DOCSLIB.ORG

CISC Developments Overview CISC Designs RISC Designs Digital VAX VAX: Addressing Modes

Total Page：16

File Type：pdf, Size：1020Kb

Download full-text PDF Read full-text
CISC Developments Overview CISC Designs RISC Designs Digital VAX VAX: Addressing Modes Overview • Classic CISC design: Digital VAX CISC Developments • VAX’s RISC successor: PRISM/Alpha • Intel’s ubiquitous 80x86 architecture Over Twenty Years – 8086 through the Pentium Pro (P6) RJS 2/3/97 CISC Designs RISC Designs • Philosophy • Philosophy – Reduce code size – Simple, quick instructions. – Machine language should match the semantics • Results of high level language constructs – Instruction dependencies can be easily • Results determined. – Complicated instructions which could take – Instructions can be sub-divided and pipelined. many cycles to execute – High instruction throughput. Digital VAX VAX: Addressing Modes • Mid-70’s design Register r4 – 32-bit architecture Base (displacement) [r4 + offset] – Basically a general-purpose register machine Immediate 0xFFF0101 • CISC philosophy PC-relative [PC] + offset – Numerous addressing modes – Rich instruction suite Deferred (indirect) [ [r3 + offset] ] Index (scaled) [r3 + r4 * 8] VAX: Addt’l Addressing Modes VAX: Instruction Encoding • Byte, word, double word displacement • Operations: 1 byte • Auto-increment/auto-decrement • Each operand must be encoded to specify – Acesses memory and then increments/ the addressing mode decrements address • Example: – Integer add: 3-19 bytes VAX: Instructions CISC: Side effects • Push • Instruction basically has multiple results – Push an item onto a stack – Auto-increment • insque • combines a load/store with an addition – Insert an item onto a queue – Condition codes • Negative, Zero, oVerflow, Carry • aobleq op1 op2 • Arithmetic instructions set these codes – Add one to op1 and branch if equal to op2 • Codes are used for conditional branches • Special call/ret – Handles argument, stack setup automatically Digital: Beyond VAX INTEL • PRISM/Alpha • 1978: 8086 – RISC processor – 16-bit, extended accumulator machine • fixed size instructions • 1982: 80286 backward compatible • load/store architecture – 24-bit address space • out-of-order execution • speculation • 1985: 80386 backward compatible • Backward Compatibility? – 32-bit address space – Recompilation: VAX --> Alphas • 1992: Pentium backward compatible • 1996: P6 backward compatible 80x86: Overview 80x86: Segmented Addr Space • Has moved closer to a general purpose • Real Mode (8086) register machine – Segment register is shift to the left 4 bits and • Segmented address space the offet is added. • Instructions work on bytes, words, double • Protected Mode (80286) words. – Segment register selects an index into the segment address table. (24 bits) Offset is added. • Only four instructions added since 1989. • Protected Mode (80386, 80486, Pentium) – Three multiprocessing instructions – Segment descriptor is 32 bits. – One conditional move 80x86: Addressing Modes 80x86: Instruction Complications Absolute [0xa0000000] • Instruction prefixes [r4] Register – Override default data size, segment registers Based displacement [r4 + offset] – Lock the bus (i.e synchronization) Indexed [r3 + r4] – Repeat instruction until register CX counts to Based indexed [r3 + r4 + offset] zero. Base plus scaled index [r3 + r4 * scale] • Multiple segments complicate control-flow Base scaled [r3 + r4 * scale + offset] statements displacement 80x86: Instruction Usage Intel: Improving CISC • Instructions: 1 to 17 bytes • Pentium: Leveraged RISC technology – Integer programs: av=2.8 – 5-stage pipeline – Floating point programs: av=4.1 – Dual-issue • Most frequent addressing modes: Based – No branch prediction displacement and Based scaled indexing. – No out-of-order execution • Software basically needs recompilation Pentium Pro (P6) P6: Pipeline Stages 1 -4 • A RISC processor running a CISC • Stage 1 instruction set. – Determines next PC – Three way issue • Stage 2-4 – Speculative execution – Fetch and mark instruction – out-of-order execution • Superscalar pipeline – Allows higher clock rate while handling CISC P6: Pipeline Stages 5-6 P6: Pipeline Stages 7-8 • Instruction is decoded into a series of • Assign logical registers to physical registers micro-ops (uops) – 80x86 machine instructions are limited to the – Three decoders basic x86 registers. • Two decoders handle simple instructions – x86 architecture has 16 physical registers • Third decoder handles more complex cases – P6 has 40 physical registers • Falls through decoder to a special microcode area • Prepared uops are passed to the reservation – Majority translate to < 4 uops. station and reorder buffer – Worst case: 204 uops P6: Pipeline Stages 9-10 P6: Pipeline Stage 11 • Reservation station dispatches uops to one • Execution of five parallel execution units. – May overlap into stage 12 – Two integer, one load, one store, and one FPU • Reorder buffer holds the uops – Status flags signal dependencies P6: Pipeline Stages 12-14 P6: Pipeline Performance • Instructions are retired • 80x86 references memory more often than a – Must wait until all uops that comprise the typical RISC instruction set. instruction are complete – Floating point programs: 2-4x higher – Must handle precise exceptions – Integer programs: 1.25 higher • Superpipelining and branch prediction problems. – P6 uses 4-bit branch history P6: Completely RISC? References • Can a compiler directly generate uops? • Hennesy and Patterson, “Computer Organization – Bypass decoding phase and Design: The Hardware/Software Interface” – Leverage static scheduling techniques • Hennesy and Patterson, “Computer Architecture: A Quantitative Approach” – Force competing chip makers to use same basic design. • Bhandarkar, “Alpha Implementations and Architecture” • Could reduce differentiating points between competitors. • Byte, April 1995, “Intel’s P6” • http://www.intel/procs/ppro/info/isscc/index.htm.
Load more

Recommended publications
  • PERL – a Register-Less Processor
    PERL { A Register-Less Processor A Thesis Submitted in Partial Fulfillment of the Requirements for the Degree of Doctor of Philosophy by P. Suresh to the Department of Computer Science & Engineering Indian Institute of Technology, Kanpur February, 2004 Certificate Certified that the work contained in the thesis entitled \PERL { A Register-Less Processor", by Mr.P. Suresh, has been carried out under my supervision and that this work has not been submitted elsewhere for a degree. (Dr. Rajat Moona) Professor, Department of Computer Science & Engineering, Indian Institute of Technology, Kanpur. February, 2004 ii Synopsis Computer architecture designs are influenced historically by three factors: market (users), software and hardware methods, and technology. Advances in fabrication technology are the most dominant factor among them. The performance of a proces- sor is defined by a judicious blend of processor architecture, efficient compiler tech- nology, and effective VLSI implementation. The choices for each of these strongly depend on the technology available for the others. Significant gains in the perfor- mance of processors are made due to the ever-improving fabrication technology that made it possible to incorporate architectural novelties such as pipelining, multiple instruction issue, on-chip caches, registers, branch prediction, etc. To supplement these architectural novelties, suitable compiler techniques extract performance by instruction scheduling, code and data placement and other optimizations. The performance of a computer system is directly related to the time it takes to execute programs, usually known as execution time. The expression for execution time (T), is expressed as a product of the number of instructions executed (N), the average number of machine cycles needed to execute one instruction (Cycles Per Instruction or CPI), and the clock cycle time (), as given in equation 1.
    [Show full text]
  • Mi!!Lxlosalamos SCIENTIFIC LABORATORY
    LA=8902-MS C3b ClC-l 4 REPORT COLLECTION REPRODUCTION COPY VAXNMS Benchmarking 1-’ > .— u) 9 g .— mi!!lxLOS ALAMOS SCIENTIFIC LABORATORY Post Office Box 1663 Los Alamos. New Mexico 87545 — wAifiimative Action/Equal Opportunity Employer b . l)lS(”L,\l\ll K “Thisreport wm prcpmd J, an xcttunt ,,1”wurk ,pmwrd by an dgmcy d the tlnitwl SIdtcs (kvcm. mm:. Ncit her t hc llniml SIJIL.. ( Lwcrnmcm nor any .gcncy tlhmd. nor my 08”Ihcif cmployccs. makci my wur,nly. mprcss w mphd. or JwImL.s m> lcg.d Iululity ur rcspmuhdily ltw Ilw w.cur- acy. .vmplctcncs. w uscftthtc>. ttt”any ml’ormdt ml. dpprdl us. prudu.i. w proccw didowd. or rep. resent%Ihd IIS us wuukl not mfrm$e priwtcly mvnd rqdtts. Itcl”crmcti herein 10 my sp.xi!l tom. mrcial ptotlucr. prtxcm. or S.rvskc hy tdc mmw. Irdcnmrl.. nmu(a.lurm. or dwrwi~.. does nut mmwsuily mnstitutc or reply its mdursmwnt. rccummcnddton. or favorin: by the llniwd States (“mvcmment ormy qxncy thctcd. rhc V!C$VSmd opinmm d .mthor% qmxd herein do nut net’. UMrily r;~lt or died lhow. ol”the llnttcd SIJIL.S( ;ovwnnwnt or my ugcncy lhure of. UNITED STATES .. DEPARTMENT OF ENERGY CONTRACT W-7405 -ENG. 36 . ... LA-8902-MS UC-32 Issued: July 1981 G- . VAX/VMS Benchmarking Larry Creel —. I . .._- -- ----- ,. .- .-. .: .- ,.. .. ., ..,..: , .. .., . ... ..... - .-, ..:. .. *._–: - . VAX/VMS BENCHMARKING by Larry Creel ABSTRACT Primary emphasis in this report is on the perform- ance of three Digital Equipment Corporation VAX-11/780 computers at the Los Alamos National Laboratory. Programs used in the study are part of the Laboratory’s set of benchmark programs.
    [Show full text]
  • Computer Architecture Basics
    V03: Computer Architecture Basics Prof. Dr. Anton Gunzinger Supercomputing Systems AG Technoparkstrasse 1 8005 Zürich Telefon: 043 – 456 16 00 Email: [email protected] Web: www.scs.ch Supercomputing Systems AG Phone +41 43 456 16 00 Technopark 1 Fax +41 43 456 16 10 8005 Zürich www.scs.ch Computer Architecture Basic 1. Basic Computer Architecture Diagram 2. Basic Computer Architectures 3. Von Neumann versus Harvard Architecture 4. Computer Performance Measurement 5. Technology Trends 2 Zürich 20.09.2019 © by Supercomputing Systems AG CONFIDENTIAL 1.1 Basic Computer Architecture Diagram Sketch the basic computer architecture diagram Describe the functions of the building blocks 3 Zürich 20.09.2019 © by Supercomputing Systems AG CONFIDENTIAL 1.2 Basic Computer Architecture Diagram Describe the execution of a single instruction 5 Zürich 20.09.2019 © by Supercomputing Systems AG CONFIDENTIAL 2 Basic Computer Architecture 2.1 Sketch an Accumulator Machine 2.2 Sketch a Register Machine 2.3 Sketch a Stack Machine 2.4 Sketch the analysis of computing expression in a Stack Machine 2.5 Write the micro program for an Accumulator, a Register and a Stack Machine for the instruction: C:= A + B and estimate the numbers of cycles 2.6 Write the micro program for an Accumulator, a Register and a Stack Machine for the instruction: C:= (A - B)2 + C and estimate the numbers of cycles 2.7 Compare Accumulator, Register and Stack Machine 7 Zürich 20.09.2019 © by Supercomputing Systems AG CONFIDENTIAL 2.1 Accumulator Machine Draw the Accumulator Machine 8 Zürich
    [Show full text]
  • Computers, Complexity, and Controversy
    Instruction Sets and Beyond: Computers, Complexity, and Controversy Robert P. Colwell, Charles Y. Hitchcock m, E. Douglas Jensen, H. M. Brinkley Sprunt, and Charles P. Kollar Carnegie-Mellon University t alanc o tyreceived Instruction set design is important, but lt1Mthi it should not be driven solely by adher- ence to convictions about design style, ,,tl ica' ch m e n RISC or CISC. The focus ofdiscussion o09 Fy ipt issues. RISC should be on the more general question of the assignment of system function- have guided ality to implementation levels within years. A study of an architecture. This point of view en- d yield a deeper un- compasses the instruction set-CISCs f hardware/software tend to install functionality at lower mputer performance, the system levels than RISCs-but also JOCUS on rne assignment iluence of VLSI on processor design, takes into account other design fea- ofsystem functionality to and many other topics. Articles on tures such as register sets, coproces- RISC research, however, often fail to sors, and caches. implementation levels explore these topics properly and can While the implications of RISC re- within an architecture, be misleading. Further, the few papers search extend beyond the instruction and not be guided by that present comparisons with com- set, even within the instruction set do- whether it is a RISC plex instruction set computer design main, there are limitations that have or CISC design. often do not address the same issues. not been identified. Typical RISC As a result, even careful study of the papers give few clues about where the literature is likely to give a distorted RISC approach might break down.
    [Show full text]
  • Programmable Digital Microcircuits - a Survey with Examples of Use
    - 237 - PROGRAMMABLE DIGITAL MICROCIRCUITS - A SURVEY WITH EXAMPLES OF USE C. Verkerk CERN, Geneva, Switzerland 1. Introduction For most readers the title of these lecture notes will evoke microprocessors. The fixed instruction set microprocessors are however not the only programmable digital mi• crocircuits and, although a number of pages will be dedicated to them, the aim of these notes is also to draw attention to other useful microcircuits. A complete survey of programmable circuits would fill several books and a selection had therefore to be made. The choice has rather been to treat a variety of devices than to give an in- depth treatment of a particular circuit. The selected devices have all found useful ap• plications in high-energy physics, or hold promise for future use. The microprocessor is very young : just over eleven years. An advertisement, an• nouncing a new era of integrated electronics, and which appeared in the November 15, 1971 issue of Electronics News, is generally considered its birth-certificate. The adver• tisement was for the Intel 4004 and its three support chips. The history leading to this announcement merits to be recalled. Intel, then a very young company, was working on the design of a chip-set for a high-performance calculator, for and in collaboration with a Japanese firm, Busicom. One of the Intel engineers found the Busicom design of 9 different chips too complicated and tried to find a more general and programmable solu• tion. His design, the 4004 microprocessor, was finally adapted by Busicom, and after further négociation, Intel acquired marketing rights for its new invention.
    [Show full text]
  • ABSTRACT Virtualizing Register Context
    ABSTRACT Virtualizing Register Context by David W. Oehmke Chair: Trevor N. Mudge A processor designer may wish for an implementation to support multiple reg- ister contexts for several reasons: to support multithreading, to reduce context switch overhead, or to reduce procedure call/return overhead by using register windows. Conventional designs require that each active context be present in its entirety, increasing the size of the register file. Unfortunately, larger register files are inherently slower to access and may lead to a slower cycle time or additional cycles of register access latency, either of which reduces overall performance. We seek to bypass the trade-off between multiple context support and register file size by mapping registers to memory, thereby decoupling the logical register requirements of active contexts from the contents of the physical register file. Just as caches and virtual memory allow a processor to give the illusion of numerous multi-gigabyte address spaces with an average access time approach- ing that of several kilobytes of SRAM, we propose an architecture that gives the illusion of numerous active contexts with an average access time approaching that of a single active context using a conventionally sized register file. This dis- sertation introduces the virtual context architecture, a new architecture that virtual- izes logical register contexts. Complete contexts, whether activation records or threads, are kept in memory and are no longer required to reside in their entirety in the physical register file. Instead, the physical register file is treated as a cache of the much larger memory-mapped logical register space. The implementation modifies the rename stage of the pipeline to trigger the movement of register val- ues between the physical register file and the data cache.
    [Show full text]
  • A Characterization of Processor Performance in the VAX-1 L/780
    A Characterization of Processor Performance in the VAX-1 l/780 Joel S. Emer Douglas W. Clark Digital Equipment Corp. Digital Equipment Corp. 77 Reed Road 295 Foster Street Hudson, MA 01749 Littleton, MA 01460 ABSTRACT effect of many architectural and implementation features. This paper reports the results of a study of VAX- llR80 processor performance using a novel hardware Prior related work includes studies of opcode monitoring technique. A micro-PC histogram frequency and other features of instruction- monitor was buiit for these measurements. It kee s a processing [lo. 11,15,161; some studies report timing count of the number of microcode cycles execute z( at Information as well [l, 4,121. each microcode location. Measurement ex eriments were performed on live timesharing wor i loads as After describing our methods and workloads in well as on synthetic workloads of several types. The Section 2, we will re ort the frequencies of various histogram counts allow the calculation of the processor events in 5 ections 3 and 4. Section 5 frequency of various architectural events, such as the resents the complete, detailed timing results, and frequency of different types of opcodes and operand !!Iection 6 concludes the paper. specifiers, as well as the frequency of some im lementation-s ecific events, such as translation bu h er misses. ?phe measurement technique also yields the amount of processing time spent, in various 2. DEFINITIONS AND METHODS activities, such as ordinary microcode computation, memory management, and processor stalls of 2.1 VAX-l l/780 Structure different kinds. This paper reports in detail the amount of time the “average’ VAX instruction The llf780 processor is composed of two major spends in these activities.
    [Show full text]
  • Turing Machines [Fa’16]
    Models of Computation Lecture 6: Turing Machines [Fa’16] Think globally, act locally. — Attributed to Patrick Geddes (c.1915), among many others. We can only see a short distance ahead, but we can see plenty there that needs to be done. — Alan Turing, “Computing Machinery and Intelligence” (1950) Never worry about theory as long as the machinery does what it’s supposed to do. — Robert Anson Heinlein, Waldo & Magic, Inc. (1950) It is a sobering thought that when Mozart was my age, he had been dead for two years. — Tom Lehrer, introduction to “Alma”, That Was the Year That Was (1965) 6 Turing Machines In 1936, a few months before his 24th birthday, Alan Turing launched computer science as a modern intellectual discipline. In a single remarkable paper, Turing provided the following results: • A simple formal model of mechanical computation now known as Turing machines. • A description of a single universal machine that can be used to compute any function computable by any other Turing machine. • A proof that no Turing machine can solve the halting problem—Given the formal description of an arbitrary Turing machine M, does M halt or run forever? • A proof that no Turing machine can determine whether an arbitrary given proposition is provable from the axioms of first-order logic. This is Hilbert and Ackermann’s famous Entscheidungsproblem (“decision problem”). • Compelling arguments1 that his machines can execute arbitrary “calculation by finite means”. Although Turing did not know it at the time, he was not the first to prove that the Entschei- dungsproblem had no algorithmic solution.
    [Show full text]
  • Chapter 5 the LC-3
    Instruction Set Architecture ISA = Programmer-visible components & operations • Memory organization Address space -- how may locations can be addressed? Addressibility -- how many bits per location? • Register set Chapter 5 How many? What size? How are they used? • Instruction set The LC-3 Opcodes Data types Addressing modes All information needed to write/gen machine language program Based on slides © McGraw-Hill Additional material © 2004/2005 Lewis/Martin CSE 240 5-2 LC-3 Overview: Memory and Registers LC-3 Overview: Instruction Set Memory Opcodes • Address space: 216 locations (16-bit addresses) • 16 opcodes • Addressibility: 16 bits • Operate instructions: ADD, AND, NOT, (MUL) • Data movement instructions: LD, LDI, LDR, LEA, ST, STR, STI Registers • Control instructions: BR, JSR, JSRR, RET, RTI, TRAP • Temporary storage, accessed in a single machine cycle • Some opcodes set/clear condition codes, based on result Memory access generally takes longer N = negative (<0), Z = zero (=0), P = positive (> 0) • Eight general-purpose registers: R0 - R7 Data Types Each 16 bits wide • 16-bit 2’s complement integer How many bits to uniquely identify a register? Addressing Modes • Other registers • How is the location of an operand specified? Not directly addressable, but used by (and affected by) • Non-memory addresses: register, immediate (literal) instructions PC (program counter), condition codes, MAR, MDR, etc. • Memory addresses: base+offset, PC-relative, indirect CSE 240 5-3 CSE 240 5-4 1 LC-3 Instruction Summary Operate Instructions (inside back cover) Only three operations • ADD, AND, NOT Source and destination operands are registers • Do not reference memory • ADD and AND can use “immediate” mode, (i.e., one operand is hard-wired into instruction) Will show abstracted datapath with each instruction • Illustrate when and where data moves to accomplish desired op.
    [Show full text]
  • Instruction Set Architecture
    Instruction Set Architecture EE3376 1 –Adapted from notes from BYU ECE124 Topics to Cover… l MSP430 ISA l MSP430 Registers, ALU, Memory l Instruction Formats l Addressing Modes l Double Operand Instructions l Single Operand Instructions l Jump Instructions l Emulated Instructions – http://en.wikipedia.org/wiki/TI_MSP430 2 –Adapted from notes from BYU ECE124 Levels of Transformation –Problems –Algorithms – C Instructions –Language (Program) –Programmable –Assembly Language – MSP 430 ISA –Machine (ISA) Architecture –Computer Specific –Microarchitecture –Manufacturer Specific –Circuits –Devices 3 –Adapted from notes from BYU ECE124 Instruction Set Architecture l The computer ISA defines all of the programmer-visible components and operations of the computer – memory organization l address space -- how may locations can be addressed? l addressibility -- how many bits per location? – register set (a place to store a collection of bits) l how many? what size? how are they used? – instruction set l Opcodes (operation selection codes) l data types (data types: byte or word) l addressing modes (coding schemes to access data) l ISA provides all information needed for someone that wants to write a program in machine language (or translate 4 from a high-level language to machine language). –Adapted from notes from BYU ECE124 MSP430 Instruction Set Architecture l MSP430 CPU specifically designed to allow the use of modern programming techniques, such as: – the computation of jump addresses – data processing in tables – use of high-level languages such as C. l 64KB memory space with 16 16-bit registers that reduce fetches to memory. l Implements RISC architecture with 27 instructions and 7 addressing modes.
    [Show full text]
  • ECE 4750 Computer Architecture Topic 1: Microcoding
    ECE 4750 Computer Architecture Topic 1: Microcoding Christopher Batten School of Electrical and Computer Engineering Cornell University http://www.csl.cornell.edu/courses/ece4750 slide revision: 2013-09-01-10-42 Instruction Set Architecture Microcoded MIPS Processor Microcoding Discussion & Trends Agenda Instruction Set Architecture IBM 360 Instruction Set MIPS Instruction Set ISA to Microarchitecture Mapping Microcoded MIPS Processor Microcoded MIPS Microarchitecture #1 Microcoded MIPS Microarchitecture #2 Microcoding Discussion and Trends ECE 4750 T01: Microcoding 2 / 45 • Instruction Set Architecture • Microcoded MIPS Processor Microcoding Discussion & Trends Instruction Set Architecture I Contract between software & hardware Application Algorithm I Typically specified as all of the Programming Language programmer-visible state (registers & Operating System memory) plus the semantics of instructions Instruction Set Architecture Microarchitecture that operate on this state Register-Transfer Level IBM 360 was first line of machines to Gate Level I Circuits separate ISA from microarchitecture and Devices implementation Physics ... the structure of a computer that a machine language programmer must understand to write a correct (timing independent) program for that machine. — Amdahl, Blaauw, Brooks, 1964 ECE 4750 T01: Microcoding 3 / 45 • Instruction Set Architecture • Microcoded MIPS Processor Microcoding Discussion & Trends Compatibility Problem at IBM I By early 1960’s, IBM had several incompatible lines of computers! . Defense : 701 . Scientific : 704, 709, 7090, 7094 . Business : 702, 705, 7080 . Mid-Sized Business : 1400 . Decimal Architectures : 7070, 7072, 7074 I Each system had its own: . Instruction set . I/O system and secondary storage (tapes, drums, disks) . Assemblers, compilers, libraries, etc . Market niche ECE 4750 T01: Microcoding 4 / 45 • Instruction Set Architecture • Microcoded MIPS Processor Microcoding Discussion & Trends IBM 360: A General-Purpose Register Machine I Processor State .
    [Show full text]
  • The Implementation of Prolog Via VAX 8600 Microcode ABSTRACT
    The Implementation of Prolog via VAX 8600 Microcode Jeff Gee,Stephen W. Melvin, Yale N. Patt Computer Science Division University of California Berkeley, CA 94720 ABSTRACT VAX 8600 is a 32 bit computer designed with ECL macrocell arrays. Figure 1 shows a simplified block diagram of the 8600. We have implemented a high performance Prolog engine by The cycle time of the 8600 is 80 nanoseconds. directly executing in microcode the constructs of Warren’s Abstract Machine. The imulemention vehicle is the VAX 8600 computer. The VAX 8600 is a general purpose processor Vimal Address containing 8K words of writable control store. In our system, I each of the Warren Abstract Machine instructions is implemented as a VAX 8600 machine level instruction. Other Prolog built-ins are either implemented directly in microcode or executed by the general VAX instruction set. Initial results indicate that. our system is the fastest implementation of Prolog on a commercrally available general purpose processor. 1. Introduction Various models of execution have been investigated to attain the high performance execution of Prolog programs. Usually, Figure 1. Simplified Block Diagram of the VAX 8600 this involves compiling the Prolog program first into an intermediate form referred to as the Warren Abstract Machine (WAM) instruction set [l]. Execution of WAM instructions often follow one of two methods: they are executed directly by a The 8600 consists of six subprocessors: the EBOX. IBOX, special purpose processor, or they are software emulated via the FBOX. MBOX, Console. and UO adamer. Each of the seuarate machine language of a general purpose computer.
    [Show full text]