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Millicode
In computer architecture, millicode is a higher level of microcode used to implement the instruction set of a computer. Millicode runs on top of the microcoded instructions and uses those instructions to implement more complex instructions visible to the user of the system. Implementation of millicode requires a special processor mode called millimode that provides its own set of registers, and possibly its own special instructions invisible to the user. IBM invented both the concept and the term ''millicode'' for the System/390 9672-G4 processor in 1997. The following are cited as advantages of millicode: * More complex instructions can easily be constructed from several millicode instructions. * Construction of a compatible line of computer models with different performance is simplified. * Millicode instructions can bypass CPU cache to improve performance. * Instructions can update multiple storage locations without concern for being interrupted. * Millicode can execute ins ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Microcode
In processor design, microcode (μcode) is a technique that interposes a layer of computer organization between the central processing unit (CPU) hardware and the programmer-visible instruction set architecture of a computer. Microcode is a layer of hardware-level instructions that implement higher-level machine code instructions or internal finite-state machine sequencing in many digital processing elements. Microcode is used in general-purpose central processing units, although in current desktop CPUs, it is only a fallback path for cases that the faster hardwired control unit cannot handle. Microcode typically resides in special high-speed memory and translates machine instructions, state machine data, or other input into sequences of detailed circuit-level operations. It separates the machine instructions from the underlying electronics so that instructions can be designed and altered more freely. It also facilitates the building of complex multi-step instructions, while red ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Computer Architecture
In computer engineering, computer architecture is a description of the structure of a computer system made from component parts. It can sometimes be a high-level description that ignores details of the implementation. At a more detailed level, the description may include the instruction set architecture design, microarchitecture design, logic design, and implementation. History The first documented computer architecture was in the correspondence between Charles Babbage and Ada Lovelace, describing the analytical engine. When building the computer Z1 in 1936, Konrad Zuse described in two patent applications for his future projects that machine instructions could be stored in the same storage used for data, i.e., the stored-program concept. Two other early and important examples are: * John von Neumann's 1945 paper, First Draft of a Report on the EDVAC, which described an organization of logical elements; and *Alan Turing's more detailed ''Proposed Electronic Calculator'' ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Instruction Set
In computer science, an instruction set architecture (ISA), also called computer architecture, is an abstract model of a computer. A device that executes instructions described by that ISA, such as a central processing unit (CPU), is called an ''implementation''. In general, an ISA defines the supported instructions, data types, registers, the hardware support for managing main memory, fundamental features (such as the memory consistency, addressing modes, virtual memory), and the input/output model of a family of implementations of the ISA. An ISA specifies the behavior of machine code running on implementations of that ISA in a fashion that does not depend on the characteristics of that implementation, providing binary compatibility between implementations. This enables multiple implementations of an ISA that differ in characteristics such as performance, physical size, and monetary cost (among other things), but that are capable of running the same machine code, so that ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
IBM ESA/390
The IBM System/390 is a discontinued mainframe product family implementing the ESA/390, the fifth generation of the System/360 instruction set architecture. The first computers to use the ESA/390 were the Enterprise System/9000 (ES/9000) family, which were introduced in 1990. These were followed by the 9672, Multiprise, and Integrated Server families of System/390 in 1994–1999, using CMOS microprocessors. The ESA/390 succeeded the ESA/370 used in the Enhanced 3090 and 4381 "E" models, and the System/370 architecture last used in the IBM 9370 low-end mainframe. The ESA/390 was succeeded by the 64-bit z/Architecture in 2000. History On February 15, 1988, IBM announced Enterprise Systems Architecture/370 (ESA/370) for 3090 enhanced ("E") models and for 4381 model groups 91E and 92E. In additional to the primary and secondary addressing modes that System/370 Extended Architecture (S/370-XA) supports, ESA has an access register mode in which each use of general registe ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
CPU Cache
A CPU cache is a hardware cache used by the central processing unit (CPU) of a computer to reduce the average cost (time or energy) to access data from the main memory. A cache is a smaller, faster memory, located closer to a processor core, which stores copies of the data from frequently used main memory locations. Most CPUs have a hierarchy of multiple cache levels (L1, L2, often L3, and rarely even L4), with different instruction-specific and data-specific caches at level 1. The cache memory is typically implemented with static random-access memory (SRAM), in modern CPUs by far the largest part of them by chip area, but SRAM is not always used for all levels (of I- or D-cache), or even any level, sometimes some latter or all levels are implemented with eDRAM. Other types of caches exist (that are not counted towards the "cache size" of the most important caches mentioned above), such as the translation lookaside buffer (TLB) which is part of the memory management unit (MMU) w ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
ES/9370
The IBM 9370 systems are "baby mainframe" midrange computers, released 1986 at the very low end of, and compatible with System/370. The media of the day, referring to the VAX systems manufactured by Digital Equipment Corporation (DEC), carried IBM's alleged " VAX Killer" phrase, albeit often skeptically. History The IBM 9370 was created in the aftermath of the failed Fort Knox project, which attempted to consolidate all of IBM's midrange systems into a single IBM 801-based hardware platform. The announcement described the IBM 9370 as a " super-mini computer" for commercial and engineering/scientific use—compact, rack-mounted, designed for an office environment, not needing a data center to be used. At the time of announcement the systems were positioned between IBM's midrange systems (IBM System/36 and IBM System/38), and the IBM 4300 mainframe series in performance. The IBM 9370 was partially a replacement for the also-not-so-successful IBM 8100 distributed processing eng ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
System/370
The IBM System/370 (S/370) is a model range of IBM mainframe computers announced on June 30, 1970, as the successors to the System/360 family. The series mostly maintains backward compatibility with the S/360, allowing an easy migration path for customers; this, plus improved performance, were the dominant themes of the product announcement. In September 1990, the System/370 line was replaced with the System/390. Evolution The original System/370 line was announced on June 30, 1970, with first customer shipment of the Models 155 and 165 planned for February 1971 and April 1971 respectively. The 155 first shipped in January 1971. System/370 underwent several architectural improvements during its roughly 20-year lifetime. The following features mentioned in Principles of Operation are either optional on S/360 but standard on S/370, introduced with S/370 or added to S/370 after announcement. *Branch and Save *Channel Indirect Data Addressing *Channel-Set Switching *Clear I/O *Co ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Springer-Verlag
Springer Science+Business Media, commonly known as Springer, is a German multinational publishing company of books, e-books and peer-reviewed journals in science, humanities, technical and medical (STM) publishing. Originally founded in 1842 in Berlin, it expanded internationally in the 1960s, and through mergers in the 1990s and a sale to venture capitalists it fused with Wolters Kluwer and eventually became part of Springer Nature in 2015. Springer has major offices in Berlin, Heidelberg, Dordrecht, and New York City. History Julius Springer founded Springer-Verlag in Berlin in 1842 and his son Ferdinand Springer grew it from a small firm of 4 employees into Germany's then second largest academic publisher with 65 staff in 1872.Chronology ". Springer Science+Business Media. In 1964, Springer expanded its business internationally, o ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
PALcode
PALcode (Privileged Architecture Library code) is the name used by DEC in the Alpha instruction set architecture (ISA) for a set of functions in the System Reference Manual (SRM) or AlphaBIOS firmware, providing a hardware abstraction layer for system software, covering features such as cache management, translation lookaside buffer (TLB) miss handling, interrupt handling, and exception handling. It evolved from a feature of the DEC PRISM architecture named Epicode. PALcode is Alpha machine code, running in a special mode that also allows access to internal registers specific to the particular Alpha processor implementation. Thus, it is somewhere between the role of microcode and of a hardware emulator. PALcode is operating system-specific, so different versions of PALcode are required by OpenVMS, Tru64 UNIX, and Windows NT. Tru64 UNIX PALcode is also used by NetBSD, FreeBSD, OpenBSD and Linux Linux ( or ) is a family of open-source Unix-like operating systems b ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Central Processing Unit
A central processing unit (CPU), also called a central processor, main processor or just processor, is the electronic circuitry that executes instructions comprising a computer program. The CPU performs basic arithmetic, logic, controlling, and input/output (I/O) operations specified by the instructions in the program. This contrasts with external components such as main memory and I/O circuitry, and specialized processors such as graphics processing units (GPUs). The form, design, and implementation of CPUs have changed over time, but their fundamental operation remains almost unchanged. Principal components of a CPU include the arithmetic–logic unit (ALU) that performs arithmetic and logic operations, processor registers that supply operands to the ALU and store the results of ALU operations, and a control unit that orchestrates the fetching (from memory), decoding and execution (of instructions) by directing the coordinated operations of the ALU, registers and other co ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Instruction Processing
Instruction or instructions may refer to: Computing * Instruction, one operation of a processor within a computer architecture instruction set * Computer program, a collection of instructions Music * Instruction (band), a 2002 rock band from New York City, US * "Instruction" (song), a 2017 song by English DJ Jax Jones * ''Instructions'' (album), a 2001 album by Jermaine Dupri Other uses * Instruction, teaching or education performed by a teacher * Sebayt, a work of the ancient Egyptian didactic literature aiming to teach ethical behaviour * Instruction, the pre-trial phase of an investigation led by a judge in an inquisitorial system of justice * Instruction manual, an instructional book or booklet ** Instruction manual (gaming), a booklet that instructs the player on how to play the game See also * Instructor (other) * Command (other) Command may refer to: Computing * Command (computing), a statement in a computer language * COMMAND.COM, the default operati ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
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