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76-472: The R5000 is a 64-bit, bi-endian , superscalar , in-order execution 2-issue design microprocessor that implements the MIPS IV instruction set architecture (ISA) developed by Quantum Effect Design (QED) in 1996. The project was funded by MIPS Technologies, Inc (MTI), also the licensor. MTI then licensed the design to Integrated Device Technology (IDT), NEC , NKK , and Toshiba . The R5000 succeeded

152-521: A hex dump ), little-endian representation of integers has the significance increasing from right to left. In other words, it appears backwards when visualized, which can be counter-intuitive. This behavior arises, for example, in FourCC or similar techniques that involve packing characters into an integer, so that it becomes a sequence of specific characters in memory. For example, take the string "JOHN", stored in hexadecimal ASCII . On big-endian machines,

228-481: A 32-bit base address of the segment stored in little-endian order, but in four nonconsecutive bytes, at relative positions 2, 3, 4 and 7 of the descriptor start. Hardware description languages (HDLs) used to express digital logic often support arbitrary endianness, with arbitrary granularity. For example, in SystemVerilog , a word can be defined as little-endian or big-endian. The recognition of endianness

304-455: A 32-byte line size, and are virtually indexed, physically tagged . Instructions were predecoded as they enter the instruction cache by appending four bits to each instruction. These four bits specify whether can be issued together and which execution unit they are executed by. This assisted superscalar instruction issue by moving some of the dependency and conflict checking out of the critical path. The integer unit executes most instructions with

380-467: A 32-cycle latency and throughput for 32-bit integers and a 61-cycle latency and throughput for 64-bit integers. The FPU was not pipelined to save die area and thus cost. This characteristic severely restricted the R4600's floating-point performance, but did not impede its success in low-end computers or embedded applications where integer performance was more important. Single and double precision adds have

456-470: A byte being part of a "field" is its "significance". These attributes of the parts of a field play an important role in the sequence the bytes are accessed by the computer hardware, more precisely: by the low-level algorithms contributing to the results of a computer instruction. Positional number systems (mostly base 2, or less often base 10) are the predominant way of representing and particularly of manipulating integer data by computers. In pure form this

532-413: A four-cycle latency and throughput. Single and double precision multiplies are partially pipelined and have an eight-cycle latency and a six-cycle throughput. Single precision divides have a 32-cycle latency and throughput whereas double precision division have a 61-cycle latency and throughput. Square roots have a latency and throughput is one cycle less than comparative divide instructions. The R4600 uses

608-459: A four-transistor SRAM cell, resulting in a transistor count of 3.6 million and a die that measured 8.7 mm by 9.7 mm (84.39 mm). NEC and NKK fabricated the R5000 in a process with one level of polysilicon and three levels of aluminium interconnect. Without an extra level of polysilicon, both companies had to use a six-transistor SRAM cell, resulting in a transistor count of 5.0 million and

684-440: A larger die with an area of around 87 mm. Die sizes in the range of 80 to 90 mm were claimed by MTI. 0.8 million of the transistors in both versions were for logic, and the remainder contained in the caches. It was packaged in a 272-ball plastic ball grid array (BGA) or 223-pin ceramic pin grid array (PGA). It was not pin-compatible with any previous MIPS microprocessor. In the late 1990s, Quantum Effect Design acquired

760-515: A license to manufacture and sell MIPS microprocessors from MTI and became a microprocessor vendor, changing its name to Quantum Effect Devices to reflect its new business model. The company's first products were members of the RM52xx family, which initially consisted of two models, the RM5230 and RM5260. These were announced on 24 March 1997. The RM5230 was initially available at 100 and 133 MHz, and

836-472: A little-endian should start with FF FE 00 00 . Application binary data formats, such as MATLAB .mat files, or the .bil data format, used in topography, are usually endianness-independent. This is achieved by storing the data always in one fixed endianness or carrying with the data a switch to indicate the endianness. An example of the former is the binary XLS file format that is portable between Windows and Mac systems and always little-endian, requiring

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912-713: A low-end workstation microprocessor, the competition included the IBM and Motorola PowerPC 604 , the HP PA-7300LC and the Intel Pentium Pro . The R5000 is a two-way superscalar design that executes instructions in-order . The R5000 could simultaneously issue an integer and a floating-point instruction. It had one simple pipeline for integer instructions and another for floating-point to save transistors and die area to reduce cost. The R5000 did not perform dynamic branch prediction for cost reasons. Instead it uses

988-399: A new design is often arbitrary, but later technology revisions and updates perpetuate the existing endianness to maintain backward compatibility . A big-endian system stores the most significant byte of a word at the smallest memory address and the least significant byte at the largest. A little-endian system, in contrast, stores the least-significant byte at the smallest address. Of

1064-547: A number of hardware architectures where floating-point numbers are represented in big-endian form while integers are represented in little-endian form. There are ARM processors that have mixed-endian floating-point representation for double-precision numbers: each of the two 32-bit words is stored as little-endian, but the most significant word is stored first. VAX floating point stores little-endian 16-bit words in big-endian order. Because there have been many floating-point formats with no network standard representation for them,

1140-574: A one cycle latency and throughput except for multiply and divide. 32-bit multiplies have a five-cycle latency and a four-cycle throughput. 64-bit multiplies have an extra four cycles of latency and half the throughput. Divides have a 36-cycle latency and throughput for 32-bit integers, and for 64-bit integers, they are increased to 68 cycles. The floating-point unit (FPU) was a fast single-precision (32-bit) design, for reduced cost and to benefit SGI, whose mid-range 3D graphics workstations relied mostly on single-precision math for 3D graphics applications. It

1216-483: A processor treats data accesses. Instruction accesses (fetches of instruction words) on a given processor may still assume a fixed endianness, even if data accesses are fully bi-endian, though this is not always the case, such as on Intel's IA-64 -based Itanium CPU, which allows both. Some nominally bi-endian CPUs require motherboard help to fully switch endianness. For instance, the 32-bit desktop-oriented PowerPC processors in little-endian mode act as little-endian from

1292-436: A setting which allows for switchable endianness in data fetches and stores, instruction fetches, or both; those instruction set architectures are referred to as bi-endian . Architectures that support switchable endianness include PowerPC / Power ISA , SPARC V9, ARM versions 3 and above, DEC Alpha , MIPS , Intel i860 , PA-RISC , SuperH SH-4 , IA-64 , C-Sky , and RISC-V . This feature can improve performance or simplify

1368-406: A single byte, so the complexity of the hardware is not affected by the byte ordering. Addition, subtraction, and multiplication start at the least significant digit position and propagate the carry to the subsequent more significant position. On most systems, the address of a multi-byte value is the address of its first byte (the byte with the lowest address). The implementation of these operations

1444-522: A single positional element (character) also has a positional value. Lexicographical comparison means almost everywhere: first character ranks highest – as in the telephone book. Almost all machines which can do this using a single instruction are big-endian or at least mixed-endian. Integer numbers written as text are always represented most significant digit first in memory, which is similar to big-endian, independently of text direction . When memory bytes are printed sequentially from left to right (e.g. in

1520-525: A static approach, utilizing the hints encoded by the compiler in the branch-likely instructions first introduced in the MIPS II architecture to determine how likely a branch is taken. The R5000 had large L1 caches , a distinct characteristic of QED, whose designers favored simple designs with large caches. The R5000 had two L1 caches, one for instructions and the other for data. Both have a capacity of 32 KB. The caches are two-way set-associative , have

1596-491: A word in a register to the opposite endianness, that is, they swap the order of the bytes in a 16-, 32- or 64-bit word. Recent Intel x86 and x86-64 architecture CPUs have a MOVBE instruction ( Intel Core since generation 4, after Atom ), which fetches a big-endian format word from memory or writes a word into memory in big-endian format. These processors are otherwise thoroughly little-endian. There are also devices which use different formats in different places. For instance,

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1672-520: Is assigned a number, called its address , that the computer uses to access that data. On most modern computers, the smallest data group with an address is eight bits long and is called a byte. Larger groups comprise two or more bytes, for example, a 32-bit word contains four bytes. There are two possible ways a computer could number the individual bytes in a larger group, starting at either end. Both types of endianness are in widespread use in digital electronic engineering. The initial choice of endianness of

1748-406: Is important when reading a file or filesystem created on a computer with different endianness. Fortran sequential unformatted files created with one endianness usually cannot be read on a system using the other endianness because Fortran usually implements a record (defined as the data written by a single Fortran statement) as data preceded and succeeded by count fields, which are integers equal to

1824-481: Is in principle a 16-bit little-endian system. The instructions to convert between floating-point and integer values in the optional floating-point processor of the PDP-11/45, PDP-11/70, and in some later processors, stored 32-bit "double precision integer long" values with the 16-bit halves swapped from the expected little-endian order. The UNIX C compiler used the same format for 32-bit long integers. This ordering

1900-539: Is known as PDP-endian . UNIX was one of the first systems to allow the same code to be compiled for platforms with different internal representations. One of the first programs converted was supposed to print out Unix , but on the Series/1 it printed nUxi instead. A way to interpret this endianness is that it stores a 32-bit integer as two little-endian 16-bit words, with a big-endian word ordering: Segment descriptors of IA-32 and compatible processors keep

1976-434: Is marginally simpler using little-endian machines where this first byte contains the least significant digit. Comparison and division start at the most significant digit and propagate a possible carry to the subsequent less significant digits. For fixed-length numerical values (typically of length 1,2,4,8,16), the implementation of these operations is marginally simpler on big-endian machines. Some big-endian processors (e.g.

2052-406: Is meant as the extremity where the big resp. little significance is written first , namely where the field starts . The integer data that are directly supported by the computer hardware have a fixed width of a low power of 2, e.g. 8 bits ≙ 1 byte, 16 bits ≙ 2 bytes, 32 bits ≙ 4 bytes, 64 bits ≙ 8 bytes, 128 bits ≙ 16 bytes. The low-level access sequence to the bytes of such a field depends on

2128-442: Is redirected to the corresponding address and unaligned access is not allowed. ARMv6 introduces BE-8 or byte-invariant mode, where access to a single byte works as in little-endian mode, but accessing a 16-bit, 32-bit or (starting with ARMv8) 64-bit word results in a byte swap of the data. This simplifies unaligned memory access as well as memory-mapped access to registers other than 32-bit. Many processors have instructions to convert

2204-515: Is used throughout the file. Computer memory consists of a sequence of storage cells (smallest addressable units); in machines that support byte addressing , those units are called bytes . Each byte is identified and accessed in hardware and software by its memory address . If the total number of bytes in memory is n , then addresses are enumerated from 0 to n  − 1. Computer programs often use data structures or fields that may consist of more data than can be stored in one byte. In

2280-413: Is valid for moderate sized non-negative integers, e.g. of C data type unsigned . In such a number system, the value of a digit which it contributes to the whole number is determined not only by its value as a single digit, but also by the position it holds in the complete number, called its significance. These positions can be mapped to memory mainly in two ways: In these expressions, the term "end"

2356-478: The 6809 and the 68000 series of processors use the big-endian format. Solely big-endian architectures include the IBM z/Architecture and OpenRISC . The PDP-11 minicomputer, however, uses little-endian byte order, as does its VAX successor. The Datapoint 2200 used simple bit-serial logic with little-endian to facilitate carry propagation . When Intel developed the 8008 microprocessor for Datapoint, they used little-endian for compatibility. However, as Intel

R5000 - Misplaced Pages Continue

2432-682: The Altera Nios II , the Atmel AVR , the Andes Technology NDS32, the Qualcomm Hexagon , and many other processors and processor families are also little-endian. The Intel 8051 , unlike other Intel processors, expects 16-bit addresses for LJMP and LCALL in big-endian format; however, xCALL instructions store the return address onto the stack in little-endian format. Some instruction set architectures feature

2508-650: The Cray T3E ). IBM AIX and IBM i run in big-endian mode on bi-endian Power ISA; Linux originally ran in big-endian mode, but by 2019, IBM had transitioned to little-endian mode for Linux to ease the porting of Linux software from x86 to Power. SPARC has no relevant little-endian deployment, as both Oracle Solaris and Linux run in big-endian mode on bi-endian SPARC systems, and can be considered big-endian in practice. ARM, C-Sky, and RISC-V have no relevant big-endian deployments, and can be considered little-endian in practice. The term bi-endian refers primarily to how

2584-601: The Emotion Engine with a customized instruction/data cache arrangement and Sony's proprietary 107 vector SIMD Multimedia Extensions(MMI). Its custom FPU is not IEEE 754 compliant unlike FPUs used by R5000. It also has a second MIPS core which acted as a sync controller for specialized vector coprocessors, important for 3D math which at the time was principally computed on the CPU. Bi-endian Computers store information in various-sized groups of binary bits. Each group

2660-463: The Intel Fortran compiler supports the non-standard CONVERT specifier when opening a file, e.g.: OPEN ( unit , CONVERT = 'BIG_ENDIAN' ,...) . Other compilers have options for generating code that globally enables the conversion for all file IO operations. This permits the reuse of code on a system with the opposite endianness without code modification. On most systems,

2736-471: The Internet protocol suite , where it is referred to as network order , transmitting the most significant byte first. Conversely, little-endianness is the dominant ordering for processor architectures ( x86 , most ARM implementations, base RISC-V implementations) and their associated memory. File formats can use either ordering; some formats use a mixture of both or contain an indicator of which ordering

2812-454: The XDR standard uses big-endian IEEE 754 as its representation. It may therefore appear strange that the widespread IEEE 754 floating-point standard does not specify endianness. Theoretically, this means that even standard IEEE floating-point data written by one machine might not be readable by another. However, on modern standard computers (i.e., implementing IEEE 754), one may safely assume that

2888-531: The Add instruction of the IBM 1401 addresses variable-length fields at their low-order (highest-addressed) position with their lengths being defined by a word mark set at their high-order (lowest-addressed) position. When an operation such as addition is performed, the processor begins at the low-order positions at the high addresses of the two fields and works its way down to the high-order. Another important attribute of

2964-675: The BQ27421 Texas Instruments battery gauge uses the little-endian format for its registers and the big-endian format for its random-access memory . SPARC historically used big-endian until version 9, which is bi-endian. Similarly early IBM POWER processors were big-endian, but the PowerPC and Power ISA descendants are now bi-endian. The ARM architecture was little-endian before version 3 when it became bi-endian. Although many processors use little-endian storage for all types of data (integer, floating point), there are

3040-495: The C11 standard and commonly used in code interacting with hardware. Some operations in positional number systems have a natural or preferred order in which the elementary steps are to be executed. This order may affect their performance on small-scale byte-addressable processors and microcontrollers . However, high-performance processors usually fetch multi-byte operands from memory in the same amount of time they would have fetched

3116-720: The IBM System/360 and its successors) contain hardware instructions for lexicographically comparing varying length character strings . The normal data transport by an assignment statement is in principle independent of the endianness of the processor. Many historical and extant processors use a big-endian memory representation, either exclusively or as a design option. The IBM System/360 uses big-endian byte order, as do its successors System/370 , ESA/390 , and z/Architecture . The PDP-10 uses big-endian addressing for byte-oriented instructions. The IBM Series/1 minicomputer uses big-endian byte order. The Motorola 6800 / 6801,

R5000 - Misplaced Pages Continue

3192-615: The Mac application to swap the bytes on load and save when running on a big-endian Motorola 68K or PowerPC processor. R4700 The R4600 , code-named "Orion", is a microprocessor developed by Quantum Effect Design (QED) that implemented the MIPS III instruction set architecture (ISA). As QED was a design firm that did not fabricate or sell their designs, the R4600 was first licensed to Integrated Device Technology (IDT), and later to Toshiba and then NKK . These companies fabricated

3268-626: The QED R4600 and R4700 as their flagship high-end embedded microprocessor. IDT marketed its version of the R5000 as the 79RV5000, NEC as VR5000, NKK as the NR5000, and Toshiba as the TX5000. The R5000 was sold to PMC-Sierra when the company acquired QED. Derivatives of the R5000 are still in production today for embedded systems. Users of the R5000 in workstation and server computers were Silicon Graphics, Inc. (SGI) and Siemens-Nixdorf . SGI used

3344-608: The Qube 2 used the RM5231. The original RaQ systems were equipped with RM5230 or RM5231 CPUs but later models used AMD K6-2 chips and then eventually Intel Pentium III CPUs for the final models. The original roadmap called for 200 MHz operation in early 1996, 250 MHz in late 1996, succeeded in 1997 by R5000A. The R5000 was introduced in January 1996 and failed to achieve 200 MHz, topping out at 180 MHz. When positioned as

3420-468: The R5000 in their O2 and Indy low-end workstations. The R5000 was also used in embedded systems such as network routers and high-end printers. The R5000 found its way into the arcade gaming industry, R5000 powered mainboards were used by Atari and Midway. Initially the Cobalt Qube and Cobalt RaQ used a derivative model, the RM5230 and RM5231. The Qube 2700 used the RM5230 microprocessor, whereas

3496-563: The RM5231A and RM5261A, on 4 April 2001. These microprocessors were fabricated by TSMC in its 0.18 μm process and differ from the previous devices by featuring higher clock rates and lower power consumption. The RM5231A was available at clock rates of 250 to 350 MHz, and the RM5261A from 250 to 400 MHz. R5900 used in Sony's PlayStation 2 is a modified version of R5000 CPU dubbed

3572-481: The RM5260 at 133 and 150 MHz. On 29 September 1997, new 150 and 175 MHz RM5230s were introduced, as were 175 and 200 MHz RM5260s. Both the RM5230 and RM5260 are derivatives of the R5000 and differ in the size of their primary caches (16 KB each instead of 32 KB), the width of their system interfaces (the RM5230 has a 32-bit 67 MHz SysAD bus, and the RM5260 a 64-bit 75 MHz SysAD bus), and

3648-521: The RM5261 and RM5271 were available at 250 and 266 MHz. On 6 July 1999, a 300 MHz RM5271 was introduced, priced at US$ 140 in quantities of 10,000. The RM52x1 improved upon the previous family with larger 32 KB primary caches and a faster SysAD bus that supported clock rates up to 125 MHz. After QED was acquired by PMC-Sierra , the RM52xx and RM52x1 families were continued as PMC-Sierra products. PMC-Sierra introduced two RM52x1 derivatives,

3724-677: The SysAD bus and was shared with the external interface. The SysAD bus is 64 bits wide and can operate at clock rates up to 50 MHz for a peak bandwidth of 400 MB/s. The R4600's external interface did not support multiprocessing . The R4600 needs to be supplied with three clock signals to generate the various clocks. SGI offered a reference design in the form of the UltraP module, aimed at OEMs , permitting R4600 and R4400 processors to work in systems designed for Intel's Pentium processor by employing bus translation logic. As originally announced,

3800-421: The SysAD bus with the external interface. The cache was built with custom synchronous SRAMs (SSRAMs). The microprocessor uses the SysAD bus that is also used by several other MIPS microprocessors. The bus is multiplexed (address and data share the same set of wires) and can operate at clock frequencies up to 100 MHz. The initial R5000 did not support multiprocessing , but the package reserved eight pins for

3876-535: The addition of multiply-add and three-operand multiply instructions for digital signal processing applications. These microprocessors were fabricated by the Taiwan Semiconductor Manufacturing Company (TSMC) in its 0.35 μm process with three levels of interconnect. They were packaged by Amkor Technology in its Power-Quad 4 packages, the RM5230 in a 128-pin version, and the RM5260 in a 208-pin version. The RM52xx family

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3952-421: The address of a multi-byte value is the address of its first byte (the byte with the lowest address); little-endian systems of that type have the property that, for sufficiently low data values, the same value can be read from memory at different lengths without using different addresses (even when alignment restrictions are imposed). For example, a 32-bit memory location with content 4A 00 00 00 can be read at

4028-439: The context of this article where its type cannot be arbitrarily complicated, a "field" consists of a consecutive sequence of bytes and represents a "simple data value" which – at least potentially – can be manipulated by one single hardware instruction . On most systems, the address of a multi-byte simple data value is the address of its first byte (the byte with the lowest address). There are exceptions to this rule – for example,

4104-446: The endianness is the same for floating-point numbers as for integers, making the conversion straightforward regardless of data type. Small embedded systems using special floating-point formats may be another matter, however. Most instructions considered so far contain the size (lengths) of their operands within the operation code . Frequently available operand lengths are 1, 2, 4, 8, or 16 bytes. But there are also architectures where

4180-420: The floating-point unit to perform not only floating-point multiply and divide, but also integer multiply and divide. The R4600 had 16 kB two-way set-associative caches for instructions and data. It supported an L2 cache, but has no on-die hardware to control it, requiring external logic, whether it be a custom application-specific integrated circuit (ASIC) or chipset, to the cache. The cache resided on

4256-481: The future addition of this feature. QED was a fabless company and did not fabricate their own designs. The R5000 was fabricated by IDT, NEC and NKK. All three companies fabricated the R5000 in a 0.35 μm complementary metal–oxide–semiconductor (CMOS) process, but with different process features. IDT fabricated the R5000 in a process with two levels of polysilicon and three levels of aluminium interconnect . The two levels of polysilicon enabled IDT to use

4332-406: The late 1990s (SPARC v9 compliant processors) allow data endianness to be chosen with each individual instruction that loads from or stores to memory. The ARM architecture supports two big-endian modes, called BE-8 and BE-32 . CPUs up to ARMv5 only support BE-32 or word-invariant mode. Here any naturally aligned 32-bit access works like in little-endian mode, but access to a byte or 16-bit word

4408-588: The length of an operand may be held in a separate field of the instruction or with the operand itself, e.g. by means of a word mark . Such an approach allows operand lengths up to 256 bytes or larger. The data types of such operands are character strings or BCD . Machines able to manipulate such data with one instruction (e.g. compare, add) include the IBM 1401 , 1410 , 1620 , System/360 , System/370 , ESA/390 , and z/Architecture , all of them of type big-endian. Numerous other orderings, generically called middle-endian or mixed-endian , are possible. The PDP-11

4484-497: The logic of networking devices and software. The word bi-endian , when said of hardware, denotes the capability of the machine to compute or pass data in either endian format. Many of these architectures can be switched via software to default to a specific endian format (usually done when the computer starts up); however, on some systems, the default endianness is selected by hardware on the motherboard and cannot be changed via software (e.g. Alpha, which runs only in big-endian mode on

4560-555: The microprocessor and marketed it. The R4600 was designed as a low-end workstation or high-end embedded microprocessor. Users included Silicon Graphics, Inc. (SGI) for their Indy workstation and DeskStation Technology for their Windows NT workstations. The R4600 was instrumental in making the Indy successful by providing good integer performance at a competitive price. In embedded systems, prominent users included Cisco Systems in their network routers and Canon in their printers. IDT

4636-456: The module featured both Pentium and R4600 processors, with the Pentium used for initialisation and booting to DOS, and then either the Pentium or R4600 being selected to run an operating system. Subsequent versions were to offer switching between concurrently running operating systems. The R4650 was a derivative of the R4600 announced on 19 October 1994. It had custom instructions for improving

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4712-403: The number of bytes in the data. An attempt to read such a file using Fortran on a system of the other endianness results in a run-time error, because the count fields are incorrect. Unicode text can optionally start with a byte order mark (BOM) to signal the endianness of the file or stream. Its code point is U+FEFF. In UTF-32 for example, a big-endian file should start with 00 00 FE FF ;

4788-416: The operation to be performed. The least-significant byte is accessed first for addition , subtraction and multiplication . The most-significant byte is accessed first for division and comparison . See § Calculation order . When character (text) strings are to be compared with one another, e.g. in order to support some mechanism like sorting , this is very frequently done lexicographically where

4864-604: The performance of fixed-point digital signal processing (DSP) applications. A lower cost version of the R4650, the R4640, was announced on 27 November 1995. It had a 32-bit, instead of a 64-bit, external interface. On 16 September 1997, 150 and 180 MHz versions of both microprocessors were introduced. In quantities of 10,000, the 150 and 180 MHz R4640s were priced at $ 30 and $ 39 each, respectively. The 150 and 180 MHz R4650s were priced at $ 60 and $ 74, respectively. The R4650

4940-560: The point of view of the executing programs, but they require the motherboard to perform a 64-bit swap across all 8 byte lanes to ensure that the little-endian view of things will apply to I/O devices. In the absence of this unusual motherboard hardware, device driver software must write to different addresses to undo the incomplete transformation and also must perform a normal byte swap. Some CPUs, such as many PowerPC processors intended for embedded use and almost all SPARC processors, allow per-page choice of endianness. SPARC processors since

5016-427: The same address as either 8-bit (value = 4A), 16-bit (004A), 24-bit (00004A), or 32-bit (0000004A), all of which retain the same numeric value. Although this little-endian property is rarely used directly by high-level programmers, it is occasionally employed by code optimizers as well as by assembly language programmers. While not allowed by C++, such type punning code is allowed as "implementation-defined" by

5092-507: The two, big-endian is thus closer to the way the digits of numbers are written left-to-right in English, comparing digits to bytes. Bi-endianness is a feature supported by numerous computer architectures that feature switchable endianness in data fetches and stores or for instruction fetches. Other orderings are generically called middle-endian or mixed-endian . Big-endianness is the dominant ordering in networking protocols, such as in

5168-997: The value appears left-to-right, coinciding with the correct string order for reading the result ("J O H N"). But on a little-endian machine, one would see "N H O J". Middle-endian machines complicate this even further; for example, on the PDP-11 , the 32-bit value is stored as two 16-bit words "JO" "HN" in big-endian, with the characters in the 16-bit words being stored in little-endian, resulting in "O J N H". Byte-swapping consists of rearranging bytes to change endianness. Many compilers provide built-ins that are likely to be compiled into native processor instructions ( bswap / movbe ), such as __builtin_bswap32 . Software interfaces for swapping include: Some CPU instruction sets provide native support for endian byte swapping, such as bswap ( x86 — 486 and later, i960 — i960Jx and later ), and rev ( ARMv6 and later). Some compilers have built-in facilities for byte swapping. For example,

5244-457: Was a 100 MHz part fabricated in a 0.5 μm process that used a 3.3 V power supply. The R4600 was a simple design; it was a scalar processor , issuing up to one instruction per cycle to its integer pipeline or floating-point unit (FPU). Most integer instructions have a single cycle latency and throughput, except for multiplies and divides. Multiplies, 32-bit and 64-bit, have an eight-cycle latency and six-cycle throughput. Divides have

5320-471: Was also available in 133 and 167 MHz speeds. These versions of the R4600 processor were used in some arcade games produced by Namco (for example Time Crisis II running on Namco's System 23 hardware). The R4640 was used by WebTV Networks for their WebTV thin clients for the first couple years of its life. R4640 CPUs manufactured by IDT were use in the original WebTV Classic boxes manufactured by Sony and Philips Magnavox in 1996, as well as most of

5396-539: Was fully pipelined, which made it significantly better than that of the R4700 . The R5000 implements the multiply-add instruction of the MIPS IV ISA. Single-precision adds, multiplies and multiply-adds have a four-cycle latency and a one cycle throughput. Single-precision divides have a 21-cycle latency and a 19-cycle throughput, while square roots have a 26-cycle latency and a 38-cycle throughput. Division and square-root

5472-621: Was later joined by the RM5270, which was announced at the Embedded Systems Conference on 29 September 1997. Intended for high-end embedded applications, the RM5270 was available at 150 and 200 MHz. Improvements were the addition of an on-chip secondary cache controller that supported up to 2 MB of cache. The SysAD bus is 64 bits wide and can operate at 100 MHz. It was packaged in a 304-pin Super-BGA (SBGA) that

5548-551: Was not pipelined. Instructions that operate on double precision numbers have a significantly higher latency and lower throughput except for add, which has identical latency and throughput with single-precision add. Multiply and multiply-add have a five-cycle latency and a two-cycle throughput. Divide has a 36-cycle latency and a 34-cycle throughput. Square root has a 68-cycle latency and a 66-cycle throughput. The R5000 had an integrated L2 cache controller that supported capacities of 512 KB, 1 MB and 2 MB. The L2 cache shares

5624-635: Was pin-compatible with the RM7000 and was offered as a migration path to the RM7000. On 20 July 1998, the RM52x1 family was announced. The family consisted of the RM5231, RM5261, and RM5271. These microprocessors were derivatives of the corresponding devices from the RM52x0 family fabricated in a 0.25 μm process with four levels of metal. The RM5231 was initially available at 150, 200, and 250 MHz; whereas

5700-569: Was the first company to fabricate and ship the R4600. IDT produced first silicon in August 1993. The first part was a 100 MHz part announced in October 1993. In March 1994 at CeBIT , IDT announced a 133 MHz part. Both were fabricated in a 0.65 μm CMOS process and required a 5 V power supply. NKK announced their version of the R4600, the NR4600, in the middle of 1994. The first NR4600

5776-513: Was unable to deliver the 8008 in time, Datapoint used a medium-scale integration equivalent, but the little-endianness was retained in most Intel designs, including the MCS-48 and the 8086 and its x86 successors, including IA-32 and x86-64 processors. The MOS Technology 6502 family (including Western Design Center 65802 and 65C816 ), the Zilog Z80 (including Z180 and eZ80 ),

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