specifies some number of operands (registers, memory locations, or immediate values) explicitly . Some instructions give one or both operands implicitly, such as by being stored on top of

6716-610: The more familiar PDA style, including a full keyboard. The term PDA was first used on 7 January 1992 by Apple Inc. CEO John Sculley at the Consumer Electronics Show in Las Vegas , Nevada , referring to the Apple Newton . In 1994, IBM introduced the first PDA with analog cellular phone functionality, the IBM Simon , which can also be considered the first smartphone. Then in 1996, Nokia introduced

6808-469: The number of processor cores. The XScale core is utilized in the second generation of Intel's IXP network processor line, while the first generation used StrongARM cores. The IXP network processor family ranges from solutions aimed at small/medium office network applications, IXP4XX, to high performance network processors such as the IXP2850, capable of sustaining up to OC-192 line rates. In IXP4XX devices

6900-401: The number of registers in an architecture decreases register pressure but increases the cost. While embedded instruction sets such as Thumb suffer from extremely high register pressure because they have small register sets, general-purpose RISC ISAs like MIPS and Alpha enjoy low register pressure. CISC ISAs like x86-64 offer low register pressure despite having smaller register sets. This

6992-439: The operation to perform, such as add contents of memory to register —and zero or more operand specifiers, which may specify registers , memory locations, or literal data. The operand specifiers may have addressing modes determining their meaning or may be in fixed fields. In very long instruction word (VLIW) architectures, which include many microcode architectures, multiple simultaneous opcodes and operands are specified in

7084-447: The option -Os to optimize for small machine code size, and -O3 to optimize for execution speed at the cost of larger machine code. The instructions constituting a program are rarely specified using their internal, numeric form ( machine code ); they may be specified by programmers using an assembly language or, more commonly, may be generated from high-level programming languages by compilers . The design of instruction sets

7176-476: The potential for higher speeds, reduced processor size, and reduced power consumption. However, a more complex set may optimize common operations, improve memory and cache efficiency, or simplify programming. Some instruction set designers reserve one or more opcodes for some kind of system call or software interrupt . For example, MOS Technology 6502 uses 00 H , Zilog Z80 uses the eight codes C7,CF,D7,DF,E7,EF,F7,FF H while Motorola 68000 use codes in

7268-570: The processor by efficiently implementing only the instructions that are frequently used in programs, while the less common operations are implemented as subroutines, having their resulting additional processor execution time offset by infrequent use. Other types include very long instruction word (VLIW) architectures, and the closely related long instruction word (LIW) and explicitly parallel instruction computing (EPIC) architectures. These architectures seek to exploit instruction-level parallelism with less hardware than RISC and CISC by making

7360-541: The quality of the recognition. Touchscreen PDAs intended for business use, such as the BlackBerry and Palm Treo , usually also offer full keyboards and scroll wheels or thumbwheels to facilitate data entry and navigation. Many touchscreen PDAs support some form of external keyboard as well. Specialized folding keyboards, which offer a full-sized keyboard but collapse into a compact size for transport, were made available for many models. External keyboards may attach to

7452-479: The range A000..AFFF H . Fast virtual machines are much easier to implement if an instruction set meets the Popek and Goldberg virtualization requirements . The NOP slide used in immunity-aware programming is much easier to implement if the "unprogrammed" state of the memory is interpreted as a NOP . On systems with multiple processors, non-blocking synchronization algorithms are much easier to implement if

7544-481: The sale of Intel's XScale PXA mobile processor assets was announced. Intel agreed to sell the XScale PXA business to Marvell Technology Group for an estimated $ 600 million in cash and the assumption of unspecified liabilities. The move was intended to permit Intel to focus its resources on its core x86 and server businesses. Marvell holds a full architecture license for ARM, allowing it to design chips to implement

7636-488: The same arithmetic operation on multiple pieces of data at the same time. SIMD instructions have the ability of manipulating large vectors and matrices in minimal time. SIMD instructions allow easy parallelization of algorithms commonly involved in sound, image, and video processing. Various SIMD implementations have been brought to market under trade names such as MMX , 3DNow! , and AltiVec . On traditional architectures, an instruction includes an opcode that specifies

7728-514: The same package. The PXA272 can be clocked to 312 MHz, 416 MHz or 520 MHz and has 64 MB of 32-bit stacked StrataFlash memory. Intel also added many new technologies to the PXA27x family such as: The PXA27x family was released in April 2004. Along with the PXA27x family Intel released the 2700G embedded graphics co-processor (code-named Marathon). In August 2005 Intel announced

7820-405: The successor to Bulverde , codenamed Monahans . They demonstrated it showing its capability to play back high definition encoded video on a PDA screen. The new processor was shown clocked at 1.25 GHz but Intel said it only offered a 25% increase in performance (800  MIPS for the 624 MHz PXA270 processor vs. 1000 MIPS for 1.25 GHz Monahans ). An announced successor to

7912-524: The target location not modified, if the condition is false. Similarly, IBM z/Architecture has a conditional store instruction. A few instruction sets include a predicate field in every instruction; this is called branch predication . Instruction sets may be categorized by the maximum number of operands explicitly specified in instructions. (In the examples that follow, a , b , and c are (direct or calculated) addresses referring to memory cells, while reg1 and so on refer to machine registers.) Due to

8004-517: The two companies. Intel used the StrongARM to replace its ailing line of outdated RISC processors, the i860 and i960 . All the generations of XScale are 32-bit ARMv5TE processors manufactured with a 0.18 μm or 0.13 μm (as in IXP43x parts) process and have a 32  KB data cache and a 32 KB instruction cache. First- and second-generation XScale multi-core processors also have

8096-432: The use of these devices to scan product or item codes. Typical applications include: PDAs and handheld devices were allowed in many classrooms for digital note-taking. Students could spell-check, modify, and amend their class notes on a PDA. Some educators distributed course material through the Internet or infrared file-sharing functions of the PDA. Textbook publishers released e-books , which can be uploaded directly to

8188-559: Was an important addition to the learning ecology rather than a replacement. Software companies also developed PDA programs to meet the instructional needs of educational institutions, such as dictionaries, thesauri , word processing software, encyclopedias, webinars and digital lesson planners. PDAs were used by music enthusiasts to play a variety of music file formats. Many PDAs include the functionality of an MP3 player. Road rally enthusiasts can use PDAs to calculate distance, speed, and time. This information may be used for navigation, or

8280-753: Was an important characteristic of any instruction set. It remained important on the initially-tiny memories of minicomputers and then microprocessors. Density remains important today, for smartphone applications, applications downloaded into browsers over slow Internet connections, and in ROMs for embedded applications. A more general advantage of increased density is improved effectiveness of caches and instruction prefetch. Computers with high code density often have complex instructions for procedure entry, parameterized returns, loops, etc. (therefore retroactively named Complex Instruction Set Computers , CISC ). However, more typical, or frequent, "CISC" instructions merely combine

8372-512: Was released with the PXA250 in February 2002 and comes clocked at 133 MHz and 200 MHz. The PXA25x family (code-named Cotulla ) consists of the PXA250 and PXA255. The PXA250 was Intel's first generation of XScale processors. There was a choice of three clock speeds : 200  MHz , 300 MHz and 400 MHz. It came out in February 2002. In March 2003, the revision C0 of the PXA250

8464-424: Was renamed to PXA255. The main differences were a doubled internal bus speed (100 MHz to 200 MHz) for faster data transfer, lower core voltage (only 1.3 V at 400 MHz) for lower power consumption and writeback functionality for the data cache, the lack of which had severely impaired performance on the PXA250. Intel XScale Core Features : The PXA26x family (code-named Dalhart ) consists of

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