1、BRITISH STANDARD BS7238:1990 IEC824:1988 Glossary for Terminology related to microprocessorsBS7238:1990 This BritishStandard, having been prepared under the directionof the Information Systems Technology StandardsPolicy Committee, waspublished under the authorityof the Board of BSI andcomes into eff
2、ect on 31July1990 BSI 12-1999 The following BSI references relate to the work on this standard: Committee reference IST/6 Draft for comment89/65512DC ISBN 0 580 18119 7 Committees responsible for this BritishStandard The preparation of this BritishStandard was entrusted by the Information Systems Te
3、chnology Standards Policy Committee (IST/-) to Technical Committee IST/6, upon which the following bodies were represented: Association for Payment Clearing Services British Computer Society British Telecommunications plc Business Equipment and Information Technology Association Department of Trade
4、and Industry (Information Technology Division) Department of Trade and Industry (National Physical Laboratory) Electricity Supply Industry in England and Wales Electronic Engineering Association H.M. Treasury (Central Computer and Telecommunications Agency) Information Technology Users Standards Ass
5、ociation Inter-universities Computing Committee Joint Network Team LAMSAC National Computing Centre Ltd. National Health Services OFTEL (Office of Telecommunications) Post Office Telecommunication Engineering and Manufacturing Association Telecommunications Managers Association User Standards Forum
6、for Information Technology (Institute of Data Processing Management) Amendments issued since publication Amd. No. Date CommentsBS7238:1990 BSI 12-1999 i Contents Page Committees responsible Inside front cover National foreword ii Scope 1 1 Terms and definitions 1 Publications referred to Inside back
7、 coverBS7238:1990 ii BSI 12-1999 National foreword This BritishStandard, prepared under the direction of the Information Systems Technology Standards Policy Committee, is identical with IEC824:1988 “Terminology related to microprocessors” published by the International Electrotechnical Commission (I
8、EC). The Technical Committee has reviewed the provisions of ISO2382 to which reference is made in the text, and has decided that they are acceptable for use in conjunction with this standard. A British Standard does not purport to include all the necessary provisions of a contract. Users of British
9、Standards are responsible for their correct application. Compliance with a British Standard does not of itself confer immunity from legal obligations. Cross-reference International Standard Corresponding BritishStandard IEC748-2 (1985) BS6493 Semiconductor devices Section 2.2:1986 Recommendations fo
10、r digital integrated circuits (Identical) Summary of pages This document comprises a front cover, an inside front cover, pagesi andii, pages1 to4, an inside back cover and a back cover. This standard has been updated (see copyright date) and may have had amendments incorporated. This will be indicat
11、ed in the amendment table on the inside front cover.BS7238:1990 BSI 12-1999 1 Scope This standard gives terms and definitions applicable to microprocessor systems. 1 Terms and definitions NOTEWhere indicated, terms and definitions have been taken from the following parts and sections of ISO Standard
12、2382: section 07; section 10; part 11; part 12. 1.1 Architecture 1.1.1 bus a common path along which signals travel from one of several sources to one or several destinations 1.1.2 arithmetic logic arithmetic and logic unit, ALU (abbreviation) (ISO2382-1111.01.08) in a processor the part that perfor
13、ms arithmetic operations logic operations, arithmetic operations and logic operations NOTEThe term “arithmetic unit” is sometimes used for a unit that performs both arithmetic and logic operations. 1.1.3 (instruction) control unit (ISO2382-1111.01.02) in a processor, the part that retrieves instruct
14、ions in proper sequence, interprets each instruction, and applies the proper signals to the arithmetic and logic unit and other parts in accordance with this interpretation 1.1.4 program counter equivalent to ISO definition of “Instruction address register, program register, instruction pointer regi
15、ster” (ISO2382-1111.02.02) a special purpose register used to hold the address of the next instruction to be executed 1.1.5 register (ISO2382-1111.01.19) a part of internal storage having a specified storage capacity and usually intended for a specific purpose NOTESub-clause 1.3.11 of ChapterII of I
16、EC Publication 748-2 reads: “An arrangement of bistable circuits by means of which information may be accepted, stored, and retrieved. NOTEThe register may form part of another memory and is of a specified capacity.” 1.1.6 register length (ISO2382-1111.02.15) the storage capacity of a register 1.1.7
17、 general purpose register (ISO2382-1111.02.08) a register, usually explicitly addressable, within a set of registers, that can be used for different purposes, such as an accumulator, an index register, or a special handler of data 1.1.8 address register register that is used to hold an address 1.1.9
18、 base address (ISO2382-VII07.19.05) a numeric value that is used as a reference in the calculation of addresses in the execution of a computer program 1.1.10 base (address) register (ISO2382-1111.02.04) a register that holds a base address 1.1.11 read/write register register that is used to hold dat
19、a received from or to be transmitted to the bus 1.1.12 instruction register (ISO2382-1111.02.01) a register that is used to hold an instruction for interpretation 1.1.13 accumulator (ISO2382-1111.02.11) a register in which one operand of an operation can be stored and subsequently replaced by the re
20、sult of an operation 1.1.14 index register (ISO2382-1111.02.03) a register whose contents can be used to modify an operand address during the execution of computer instructions NOTEAn index register may be used as a counter to control the execution of a loop, to control the use of an array, for tabl
21、e look-up, as a switch, or as a pointer. 1.1.15 indicator (ISO2382-VII07.06.05) an item of data that may be interrogated to determine whether a particular condition has been satisfied in the execution of a computer program examples: A switch indicator; an overflow indicator 1.1.16 condition code reg
22、ister, indicator register a register containing the indicators that result from the operation of the arithmetic and logic unit NOTEThe register may also contain other indicators.BS7238:1990 2 BSI 12-1999 1.1.17 status (of a central processing unit) one or more data bits showing which one of a class
23、of operations is being performed, has been completed or is recognized by the central processing unit 1.1.18 status register a register containing one or more status bits 1.1.19 pushdown storage, stock (storage) (ISO/DIS2382-12.212.02.24) a storage device in which data are ordered in such a way that
24、the next data element to be retrieved is the most recently stored NOTEThe method is characterized by “last-in-first-out” (LIFO). 1.1.20 stack pointer, stack indicator (ISO/DIS2382-12.212.02.26) the address of the storage location holding the item of data most recently stored in a pushdown storage re
25、mark: This term is frequently used to refer to the stack pointer register 1.1.21 bit slice processor a central processing unit constructed of an array of identical units, each of which operates simultaneously upon one or more adjacent bits 1.2 Operation 1.2.1 hold (input) signal a signal that causes
26、 a central processing unit to stop its activity and to relinquish control over the bus until the signal is removed 1.2.2 ready signal signal from a device to indicate to another device: that it is ready to send or receive data, or that the data transfer has been completed. 1.2.3 wait signal a signal
27、 indicating that the device addressed by the central processing unit has not yet completed its data transfer 1.2.4 to reset (a counter) (ISO2382-1111.03.24) to cause a counter to take the state corresponding to a specified initial number 1.2.5 machine cycle the sequence of operations in a central pr
28、ocessing unit that corresponds to one memory cycle, input/output (I/O) cycle or equivalent internal operation NOTEAn instruction may require one or more machine cycles for its execution and a machine cycle usually contains more than one clock cycle. 1.2.6 clock cycle the time period, generally deriv
29、ed from an oscillator, that is used for sequencing data flow and synchronizing one or more functions 1.2.7 anticipatory fetching, pre-fetching a procedure in which stored instructions are read from memory by the central processing unit prior to the moment of need 1.2.8 cascaded carry (ISO2382-1111.0
30、3.16) in parallel addition, a procedure in which the addition results in a partial sum numeral and a carry numeral which are in turn added; this process is repeated until a zero carry is generated 1.2.9 high-speed carry (ISO2382-1111.03.14) in parallel addition, any procedure for speeding up the pro
31、cessing of carries example: Standing-on-nines carry 1.2.10 look-ahead carry a high-speed carry procedure in which a group of carry digits is formed in parallel from the respective input bits of the two groups that are to be added and, if it exists, from the most significant carry digit that is previ
32、ous to those groups 1.2.11 memory segment a block of memory that is identified by a base address and has been allocated for a specific purpose NOTEIn common usage different portions of memory may be designated as, for example, data segment, stack segment. 1.2.12 segment (ISO2382-VII07.12.05) a self-
33、contained portion of a computer program that may be executed without the entire computer program necessarily being maintained in the internal storage at any one time NOTEThe term “memory” is frequently used for “storage”.BS7238:1990 BSI 12-1999 3 1.2.13 interrupt, interruption (ISO2382-X10.01.09) a
34、suspension of a process, such as the execution of a computer program, caused by an event external to that process, and performed in such a way that the process can be resumed 1.2.14 interrupt vector an address held in a special purpose register or in memory that indicates the instruction to be execu
35、ted on acceptance of the associated interrupt NOTEThe term “interrupt vector” has also been used to describe an array of interrupt vectors that may be indexed. 1.2.15 bus arbitration a procedure that resolves priorities among units contending for control of a common bus and that passes control to th
36、e selected unit 1.2.16 coprocessor a processing unit that extends the capabilities of its main processor, directly accesses the memory of that processor, and does not operate autonomously 1.2.17 multiprocessor (ISO2382-1111.01.07) a computer including two or more central processors that have common
37、access to a main storage NOTEThe term “memory” is frequently used for “storage”. 1.3 Programming 1.3.1 microprogram (ISO2382-VII07.01.13) a sequence of elementary instructions that corresponds to a specific computer operation, that is maintained in special storage, and whose execution is initiated b
38、y the introduction of a computer instruction into an instruction register of a computer4 blankBS7238:1990 BSI 12-1999 Publications referred to Seenational foreword.BS7238:1990 IEC824:1988 BSI 389 Chiswick High Road London W4 4AL BSIBritishStandardsInstitution BSI is the independent national body res
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