146-409: SPARC ( Scalable Processor ARChitecture ) is a reduced instruction set computer (RISC) instruction set architecture originally developed by Sun Microsystems . Its design was strongly influenced by the experimental Berkeley RISC system developed in the early 1980s. First developed in 1986 and released in 1987, SPARC was one of the most successful early commercial RISC systems, and its success led to
292-554: A 64-bit architecture and was first released in Sun's UltraSPARC processors in 1995. Later, SPARC processors were used in symmetric multiprocessing (SMP) and non-uniform memory access ( CC-NUMA ) servers produced by Sun, Solbourne , and Fujitsu , among others. The design was turned over to the SPARC International trade group in 1989, and since then its architecture has been developed by its members. SPARC International
438-606: A Harvard memory model , where the instruction stream and the data stream are conceptually separated; this means that modifying the memory where code is held might not have any effect on the instructions executed by the processor (because the CPU has a separate instruction and data cache ), at least until a special synchronization instruction is issued; CISC processors that have separate instruction and data caches generally keep them synchronized automatically, for backwards compatibility with older processors. Many early RISC designs also shared
584-446: A linked list , as it is merely a special case of a list. In either case, what identifies the data structure as a stack is not the implementation but the interface: the user is only allowed to pop or push items onto the array or linked list, with few other helper operations. The following will demonstrate both implementations using pseudocode . An array can be used to implement a (bounded) stack, as follows. The first element, usually at
730-470: A register–register architecture ); except for the load/store instructions used to access memory , all instructions operate on the registers, in accordance with the RISC design principles. A SPARC processor includes an integer unit (IU) that performs integer load, store, and arithmetic operations. It may include a floating-point unit (FPU) that performs floating-point operations and, for SPARC V8, may include
876-750: A 24-bit high-speed processor to use as the basis for a digital telephone switch . To reach their goal of switching 1 million calls per hour (300 per second) they calculated that the CPU required performance on the order of 12 million instructions per second (MIPS), compared to their fastest mainframe machine of the time, the 370/168 , which performed at 3.5 MIPS. The design was based on a study of IBM's extensive collection of statistics gathered from their customers. This demonstrated that code in high-performance settings made extensive use of processor registers , and that they often ran out of them. This suggested that additional registers would improve performance. Additionally, they noticed that compilers generally ignored
1022-408: A 5-bit number, for 15 bits. If one of these registers is replaced by an immediate, there is still lots of room to encode the two remaining registers and the opcode. Common instructions found in multi-word systems, like INC and DEC , which reduce the number of words that have to be read before performing the instruction, are unnecessary in RISC as they can be accomplished with a single register and
1168-409: A 64-bit result, SDIVX , which divides a 64-bit signed dividend by a 64-bit signed divisor and produces a 64-bit signed quotient, and UDIVX , which divides a 64-bit unsigned dividend by a 64-bit unsigned divisor and produces a 64-bit signed quotient; none of those instructions use the Y register. Conditional branches test condition codes in a status register , as seen in many instruction sets such
1314-524: A barebones core sufficient for a small embedded processor to supercomputer and cloud computing use with standard and chip designer–defined extensions and coprocessors. It has been tested in silicon design with the ROCKET SoC , which is also available as an open-source processor generator in the CHISEL language. In the early 1980s, significant uncertainties surrounded the RISC concept. One concern involved
1460-400: A better balancing of pipeline stages than before, making RISC pipelines significantly more efficient and allowing higher clock frequencies . Yet another impetus of both RISC and other designs came from practical measurements on real-world programs. Andrew Tanenbaum summed up many of these, demonstrating that processors often had oversized immediates. For instance, he showed that 98% of all
1606-544: A character) as taking their arguments from the stack, and placing any return values back on the stack. For example, PostScript has a return stack and an operand stack, and also has a graphics state stack and a dictionary stack. Many virtual machines are also stack-oriented, including the p-code machine and the Java Virtual Machine . Almost all calling conventions —the ways in which subroutines receive their parameters and return results—use
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#17327807215021752-413: A co-processor (CP) that performs co-processor-specific operations; the architecture does not specify what functions a co-processor would perform, other than load and store operations. The SPARC architecture has an overlapping register window scheme. At any instant, 32 general-purpose registers are visible. A Current Window Pointer ( CWP ) variable in the hardware points to the current set. The total size of
1898-488: A common stack to store both data local to a called procedure and the linking information that allows the procedure to return to its caller. This means that the program moves data into and out of the same stack that contains critical return addresses for the procedure calls. If data is moved to the wrong location on the stack, or an oversized data item is moved to a stack location that is not large enough to contain it, return information for procedure calls may be corrupted, causing
2044-635: A dedicated register for use as the call stack stack pointer with dedicated call, return, push, and pop instructions that implicitly update the dedicated register, thus increasing code density. Some CISC processors, like the PDP-11 and the 68000 , also have special addressing modes for implementation of stacks , typically with a semi-dedicated stack pointer as well (such as A7 in the 68000). In contrast, most RISC CPU designs do not have dedicated stack instructions and therefore most, if not all, registers may be used as stack pointers as needed. Some machines use
2190-426: A destination. If random paths must be chosen, then after following an incorrect path, there must be a method by which to return to the beginning of that path. This can be achieved through the use of stacks, as a last correct point can be pushed onto the stack, and popped from the stack in case of an incorrect path. The prototypical example of a backtracking algorithm is depth-first search , which finds all vertices of
2336-452: A different opcode. In contrast, a 32-bit machine has ample room to encode an immediate value, and doing so avoids the need to do a second memory read to pick up the value. This is why many RISC processors allow a 12- or 13-bit constant to be encoded directly into the instruction word. Assuming a 13-bit constant area, as is the case in the MIPS and RISC designs, another 19 bits are available for
2482-404: A fixed location in memory at which it begins. As data items are added to the stack, the stack pointer is displaced to indicate the current extent of the stack, which expands away from the origin. Stack pointers may point to the origin of a stack or to a limited range of addresses above or below the origin (depending on the direction in which the stack grows); however, the stack pointer cannot cross
2628-479: A graph that can be reached from a specified starting vertex. Other applications of backtracking involve searching through spaces that represent potential solutions to an optimization problem. Branch and bound is a technique for performing such backtracking searches without exhaustively searching all of the potential solutions in such a space. A number of programming languages are stack-oriented , meaning they define most basic operations (adding two numbers, printing
2774-425: A new item is pushed onto the stack; if it points to the next available location in the stack, it will be updated after the new item is pushed onto the stack. Popping the stack is simply the inverse of pushing. The topmost item in the stack is removed and the stack pointer is updated, in the opposite order of that used in the push operation. Many CISC -type CPU designs, including the x86 , Z80 and 6502 , have
2920-587: A new specification, Oracle SPARC Architecture 2011 , which besides the overall update of the reference, adds the VIS 3 instruction set extensions and hyperprivileged mode to the 2007 specification. In October 2015, Oracle released SPARC M7, the first processor based on the new Oracle SPARC Architecture 2015 specification. This revision includes VIS 4 instruction set extensions and hardware-assisted encryption and silicon secured memory (SSM). SPARC architecture has provided continuous application binary compatibility from
3066-493: A number of additional points. Among these was the fact that programs spent a significant amount of time performing subroutine calls and returns, and it seemed there was the potential to improve overall performance by speeding these calls. This led the Berkeley design to select a method known as register windows which can significantly improve subroutine performance although at the cost of some complexity. They also noticed that
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#17327807215023212-598: A paper on ways to improve microcoding, but later changed his mind and decided microcode itself was the problem. With funding from the DARPA VLSI Program , Patterson started the Berkeley RISC effort. The Program, practically unknown today, led to a huge number of advances in chip design, fabrication, and even computer graphics. Considering a variety of programs from their BSD Unix variant, the Berkeley team found, as had IBM, that most programs made no use of
3358-484: A particular strategy for implementing some RISC designs, and modern RISC designs generally do away with it (such as PowerPC and more recent versions of SPARC and MIPS). Some aspects attributed to the first RISC- labeled designs around 1975 include the observations that the memory-restricted compilers of the time were often unable to take advantage of features intended to facilitate manual assembly coding, and that complex addressing modes take many cycles to perform due to
3504-413: A pipelined processor and for code generation by an optimizing compiler. A common misunderstanding of the phrase "reduced instruction set computer" is that instructions are simply eliminated, resulting in a smaller set of instructions. In fact, over the years, RISC instruction sets have grown in size, and today many of them have a larger set of instructions than many CISC CPUs. Some RISC processors such as
3650-400: A plus sign separating the operands, instead of using a comma-separated list. Examples: Due to the widespread use of non-32-bit data, such as 16-bit or 8-bit integral data or 8-bit bytes in strings, there are instructions that load and store 16-bit half-words and 8-bit bytes, as well as instructions that load 32-bit words. During a load, those instructions will read only the byte or half-word at
3796-447: A quad-aligned group of four floating-point registers can hold one quad-precision IEEE 754 floating-point number. A SPARC V9 processor with an FPU includes: The registers are organized as a set of 64 32-bit registers, with the first 32 being used as the 32-bit floating-point registers, even–odd pairs of all 64 registers being used as the 64-bit floating-point registers, and quad-aligned groups of four floating-point registers being used as
3942-627: A rate of almost one instruction per clock cycle . This made them similar to the MIPS architecture in many ways, including the lack of instructions such as multiply or divide. Another feature of SPARC influenced by this early RISC movement is the branch delay slot . The SPARC processor usually contains as many as 160 general-purpose registers . According to the "Oracle SPARC Architecture 2015" specification an "implementation may contain from 72 to 640 general-purpose 64-bit" registers. At any point, only 32 of them are immediately visible to software — 8 are
4088-469: A reasonably sized constant in a 32-bit instruction word. Since many real-world programs spend most of their time executing simple operations, some researchers decided to focus on making those operations as fast as possible. The clock rate of a CPU is limited by the time it takes to execute the slowest sub-operation of any instruction; decreasing that cycle-time often accelerates the execution of other instructions. The focus on "reduced instructions" led to
4234-423: A register holds the value 10 and then branch to code that handles it, one would: In a conditional branch instruction, the icc or fcc field specifies the condition being tested. The 22-bit displacement field is the address, relative to the current PC, of the target, in words, so that conditional branches can go forward or backward up to 8 megabytes. The ANNUL (A) bit is used to get rid of some delay slots. If it
4380-522: A register or a 13-bit signed integer constant; the other operands are registers. Any of the register operands may point to G0; pointing the result to G0 discards the results, which can be used for tests. Examples include: The list of mathematical instructions is ADD , SUB , AND , OR , XOR , and negated versions ANDN , ORN , and XNOR . One quirk of the SPARC design is that most arithmetic instructions come in pairs, with one version setting
4526-459: A restricted API with only push/pop operations. PHP has an SplStack class. Java's library contains a Stack class that is a specialization of Vector . Following is an example program in Java language, using that class. A common use of stacks at the architecture level is as a means of allocating and accessing memory. A typical stack is an area of computer memory with a fixed origin and
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4672-506: A sequence of simpler internal instructions. In the 68k, a full 1 ⁄ 3 of the transistors were used for this microcoding. In 1979, David Patterson was sent on a sabbatical from the University of California, Berkeley to help DEC's west-coast team improve the VAX microcode. Patterson was struck by the complexity of the coding process and concluded it was untenable. He first wrote
4818-503: A sequence of simpler operations doing the same thing. This was in part an effect of the fact that many designs were rushed, with little time to optimize or tune every instruction; only those used most often were optimized, and a sequence of those instructions could be faster than a less-tuned instruction performing an equivalent operation as that sequence. One infamous example was the VAX 's INDEX instruction. The Berkeley work also turned up
4964-498: A set of global registers (one of which, g0 , is hard-wired to zero, so only seven of them are usable as registers) and the other 24 are from the stack of registers. These 24 registers form what is called a register window , and at function call/return, this window is moved up and down the register stack. Each window has eight local registers and shares eight registers with each of the adjacent windows. The shared registers are used for passing function parameters and returning values, and
5110-457: A single complex instruction such as STRING MOVE , but hide those details from the compiler. The internal operations of a RISC processor are "exposed to the compiler", leading to the backronym 'Relegate Interesting Stuff to the Compiler'. Most RISC architectures have fixed-length instructions and a simple encoding, which simplifies fetch, decode, and issue logic considerably. This is among
5256-482: A single data memory cycle—compared to the "complex instructions" of CISC CPUs that may require dozens of data memory cycles in order to execute a single instruction. The term load–store architecture is sometimes preferred. Another way of looking at the RISC/CISC debate is to consider what is exposed to the compiler. In a CISC processor, the hardware may internally use registers and flag bit in order to implement
5402-434: A special stack (the " call stack ") to hold information about procedure/function calling and nesting in order to switch to the context of the called function and restore to the caller function when the calling finishes. The functions follow a runtime protocol between caller and callee to save arguments and return value on the stack. Stacks are an important way of supporting nested or recursive function calls. This type of stack
5548-455: A specific type of data that can be provided to such a program such that the return address of the current procedure is reset to point to an area within the stack itself (and within the data provided by the attacker), which in turn contains instructions that carry out unauthorized operations. This type of attack is a variation on the buffer overflow attack and is an extremely frequent source of security breaches in software, mainly because some of
5694-503: A stack for arithmetic and logical operations; operands are pushed onto the stack, and arithmetic and logical operations act on the top one or more items on the stack, popping them off the stack and pushing the result onto the stack. Machines that function in this fashion are called stack machines . A number of mainframes and minicomputers were stack machines, the most famous being the Burroughs large systems . Other examples include
5840-424: A stack of plates. The order in which an element added to or removed from a stack is described as last in, first out , referred to by the acronym LIFO . As with a stack of physical objects, this structure makes it easy to take an item off the top of the stack, but accessing a datum deeper in the stack may require removing multiple other items first. Considered a sequential collection, a stack has one end which
5986-417: A stack. Many compilers use a stack to parse syntax before translation into low-level code. Most programming languages are context-free languages , allowing them to be parsed with stack-based machines. Another important application of stacks is backtracking . An illustration of this is the simple example of finding the correct path in a maze that contains a series of points, a starting point, several paths and
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6132-412: A variable size. Initially the size of the stack is zero. A stack pointer (usually in the form of a processor register ) points to the most recently referenced location on the stack; when the stack has a size of zero, the stack pointer points to the origin of the stack. The two operations applicable to all stacks are: There are many variations on the basic principle of stack operations. Every stack has
6278-613: A very small set of instructions—but these designs are very different from classic RISC designs, so they have been given other names such as minimal instruction set computer (MISC) or transport triggered architecture (TTA). RISC architectures have traditionally had few successes in the desktop PC and commodity server markets, where the x86 -based platforms remain the dominant processor architecture. However, this may change, as ARM-based processors are being developed for higher performance systems. Manufacturers including Cavium , AMD, and Qualcomm have released server processors based on
6424-501: A year later for their mainframe and end-of-support in 2034 "to promote customer modernization". The SPARC architecture was heavily influenced by the earlier RISC designs, including the RISC I and II from the University of California, Berkeley and the IBM 801 . These original RISC designs were minimalist, including as few features or op-codes as possible and aiming to execute instructions at
6570-723: Is 0 in a conditional branch, the delay slot is executed as usual. If it is 1, the delay slot is only executed if the branch is taken. If it is not taken, the instruction following the conditional branch is skipped. There are a wide variety of conditional branches: BA (branch always, essentially a jmp), BN (branch never), BE (equals), BNE (not equals), BL (less than), BLE (less or equal), BLEU (less or equal, unsigned), BG (greater), BGE (greater or equal), BGU (greater unsigned), BPOS (positive), BNEG (negative), BCC (carry clear), BCS (carry set), BVC (overflow clear), BVS (overflow set). The FPU and CP have sets of condition codes separate from
6716-472: Is also responsible for licensing and promoting the SPARC architecture, managing SPARC trademarks (including SPARC, which it owns), and providing conformance testing . SPARC International was intended to grow the SPARC architecture to create a larger ecosystem; SPARC has been licensed to several manufacturers, including Atmel , Bipolar Integrated Technology , Cypress Semiconductor , Fujitsu , Matsushita and Texas Instruments . Due to SPARC International, SPARC
6862-437: Is created by adding the two address operands to produce an address. The second address operand may be a constant or a register. Loads take the value at the address and place it in the register specified by the third operand, whereas stores take the value in the register specified by the first operand and place it at the address. To make this more obvious, the assembler language indicates address operands using square brackets with
7008-429: Is deposited. The majority of SPARC instructions have at least this register, so it is placed near the "front" of the instruction format. RS1 and RS2 are the "source registers", which may or may not be present, or replaced by a constant. Load and store instructions have a three-operand format, in that they have two operands representing values for the address and one operand for the register to read or write to. The address
7154-593: Is fully open, non-proprietary and royalty-free. As of 2024, the latest commercial high-end SPARC processors are Fujitsu 's SPARC64 XII (introduced in September 2017 for its SPARC M12 server) and Oracle 's SPARC M8 introduced in September 2017 for its high-end servers. On September 1, 2017, after a round of layoffs that started in Oracle Labs in November 2016, Oracle terminated SPARC design after completing
7300-460: Is needed to implement depth-first search . Stacks entered the computer science literature in 1946, when Alan Turing used the terms "bury" and "unbury" as a means of calling and returning from subroutines. Subroutines and a two-level stack had already been implemented in Konrad Zuse 's Z4 in 1945. Klaus Samelson and Friedrich L. Bauer of Technical University Munich proposed
7446-433: Is the only position at which the push and pop operations may occur, the top of the stack, and is fixed at the other end, the bottom . A stack may be implemented as, for example, a singly linked list with a pointer to the top element. A stack may be implemented to have a bounded capacity. If the stack is full and does not contain enough space to accept another element, the stack is in a state of stack overflow . A stack
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#17327807215027592-437: Is used implicitly by the compiler to support CALL and RETURN statements (or their equivalents) and is not manipulated directly by the programmer. Some programming languages use the stack to store data that is local to a procedure. Space for local data items is allocated from the stack when the procedure is entered, and is deallocated when the procedure exits. The C programming language is typically implemented in this way. Using
7738-446: Is usually represented in computers by a block of memory cells, with the "bottom" at a fixed location, and the stack pointer holding the address of the current "top" cell in the stack. The "top" and "bottom" nomenclature is used irrespective of whether the stack actually grows towards higher memory addresses. Pushing an item on to the stack adjusts the stack pointer by the size of the item (either decrementing or incrementing, depending on
7884-490: The LD instruction, renamed LDUW , clears the upper 32 bits in the register and loads the 32-bit value into the lower 32 bits, and the ST instruction, renamed STW , discards the upper 32 bits of the register and stores only the lower 32 bits. The new LDSW instruction sets the upper bits in the register to the value of the uppermost bit of the word and loads the 32-bit value into
8030-550: The Adapteva Epiphany , have an optional short, feature-reduced compressed instruction set . Generally, these instructions expose a smaller number of registers and fewer bits for immediate values, and often use a two-operand format to eliminate one register number from instructions. A two-operand format in a system with 16 registers requires 8 bits for register numbers, leaving another 8 for an opcode or other uses. The SH5 also follows this pattern, albeit having evolved in
8176-557: The COP400 , implements a stack either directly in hardware or in RAM via a stack pointer, depending on the device. Many stack-based microprocessors were used to implement the programming language Forth at the microcode level. Calculators that employ reverse Polish notation use a stack structure to hold values. Expressions can be represented in prefix, postfix or infix notations and conversion from one form to another may be accomplished using
8322-623: The DEC Alpha , AMD Am29000 , Intel i860 and i960 , Motorola 88000 , IBM POWER , and, slightly later, the IBM/Apple/Motorola PowerPC . Many of these have since disappeared due to them often offering no competitive advantage over others of the same era. Those that remain are often used only in niche markets or as parts of other systems; of the designs from these traditional vendors, only SPARC and POWER have any significant remaining market. The ARM architecture has been
8468-511: The IBM System/360 architecture and successors and the x86 architecture. This means that a test and branch is normally performed with two instructions; the first is an ALU instruction that sets the condition codes, followed by a branch instruction that examines one of those flags. The SPARC does not have specialized test instructions; tests are performed using normal ALU instructions with the destination set to %G0. For instance, to test if
8614-529: The RT PC —was less competitive than others, but the success of SPARC renewed interest within IBM, which released new RISC systems by 1990 and by 1995 RISC processors were the foundation of a $ 15 billion server industry. By the later 1980s, the new RISC designs were easily outperforming all traditional designs by a wide margin. At that point, all of the other vendors began RISC efforts of their own. Among these were
8760-689: The UltraSPARC T1 implementation: In 2007, Sun released an updated specification, UltraSPARC Architecture 2007 , to which the UltraSPARC T2 implementation complied. In December 2007, Sun also made the UltraSPARC T2 processor's RTL available via the OpenSPARC project. It was also released under the GNU General public license v2. OpenSPARC T2 is 8 cores, 16 pipelines with 64 threads. In August 2012, Oracle Corporation made available
8906-455: The laser printer , the router , and similar products. In the minicomputer market, companies that included Celerity Computing , Pyramid Technology , and Ridge Computers began offering systems designed according to RISC or RISC-like principles in the early 1980s. Few of these designs began by using RISC microprocessors . The varieties of RISC processor design include the ARC processor,
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#17327807215029052-409: The load–store approach. The term RISC was coined by David Patterson of the Berkeley RISC project, although somewhat similar concepts had appeared before. The CDC 6600 designed by Seymour Cray in 1964 used a load–store architecture with only two addressing modes (register+register, and register+immediate constant) and 74 operation codes, with the basic clock cycle being 10 times faster than
9198-443: The register file for all (two or three) operands. A stack structure also makes superscalar implementations with register renaming (for speculative execution ) somewhat more complex to implement, although it is still feasible, as exemplified by modern x87 implementations. Sun SPARC , AMD Am29000 , and Intel i960 are all examples of architectures that use register windows within a register-stack as another strategy to avoid
9344-406: The zero offset , is the bottom, resulting in array[0] being the first element pushed onto the stack and the last element popped off. The program must keep track of the size (length) of the stack, using a variable top that records the number of items pushed so far, therefore pointing to the place in the array where the next element is to be inserted (assuming a zero-based index convention). Thus,
9490-412: The 128-bit floating-point registers. Floating-point registers are not windowed; they are all global registers. All SPARC instructions occupy a full 32-bit word and start on a word boundary. Four formats are used, distinguished by the first two bits. All arithmetic and logical instructions have 2 source operands and 1 destination operand. RD is the "destination register", where the output of the operation
9636-557: The 1980s as the MIPS and SPARC systems. IBM eventually produced RISC designs based on further work on the 801 concept, the IBM POWER architecture , PowerPC , and Power ISA . As the projects matured, many similar designs, produced in the mid-to-late 1980s and early 1990s, such as ARM , PA-RISC , and Alpha , created central processing units that increased the commercial utility of the Unix workstation and of embedded processors in
9782-707: The ARM architecture. ARM further partnered with Cray in 2017 to produce an ARM-based supercomputer. On the desktop, Microsoft announced that it planned to support the PC version of Windows 10 on Qualcomm Snapdragon -based devices in 2017 as part of its partnership with Qualcomm. These devices will support Windows applications compiled for 32-bit x86 via an x86 processor emulator that translates 32-bit x86 code to ARM64 code . Apple announced they will transition their Mac desktop and laptop computers from Intel processors to internally developed ARM64-based SoCs called Apple silicon ;
9928-545: The Berkeley RISC-II system. The US government Committee on Innovations in Computing and Communications credits the acceptance of the viability of the RISC concept to the success of the SPARC system. By 1989 many RISC CPUs were available; competition lowered their price to $ 10 per MIPS in large quantities, much less expensive than the sole sourced Intel 80386 . The performance of IBM's RISC CPU—only available in
10074-626: The CISC HP 3000 machines and the CISC machines from Tandem Computers . The x87 floating point architecture is an example of a set of registers organised as a stack where direct access to individual registers (relative to the current top) is also possible. Having the top-of-stack as an implicit argument allows for a small machine code footprint with a good usage of bus bandwidth and code caches , but it also prevents some types of optimizations possible on processors permitting random access to
10220-503: The CPU allows RISC computers few simple addressing modes and predictable instruction times that simplify design of the system as a whole. The conceptual developments of the RISC computer architecture began with the IBM 801 project in the late 1970s, but these were not immediately put into use. Designers in California picked up the 801 concepts in two seminal projects, Stanford MIPS and Berkeley RISC . These were commercialized in
10366-638: The DEC Alpha, the AMD Am29000 , the ARM architecture, the Atmel AVR , Blackfin , Intel i860 , Intel i960 , LoongArch , Motorola 88000 , the MIPS architecture, PA-RISC, Power ISA, RISC-V , SuperH , and SPARC. RISC processors are used in supercomputers , such as the Fugaku . A number of systems, going back to the 1960s, have been credited as the first RISC architecture, partly based on their use of
10512-448: The ISA, who in partnership with TI, GEC, Sharp, Nokia, Oracle and Digital would develop low-power and embedded RISC designs, and target those market segments, which at the time were niche. With the rise in mobile, automotive, streaming, smart device computing, ARM became the most widely used ISA, the company estimating almost half of all CPUs shipped in history have been ARM. Confusion around
10658-609: The M8. Much of the processor core development group in Austin, Texas, was dismissed, as were the teams in Santa Clara, California, and Burlington, Massachusetts. Fujitsu will also discontinue their SPARC production (has already shifted to producing their own ARM -based CPUs), after two "enhanced" versions of Fujitsu's older SPARC M12 server in 2020–22 (formerly planned for 2021) and again in 2026–27, end-of-sale in 2029, of UNIX servers and
10804-452: The NZVC condition code bits in the status register , and the other not setting them, with the default being not to set the codes. This is so that the compiler has a way to move instructions around when trying to fill delay slots. If one wants the condition codes to be set, this is indicated by adding cc to the instruction: add and sub also have another modifier, X, which indicates whether
10950-592: The PowerPC have instruction sets as large as the CISC IBM System/370 , for example; conversely, the DEC PDP-8 —clearly a CISC CPU because many of its instructions involve multiple memory accesses—has only 8 basic instructions and a few extended instructions. The term "reduced" in that phrase was intended to describe the fact that the amount of work any single instruction accomplishes is reduced—at most
11096-635: The RESTORE instruction (switching back to the call before returning from the procedure). Trap events ( interrupts , exceptions or TRAP instructions) and RETT instructions (returning from traps) also change the CWP . For SPARC V9, CWP register is decremented during a RESTORE instruction, and incremented during a SAVE instruction. This is the opposite of PSR.CWP's behavior in SPARC V8. This change has no effect on nonprivileged instructions. SPARC registers are shown in
11242-422: The RISC computer is that each instruction performs only one function (e.g. copy a value from memory to a register). The RISC computer usually has many (16 or 32) high-speed, general-purpose registers with a load–store architecture in which the code for the register-register instructions (for performing arithmetic and tests) are separate from the instructions that access the main memory of the computer. The design of
11388-528: The UltraSPARC IV by Sun and the SPARC64 VI by Fujitsu. In early 2006, Sun released an extended architecture specification, UltraSPARC Architecture 2005 . This includes not only the non-privileged and most of the privileged portions of SPARC V9, but also all the architectural extensions developed through the processor generations of UltraSPARC III, IV, and IV+, as well as CMT extensions starting with
11534-535: The VAX. They followed this up with the 40,760-transistor, 39-instruction RISC-II in 1983, which ran over three times as fast as RISC-I. As the RISC project began to become known in Silicon Valley , a similar project began at Stanford University in 1981. This MIPS project grew out of a graduate course by John L. Hennessy , produced a functioning system in 1983, and could run simple programs by 1984. The MIPS approach emphasized an aggressive clock cycle and
11680-441: The analogy of a spring-loaded stack of plates in a cafeteria. Clean plates are placed on top of the stack, pushing down any plates already there. When the top plate is removed from the stack, the one below it is elevated to become the new top plate. In many implementations, a stack has more operations than the essential "push" and "pop" operations. An example of a non-essential operation is "top of stack", or "peek", which observes
11826-415: The application instruction ( load–store ) level or at the memory page level (via an MMU setting). The latter is often used for accessing data from inherently little-endian devices, such as those on PCI buses. There have been three major revisions of the architecture. The first published version was the 32-bit SPARC version 7 (V7) in 1986. SPARC version 8 (V8), an enhanced SPARC architecture definition,
11972-451: The bottom two bits of both operands are 0 and reporting overflow if they are not. This can be useful in the implementation of the run time for ML , Lisp , and similar languages that might use a tagged integer format. The endianness of the 32-bit SPARC V8 architecture is purely big-endian. The 64-bit SPARC V9 architecture uses big-endian instructions, but can access data in either big-endian or little-endian byte order, chosen either at
12118-472: The characteristic of having a branch delay slot , an instruction space immediately following a jump or branch. The instruction in this space is executed, whether or not the branch is taken (in other words the effect of the branch is delayed). This instruction keeps the ALU of the CPU busy for the extra time normally needed to perform a branch. Nowadays the branch delay slot is considered an unfortunate side effect of
12264-454: The completion of memory references. For example, all effects of the stores that appear prior to the MEMBAR instruction must be made visible to all processors before any loads following the MEMBAR can be executed. Arithmetic and logical instructions also use a three-operand format, with the first two being the operands and the last being the location to store the result. The middle operand can be
12410-520: The condition codes and versions that do. MULSCC and the multiply instructions use the Y register to hold the upper 32 bits of the product; the divide instructions use it to hold the upper 32 bits of the dividend. The RDY instruction reads the value of the Y register into a general-purpose register; the WRY instruction writes the value of a general-purpose register to the Y register. SPARC V9 added MULX , which multiplies two 64-bit values and produces
12556-441: The constants in a program would fit in 13 bits , yet many CPU designs dedicated 16 or 32 bits to store them. This suggests that, to reduce the number of memory accesses, a fixed length machine could store constants in unused bits of the instruction word itself, so that they would be immediately ready when the CPU needs them (much like immediate addressing in a conventional design). This required small opcodes in order to leave room for
12702-423: The definition of RISC deriving from the formulation of the term, along with the tendency to opportunistically categorize processor architectures with relatively few instructions (or groups of instructions) as RISC architectures, led to attempts to define RISC as a design philosophy. One attempt to do so was expressed as the following: A RISC processor has an instruction set that is designed for efficient execution by
12848-414: The direction in which the stack grows in memory), pointing it to the next cell, and copies the new top item to the stack area. Depending again on the exact implementation, at the end of a push operation, the stack pointer may point to the next unused location in the stack, or it may point to the topmost item in the stack. If the stack points to the current topmost item, the stack pointer will be updated before
12994-472: The early 1980s, leading, for example, to the iron law of processor performance . Since 2010, a new open standard instruction set architecture (ISA), Berkeley RISC-V , has been under development at the University of California, Berkeley, for research purposes and as a free alternative to proprietary ISAs. As of 2014, version 2 of the user space ISA is fixed. The ISA is designed to be extensible from
13140-408: The figure above. There is also a non-windowed Y register, used by the multiply-step, integer multiply, and integer divide instructions. A SPARC V8 processor with an FPU includes 32 32-bit floating-point registers, each of which can hold one single-precision IEEE 754 floating-point number. An even–odd pair of floating-point registers can hold one double-precision IEEE 754 floating-point number, and
13286-552: The first SPARC V7 implementation in 1987 through the Sun UltraSPARC Architecture implementations. Among various implementations of SPARC, Sun's SuperSPARC and UltraSPARC-I were very popular, and were used as reference systems for SPEC CPU95 and CPU2000 benchmarks. The 296 MHz UltraSPARC-II is the reference system for the SPEC CPU2006 benchmark. SPARC is a load–store architecture (also known as
13432-535: The first such computers, using the Apple M1 processor, were released in November 2020. Macs with Apple silicon can run x86-64 binaries with Rosetta 2 , an x86-64 to ARM64 translator. Outside of the desktop arena, however, the ARM RISC architecture is in widespread use in smartphones, tablets and many forms of embedded devices. While early RISC designs differed significantly from contemporary CISC designs, by 2000
13578-474: The head of the list; overflow is not possible in this implementation (unless memory is exhausted): Some languages, such as Perl , LISP , JavaScript and Python , make the stack operations push and pop available on their standard list/array types. Some languages, notably those in the Forth family (including PostScript ), are designed around language-defined stacks that are directly visible to and manipulated by
13724-458: The highest-performing CPUs in the RISC line were almost indistinguishable from the highest-performing CPUs in the CISC line. RISC architectures are now used across a range of platforms, from smartphones and tablet computers to some of the world's fastest supercomputers such as Fugaku , the fastest on the TOP500 list as of November 2020 , and Summit , Sierra , and Sunway TaihuLight ,
13870-602: The idea of a stack called Operationskeller ("operational cellar") in 1955 and filed a patent in 1957. In March 1988, by which time Samelson was deceased, Bauer received the IEEE Computer Pioneer Award for the invention of the stack principle. Similar concepts were independently developed by Charles Leonard Hamblin in the first half of 1954 and by Wilhelm Kämmerer [ de ] with his automatisches Gedächtnis ("automatic memory") in 1958. Stacks are often described using
14016-413: The immediate value 1. The original RISC-I format remains a canonical example of the concept. It uses 7 bits for the opcode and a 1-bit flag for conditional codes, the following 5 bits for the destination register, and the next five for the first operand. This leaves 14 bits, the first of which indicates whether the following 13 contain an immediate value or uses only five of them to indicate a register for
14162-424: The indicated location and then either fill the rest of the target register with zeros (unsigned load) or with the value of the uppermost bit of the byte or half-word (signed load). During a store, those instructions discard the upper bits in the register and store only the lower bits. There are also instructions for loading double-precision values used for floating-point arithmetic , reading or writing eight bytes from
14308-469: The indicated register and the "next" one, so if the destination of a load is L1, L1 and L2 will be set. The complete list of load and store instructions for the general-purpose registers in 32-bit SPARC is LD , ST , LDUB (unsigned byte), LDSB (signed byte), LDUH (unsigned half-word), LDSH (signed half-word), LDD (load double), STB (store byte), STH (store half-word), STD (store double). In SPARC V9, registers are 64-bit, and
14454-564: The individual instructions given to the computer to accomplish tasks. Compared to the instructions given to a complex instruction set computer (CISC), a RISC computer might require more instructions (more code) in order to accomplish a task because the individual instructions are written in simpler code. The goal is to offset the need to process more instructions by increasing the speed of each instruction, in particular by implementing an instruction pipeline , which may be simpler to achieve given simpler instructions. The key operational concept of
14600-403: The instruction encoding. This leaves ample room to indicate both the opcode and one or two registers. Register-to-register operations, mostly math and logic, require enough bits to encode the two or three registers being used. Most processors use the three-operand format, of the form A = B + C , in which case three registers numbers are needed. If the processor has 32 registers, each one requires
14746-445: The instruction word which could then be used to select among a larger set of registers. The telephone switch program was canceled in 1975, but by then the team had demonstrated that the same design would offer significant performance gains running just about any code. In simulations, they showed that a compiler tuned to use registers wherever possible would run code about three times as fast as traditional designs. Somewhat surprisingly,
14892-491: The integer condition codes and from each other; two additional sets of branch instructions were defined to test those condition codes. Adding an F to the front of the branch instruction in the list above performs the test against the FPU's condition codes, while, in SPARC V8, adding a C tests the flags in the otherwise undefined CP. The CALL (jump to subroutine) instruction uses a 30-bit program counter -relative word offset. As
15038-592: The introduction of similar RISC designs from many vendors through the 1980s and 1990s. The first implementation of the original 32-bit architecture (SPARC V7) was used in Sun's Sun-4 computer workstation and server systems, replacing their earlier Sun-3 systems based on the Motorola 68000 series of processors. SPARC V8 added a number of improvements that were part of the SuperSPARC series of processors released in 1992. SPARC V9, released in 1993, introduced
15184-428: The large variety of instructions in the 68k. Patterson's early work pointed out an important problem with the traditional "more is better" approach; even those instructions that were critical to overall performance were being delayed by their trip through the microcode. If the microcode was removed, the programs would run faster. And since the microcode ultimately took a complex instruction and broke it into steps, there
15330-482: The late 1970s, the 801 had become well-known in the industry. This coincided with new fabrication techniques that were allowing more complex chips to come to market. The Zilog Z80 of 1976 had 8,000 transistors, whereas the 1979 Motorola 68000 (68k) had 68,000. These newer designs generally used their newfound complexity to expand the instruction set to make it more orthogonal. Most, like the 68k, used microcode to do this, reading instructions and re-implementing them as
15476-405: The local registers are used for retaining local values across function calls. The "scalable" in SPARC comes from the fact that the SPARC specification allows implementations to scale from embedded processors up through large server processors, all sharing the same core (non-privileged) instruction set. One of the architectural parameters that can scale is the number of implemented register windows;
15622-722: The lower bits. The new LDX instruction loads a 64-bit value into the register, and the STX instruction stores all 64 bits of the register. The LDF , LDDF , and LDQF instructions load a single-precision, double-precision, or quad-precision value from memory into a floating-point register; the STF , STDF , and STQF instructions store a single-precision, double-precision, or quad-precision floating-point register into memory. The memory barrier instruction, MEMBAR, serves two interrelated purposes: it articulates order constraints among memory references and facilitates explicit control over
15768-494: The main goals of the RISC approach. Some of this is possible only due to the contemporary move to 32-bit formats. For instance, in a typical program, over 30% of all the numeric constants are either 0 or 1, 95% will fit in one byte, and 99% in a 16-bit value. When computers were based on 8- or 16-bit words, it would be difficult to have an immediate combined with the opcode in a single memory word, although certain instructions like increment and decrement did this implicitly by using
15914-422: The majority of mathematical instructions were simple assignments; only 1 ⁄ 3 of them actually performed an operation like addition or subtraction. But when those operations did occur, they tended to be slow. This led to far more emphasis on the underlying arithmetic data unit, as opposed to previous designs where the majority of the chip was dedicated to control and microcode. The resulting Berkeley RISC
16060-408: The maximum extent of the stack, a stack overflow occurs. Some environments that rely heavily on stacks may provide additional operations, for example: Stacks are often visualized growing from the bottom up (like real-world stacks). They may also be visualized growing from left to right, where the top is on the far right, or even growing from top to bottom. The important feature is for the bottom of
16206-512: The memory access time. Partly due to the optimized load–store architecture of the CDC 6600, Jack Dongarra says that it can be considered a forerunner of modern RISC systems, although a number of other technical barriers needed to be overcome for the development of a modern RISC system. Michael J. Flynn views the first RISC system as the IBM 801 design, begun in 1975 by John Cocke and completed in 1980. The 801 developed out of an effort to build
16352-558: The mid-1980s. The Acorn ARM1 appeared in April 1985, MIPS R2000 appeared in January 1986, followed shortly thereafter by Hewlett-Packard 's PA-RISC in some of their computers. In the meantime, the Berkeley effort had become so well known that it eventually became the name for the entire concept. In 1987 Sun Microsystems began shipping systems with the SPARC processor, directly based on
16498-563: The most significant characteristics of RISC processors was that external memory was only accessible by a load or store instruction. All other instructions were limited to internal registers. This simplified many aspects of processor design: allowing instructions to be fixed-length, simplifying pipelines, and isolating the logic for dealing with the delay in completing a memory access (cache miss, etc.) to only two instructions. This led to RISC designs being referred to as load–store architectures. Some CPUs have been specifically designed to have
16644-657: The most widely adopted RISC ISA, initially intended to deliver higher-performance desktop computing, at low cost, and in a restricted thermal package, such as in the Acorn Archimedes , while featuring in the Super Computer League tables , its initial, relatively, lower power and cooling implementation was soon adapted to embedded applications, such as laser printer raster image processing. Acorn, in partnership with Apple Inc, and VLSI, creating ARM Ltd, in 1990, to share R&D costs and find new markets for
16790-402: The next three on that list. Stack (abstract data type) In computer science , a stack is an abstract data type that serves as a collection of elements with two main operations: Additionally, a peek operation can, without modifying the stack, return the value of the last element added. The name stack is an analogy to a set of physical items stacked one atop another, such as
16936-540: The opcode was 0 and the last 6 bits contained the actual code; those that used an immediate value used the normal opcode field at the front. One drawback of 32-bit instructions is reduced code density, which is more adverse a characteristic in embedded computing than it is in the workstation and server markets RISC architectures were originally designed to serve. To address this problem, several architectures, such as SuperH (1992), ARM thumb (1994), MIPS16e (2004), Power Variable Length Encoding ISA (2006), RISC-V , and
17082-530: The operation should set the carry bit: SPARC V7 does not have multiplication or division instructions, but it does have MULSCC , which does one step of a multiplication testing one bit and conditionally adding the multiplicand to the product. This was because MULSCC can complete over one clock cycle in keeping with the RISC philosophy. SPARC V8 added UMUL (unsigned multiply), SMUL (signed multiply), UDIV (unsigned divide), and SDIV (signed divide) instructions, with both versions that do not update
17228-531: The opposite direction, having added longer 32-bit instructions to an original 16-bit encoding. The most characteristic aspect of RISC is executing at least one instruction per cycle . Single-cycle operation is described as "the rapid execution of simple functions that dominate a computer's instruction stream", thus seeking to deliver an average throughput approaching one instruction per cycle for any single instruction stream. Other features of RISC architectures include: RISC designs are also more likely to feature
17374-435: The origin of the stack. In other words, if the origin of the stack is at address 1000 and the stack grows downwards (towards addresses 999, 998, and so on), the stack pointer must never be incremented beyond 1000 (to 1001 or beyond). If a pop operation on the stack causes the stack pointer to move past the origin of the stack, a stack underflow occurs. If a push operation causes the stack pointer to increment or decrement beyond
17520-419: The program to fail. Malicious parties may attempt a stack smashing attack that takes advantage of this type of implementation by providing oversized data input to a program that does not check the length of input. Such a program may copy the data in its entirety to a location on the stack, and in doing so, it may change the return addresses for procedures that have called it. An attacker can experiment to find
17666-601: The programmer. The following is an example of manipulating a stack in Common Lisp (" > " is the Lisp interpreter's prompt; lines not starting with " > " are the interpreter's responses to expressions): Several of the C++ Standard Library container types have push_back and pop_back operations with LIFO semantics; additionally, the stack template class adapts existing containers to provide
17812-584: The register file is not part of the architecture, allowing more registers to be added as the technology improves, up to a maximum of 32 windows in SPARC V7 and V8 as CWP is 5 bits and is part of the PSR register. In SPARC V7 and V8 CWP will usually be decremented by the SAVE instruction (used by the SAVE instruction during the procedure call to open a new stack frame and switch the register window), or incremented by
17958-497: The required additional memory accesses. It was argued that such functions would be better performed by sequences of simpler instructions if this could yield implementations small enough to leave room for many registers, reducing the number of slow memory accesses. In these simple designs, most instructions are of uniform length and similar structure, arithmetic operations are restricted to CPU registers and only separate load and store instructions access memory. These properties enable
18104-402: The resulting machine being called a "reduced instruction set computer" (RISC). The goal was to make instructions so simple that they could easily be pipelined, in order to achieve a single clock throughput at high frequencies . This contrasted with CISC designs whose "crucial arithmetic operations and register transfers" were considered difficult to pipeline. Later, it was noted that one of
18250-508: The same code would run about 50% faster even on existing machines due to the improved register use. In practice, their experimental PL/8 compiler, a slightly cut-down version of PL/I , consistently produced code that ran much faster on their existing mainframes. A 32-bit version of the 801 was eventually produced in a single-chip form as the IBM ROMP in 1981, which stood for 'Research OPD [Office Products Division] Micro Processor'. This CPU
18396-682: The same stack for both data and procedure calls has important security implications ( see below ) of which a programmer must be aware in order to avoid introducing serious security bugs into a program. Several algorithms use a stack (separate from the usual function call stack of most programming languages) as the principal data structure with which they organize their information. These include: Some computing environments use stacks in ways that may make them vulnerable to security breaches and attacks. Programmers working in such environments must take special care to avoid such pitfalls in these implementations. As an example, some programming languages use
18542-475: The second half of the 1980s, and led the designers of the MIPS-X to put it this way in 1987: The goal of any instruction format should be: 1. simple decode, 2. simple decode, and 3. simple decode. Any attempts at improved code density at the expense of CPU performance should be ridiculed at every opportunity. Competition between RISC and conventional CISC approaches was also the subject of theoretical analysis in
18688-408: The second operand. A more complex example is the MIPS encoding, which used only 6 bits for the opcode, followed by two 5-bit registers. The remaining 16 bits could be used in two ways, one as a 16-bit immediate value, or as a 5-bit shift value (used only in shift operations, otherwise zero) and the remaining 6 bits as an extension on the opcode. In the case of register-to-register arithmetic operations,
18834-560: The specification allows from three to 32 windows to be implemented, so the implementation can choose to implement all 32 to provide maximum call stack efficiency, or to implement only three to reduce cost and complexity of the design, or to implement some number between them. Other architectures that include similar register file features include Intel i960 , IA-64 , and AMD 29000 . The architecture has gone through several revisions. It gained hardware multiply and divide functionality in version 8. 64-bit (addressing and data) were added to
18980-433: The stack is simply the size of the dynamic array, which is a very efficient implementation of a stack since adding items to or removing items from the end of a dynamic array requires amortized O(1) time. Another option for implementing stacks is to use a singly linked list . A stack is then a pointer to the "head" of the list, with perhaps a counter to keep track of the size of the list: Pushing and popping items happens at
19126-425: The stack itself can be effectively implemented as a three-element structure: The push operation adds an element and increments the top index, after checking for overflow: Similarly, pop decrements the top index after checking for underflow, and returns the item that was previously the top one: Using a dynamic array , it is possible to implement a stack that can grow or shrink as much as needed. The size of
19272-417: The stack to be in a fixed position. The illustration in this section is an example of a top-to-bottom growth visualization: the top (28) is the stack "bottom", since the stack "top" (9) is where items are pushed or popped from. A right rotate will move the first element to the third position, the second to the first and the third to the second. Here are two equivalent visualizations of this process: A stack
19418-431: The target address is specifying the start of a word, not a byte, 30-bits is all that is needed to reach any address in the 4 gigabyte address space. The CALL instruction deposits the return address in register R15, also known as output register O7. Reduced instruction set computer In electronics and computer science , a reduced instruction set computer ( RISC ) is a computer architecture designed to simplify
19564-496: The top element without removing it from the stack. Since this can be broken down into a "pop" followed by a "push" to return the same data to the stack, it is not considered an essential operation. If the stack is empty, an underflow condition will occur upon execution of either the "stack top" or "pop" operations. Additionally, many implementations provide a check if the stack is empty and an operation that returns its size. A stack can be easily implemented either through an array or
19710-459: The use of memory; a single instruction from a traditional processor like the Motorola 68k may be written out as perhaps a half dozen of the simpler RISC instructions. In theory, this could slow the system down as it spent more time fetching instructions from memory. But by the mid-1980s, the concepts had matured enough to be seen as commercially viable. Commercial RISC designs began to emerge in
19856-649: The use of slow main memory for function arguments and return values. There is also a number of small microprocessors that implement a stack directly in hardware, and some microcontrollers have a fixed-depth stack that is not directly accessible. Examples are the PIC microcontrollers , the Computer Cowboys MuP21 , the Harris RTX line, and the Novix NC4016 . At least one microcontroller family,
20002-514: The use of the pipeline, making sure it could be run as "full" as possible. The MIPS system was followed by the MIPS-X and in 1984 Hennessy and his colleagues formed MIPS Computer Systems to produce the design commercially. The venture resulted in a new architecture that was also called MIPS and the R2000 microprocessor in 1985. The overall philosophy of the RISC concept was widely understood by
20148-441: The vast majority of the available instructions, especially orthogonal addressing modes. Instead, they selected the fastest version of any given instruction and then constructed small routines using it. This suggested that the majority of instructions could be removed without affecting the resulting code. These two conclusions worked in concert; removing instructions would allow the instruction opcodes to be shorter, freeing up bits in
20294-765: The version 9 SPARC specification published in 1994. In SPARC version 8, the floating-point register file has 16 double-precision registers. Each of them can be used as two single-precision registers, providing a total of 32 single-precision registers. An odd–even number pair of double-precision registers can be used as a quad-precision register, thus allowing 8 quad-precision registers. SPARC Version 9 added 16 more double-precision registers (which can also be accessed as 8 quad-precision registers), but these additional registers can not be accessed as single-precision registers. No SPARC CPU implements quad-precision operations in hardware as of 2024. Tagged add and subtract instructions perform adds and subtracts on values checking that
20440-495: The window "down" by eight, to the set of eight registers used by that procedure, and the return moves the window back. The Berkeley RISC project delivered the RISC-I processor in 1982. Consisting of only 44,420 transistors (compared with averages of about 100,000 in newer CISC designs of the era), RISC-I had only 32 instructions, and yet completely outperformed any other single-chip design, with estimated performance being higher than
20586-498: Was based on gaining performance through the use of pipelining and aggressive use of register windowing. In a traditional CPU, one has a small number of registers, and a program can use any register at any time. In a CPU with register windows, there are a huge number of registers, e.g., 128, but programs can only use a small number of them, e.g., eight, at any one time. A program that limits itself to eight registers per procedure can make very fast procedure calls : The call simply moves
20732-468: Was designed for "mini" tasks, and found use in peripheral interfaces and channel controllers on later IBM computers. It was also used as the CPU in the IBM RT PC in 1986, which turned out to be a commercial failure. Although the 801 did not see widespread use in its original form, it inspired many research projects, including ones at IBM that would eventually lead to the IBM POWER architecture . By
20878-474: Was no reason the compiler couldn't do this instead. These studies suggested that, even with no other changes, one could make a chip with 1 ⁄ 3 fewer transistors that would run faster. In the original RISC-I paper they noted: Skipping this extra level of interpretation appears to enhance performance while reducing chip size. It was also discovered that, on microcoded implementations of certain architectures, complex operations tended to be slower than
21024-629: Was released by Fujitsu and Sun, describing processor functions which were identically implemented in the CPUs of both companies ("Commonality"). The first CPUs conforming to JPS1 were the UltraSPARC III by Sun and the SPARC64 V by Fujitsu. Functionalities which are not covered by JPS1 are documented for each processor in "Implementation Supplements". At the end of 2003, JPS2 was released to support multicore CPUs. The first CPUs conforming to JPS2 were
21170-587: Was released by SPARC International in 1993. It was developed by the SPARC Architecture Committee consisting of Amdahl Corporation , Fujitsu , ICL , LSI Logic , Matsushita , Philips , Ross Technology , Sun Microsystems , and Texas Instruments . Newer specifications always remain compliant with the full SPARC V9 Level 1 specification. In 2002, the SPARC Joint Programming Specification 1 (JPS1)
21316-412: Was released in 1990. The main differences between V7 and V8 were the addition of integer multiply and divide instructions, and an upgrade from 80-bit "extended-precision" floating-point arithmetic to 128-bit " quad-precision " arithmetic. SPARC V8 served as the basis for IEEE Standard 1754-1994, an IEEE standard for a 32-bit microprocessor architecture. SPARC version 9 , the 64-bit SPARC architecture,
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