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90-635: Econet software was later mostly superseded by the TCP/IP -based Acorn Universal Networking (AUN), though some suppliers were still offering bridging kits to interconnect old and new networks. AUN was in turn superseded by the Acorn Access+ software. Econet was specified in 1980, and first developed for the Acorn Atom and Acorn System 2 / 3 / 4 computers in 1981. Also in that year the BBC Micro

180-477: A register . The binary code for this instruction is 10110 followed by a 3-bit identifier for which register to use. The identifier for the AL register is 000, so the following machine code loads the AL register with the data 01100001. This binary computer code can be made more human-readable by expressing it in hexadecimal as follows. Here, B0 means "Move a copy of the following value into AL ", and 61

270-517: A Bluetooth communication standard FAST TCP , a TCP congestion avoidance algorithm TCP/IP , the Internet protocol suite Medicine [ edit ] TCP (antiseptic) Tenocyclidine , an anesthetic drug Toxin-coregulated pilus, a protein that allows Vibrio cholerae to adhere to enterocytes Transcutaneous pacing Chemistry [ edit ] 1,2,3-Trichloropropane , an industrial solvent Thermal conversion process ,

360-499: A Z80 processor with 32 KB of private RAM, this being the X25 module accessing the X.25 line. The gateway and X25 modules communicated via 16 KB of dual-ported shared RAM. The X25 module was designed by Symicron and ran the "proven" Symicron Telematics Software (STS). Econet users would send network service requests to the gateway that would be forwarded by the STS functionality of

450-655: A bundle. Acorn's Hermann Hauser and Chris Curry agreed to allow it to be also offered with Econet fitted, as they had previously done with the disc interface. As previously with the Disc Filing System , they stipulated that Barson would need to adapt the network filing system from the System ;2 without assistance from Acorn. Barson's engineers applied a few modifications to fix bugs on the early BBC Micro motherboards, which were adopted by Acorn in later releases. With both floppy disc and networking available,

540-575: A card game Two-candidate-preferred vote , in the Australian electoral system Tax Compliance and Planning in the Uniform Certified Public Accountant Examination (United States) Topics referred to by the same term [REDACTED] This disambiguation page lists articles associated with the title TCP . If an internal link led you here, you may wish to change the link to point directly to

630-564: A depolymerization process for producing crude oil from waste Tocopherols , a class of methylated phenols Tricalcium phosphate , an anticaking agent Trichlorophenol , any organochloride of phenol that contains three covalently bonded chlorine atoms Tricresyl phosphate , an organophosphate compound Organizations [ edit ] Taiwan Communist Party , a political party in Taiwan Text Creation Partnership , an archival digitization effort at

720-405: A disc interface and single or dual drives. Printer sharing was also possible. This was intended for small networks, typically in an educational setting, to solve a narrowly defined problem of sharing what were at the time expensive peripherals. An Econet upgrade originally cost significantly less than a disk drive. The only available access control mechanism was that files for each station (client) on

810-409: A four byte header consisting of: A single data transmission consisted of four frames, each with a header as above: Each device on a network segment is identified by a "station ID" number which serves a similar purpose to a MAC address . The address is not set at time of manufacture but is set manually and a network administrator must ensure addresses do not collide when new machines are installed. In

900-516: A higher-level language, for performance reasons or to interact directly with hardware in ways unsupported by the higher-level language. For instance, just under 2% of version 4.9 of the Linux kernel source code is written in assembly; more than 97% is written in C . Assembly language uses a mnemonic to represent, e.g., each low-level machine instruction or opcode , each directive , typically also each architectural register , flag , etc. Some of

990-494: A language is used to represent machine code instructions is found in Kathleen and Andrew Donald Booth 's 1947 work, Coding for A.R.C. . Assembly code is converted into executable machine code by a utility program referred to as an assembler . The term "assembler" is generally attributed to Wilkes , Wheeler and Gill in their 1951 book The Preparation of Programs for an Electronic Digital Computer , who, however, used

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1080-478: A list of data, arguments or parameters. Some instructions may be "implied", which means the data upon which the instruction operates is implicitly defined by the instruction itself—such an instruction does not take an operand. The resulting statement is translated by an assembler into machine language instructions that can be loaded into memory and executed. For example, the instruction below tells an x86 / IA-32 processor to move an immediate 8-bit value into

1170-403: A machine is present on the network and its hardware platform. The machine-type codes which can be returned by that command are a useful indication of the range of hardware that offered Econet as their primary networking function or as an option: The manual includes an assembly language program to report a machine type, software version and release numbers. An update to the list in volume 5A of

1260-717: A macro definition, e.g., MEXIT in HLASM , while others may be permitted within open code (outside macro definitions), e.g., AIF and COPY in HLASM. In assembly language, the term "macro" represents a more comprehensive concept than it does in some other contexts, such as the pre-processor in the C programming language , where its #define directive typically is used to create short single line macros. Assembler macro instructions, like macros in PL/I and some other languages, can be lengthy "programs" by themselves, executed by interpretation by

1350-481: A mask of 0. Extended mnemonics are often used to support specialized uses of instructions, often for purposes not obvious from the instruction name. For example, many CPU's do not have an explicit NOP instruction, but do have instructions that can be used for the purpose. In 8086 CPUs the instruction xchg ax , ax is used for nop , with nop being a pseudo-opcode to encode the instruction xchg ax , ax . Some disassemblers recognize this and will decode

1440-662: A means to "extend the life of existing Acorn computers, such as the A310", allowing "any Archimedes computer to act as a fileserver", the emphasis had evidently shifted away from the Filestore and towards the Level 4 product at the start of the 1990s. A base Filestore E01S unit had a price inclusive of VAT of £1148.85 in February 1989, whereas an Archimedes 310 with 1 MB of RAM cost only £958.00 and an Econet module £56.35, illustrating

1530-438: A mnemonic is a symbolic name for a single executable machine language instruction (an opcode ), and there is at least one opcode mnemonic defined for each machine language instruction. Each instruction typically consists of an operation or opcode plus zero or more operands . Most instructions refer to a single value or a pair of values. Operands can be immediate (value coded in the instruction itself), registers specified in

1620-410: A move between a byte-sized register and either another register or memory, and the second byte, E0h, is encoded (with three bit-fields) to specify that both operands are registers, the source is AH , and the destination is AL . In a case like this where the same mnemonic can represent more than one binary instruction, the assembler determines which instruction to generate by examining the operands. In

1710-502: A parallel printer interface, expansion bus, Econet clock and termination circuits, a real-time clock , and a quantity of battery-backed RAM. The battery-backed RAM was used to hold configuration and authentication details. Initially, hard disk expansion was offered in the form of the E20 module providing a 3.5" 20 MB Winchester disk drive (hard disk) for the E01 base unit; later expansions in

1800-522: A programmer, so that one program can be assembled in different ways, perhaps for different applications. Or, a pseudo-op can be used to manipulate presentation of a program to make it easier to read and maintain. Another common use of pseudo-ops is to reserve storage areas for run-time data and optionally initialize their contents to known values. Symbolic assemblers let programmers associate arbitrary names ( labels or symbols ) with memory locations and various constants. Usually, every constant and variable

1890-400: A pseudoinstruction that expands to the machine's "set if less than" and "branch if zero (on the result of the set instruction)". Most full-featured assemblers also provide a rich macro language (discussed below) which is used by vendors and programmers to generate more complex code and data sequences. Since the information about pseudoinstructions and macros defined in the assembler environment

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1980-400: A second pass would require storing the symbol table in memory (to handle forward references ), rewinding and rereading the program source on tape , or rereading a deck of cards or punched paper tape . Later computers with much larger memories (especially disc storage), had the space to perform all necessary processing without such re-reading. The advantage of the multi-pass assembler is that

2070-403: Is a one-to-one correspondence between many simple assembly statements and machine language instructions. However, in some cases, an assembler may provide pseudoinstructions (essentially macros) which expand into several machine language instructions to provide commonly needed functionality. For example, for a machine that lacks a "branch if greater or equal" instruction, an assembler may provide

2160-447: Is a hexadecimal representation of the value 01100001, which is 97 in decimal . Assembly language for the 8086 family provides the mnemonic MOV (an abbreviation of move ) for instructions such as this, so the machine code above can be written as follows in assembly language, complete with an explanatory comment if required, after the semicolon. This is much easier to read and to remember. In some assembly languages (including this one)

2250-453: Is a key feature of assemblers, saving tedious calculations and manual address updates after program modifications. Most assemblers also include macro facilities for performing textual substitution – e.g., to generate common short sequences of instructions as inline , instead of called subroutines . Some assemblers may also be able to perform some simple types of instruction set -specific optimizations . One concrete example of this may be

2340-404: Is always completely unable to recover source comments. Each computer architecture has its own machine language. Computers differ in the number and type of operations they support, in the different sizes and numbers of registers, and in the representations of data in storage. While most general-purpose computers are able to carry out essentially the same functionality, the ways they do so differ;

2430-442: Is any low-level programming language with a very strong correspondence between the instructions in the language and the architecture's machine code instructions . Assembly language usually has one statement per machine instruction (1:1), but constants, comments , assembler directives , symbolic labels of, e.g., memory locations , registers , and macros are generally also supported. The first assembly code in which

2520-508: Is essential in assembly language programs, as the meaning and purpose of a sequence of binary machine instructions can be difficult to determine. The "raw" (uncommented) assembly language generated by compilers or disassemblers is quite difficult to read when changes must be made. Many assemblers support predefined macros , and others support programmer-defined (and repeatedly re-definable) macros involving sequences of text lines in which variables and constants are embedded. The macro definition

2610-401: Is given a name so instructions can reference those locations by name, thus promoting self-documenting code . In executable code, the name of each subroutine is associated with its entry point, so any calls to a subroutine can use its name. Inside subroutines, GOTO destinations are given labels. Some assemblers support local symbols which are often lexically distinct from normal symbols (e.g.,

2700-679: Is more than one assembler for the same architecture, and sometimes an assembler is specific to an operating system or to particular operating systems. Most assembly languages do not provide specific syntax for operating system calls, and most assembly languages can be used universally with any operating system, as the language provides access to all the real capabilities of the processor , upon which all system call mechanisms ultimately rest. In contrast to assembly languages, most high-level programming languages are generally portable across multiple architectures but require interpreting or compiling , much more complicated tasks than assembling. In

2790-442: Is most commonly a mixture of assembler statements, e.g., directives, symbolic machine instructions, and templates for assembler statements. This sequence of text lines may include opcodes or directives. Once a macro has been defined its name may be used in place of a mnemonic. When the assembler processes such a statement, it replaces the statement with the text lines associated with that macro, then processes them as if they existed in

Econet - Misplaced Pages Continue

2880-452: Is not compatible. The Acorn A4 laptop used another implementation, in the form of a 5 pin mini-DIN . Each Econet interface was controlled by a Motorola MC68B54 Advanced Data Link Controller (ADLC) chip, which handled electrical transmission/reception, frame checksumming and collision detection . Econet used a connectionless transmission model, similar to UDP , with no checksumming or error correction at this layer. Each packet had

2970-407: Is not present in the object program, a disassembler cannot reconstruct the macro and pseudoinstruction invocations but can only disassemble the actual machine instructions that the assembler generated from those abstract assembly-language entities. Likewise, since comments in the assembly language source file are ignored by the assembler and have no effect on the object code it generates, a disassembler

3060-524: Is universally enforced by their syntax. For example, in the Intel x86 assembly language, a hexadecimal constant must start with a numeral digit, so that the hexadecimal number 'A' (equal to decimal ten) would be written as 0Ah or 0AH , not AH , specifically so that it cannot appear to be the name of register AH . (The same rule also prevents ambiguity with the names of registers BH , CH , and DH , as well as with any user-defined symbol that ends with

3150-476: The xchg ax , ax instruction as nop . Similarly, IBM assemblers for System/360 and System/370 use the extended mnemonics NOP and NOPR for BC and BCR with zero masks. For the SPARC architecture, these are known as synthetic instructions . Some assemblers also support simple built-in macro-instructions that generate two or more machine instructions. For instance, with some Z80 assemblers

3240-471: The CPU pipeline as efficiently as possible. Assemblers have been available since the 1950s, as the first step above machine language and before high-level programming languages such as Fortran , Algol , COBOL and Lisp . There have also been several classes of translators and semi-automatic code generators with properties similar to both assembly and high-level languages, with Speedcode as perhaps one of

3330-601: The "Supported systems" section above are an indication of the range of hardware that was available or planned. Additional services could be implemented, using the network API provided. Short utilities such as network chat programs were often published in magazines or distributed by sharing among users; these made use of the Econet protocols to work alongside the basic file and print services. Larger software packages (some of them commercial) were available that provided services such as Teletext and modem drivers . Acorn emphasised

3420-756: The 1950s and early 1960s. Some assemblers have free-form syntax, with fields separated by delimiters, e.g., punctuation, white space . Some assemblers are hybrid, with, e.g., labels, in a specific column and other fields separated by delimiters; this became more common than column-oriented syntax in the 1960s. An assembler program creates object code by translating combinations of mnemonics and syntax for operations and addressing modes into their numerical equivalents. This representation typically includes an operation code (" opcode ") as well as other control bits and data. The assembler also calculates constant expressions and resolves symbolic names for memory locations and other entities. The use of symbolic references

3510-479: The BBC Micro the station ID is set using jumper pins on the motherboard. Conventionally a file server would be assigned station ID 254 but there is no specific requirement for this to be the case. There was provision for broadcast transmissions , a single frame sent with its destination station and network numbers set to 255. There was also provision for promiscuous mode reception, termed wild receive in

3600-454: The BBC Micro to implement a file server, and optionally a printer server also. The original file server was very basic, essentially allowing limited access to a floppy disc over the network. The server software was further developed over many years, and Acorn and other manufacturers also produced dedicated Econet servers based on various technologies. So the servers available fell into roughly three categories: The machine type numbers listed in

3690-593: The BBC Micro was approved for use in schools by all state and territory education authorities in Australia and New Zealand, and quickly overtook the Apple II as the computer of choice in private schools. With no other supporting documentation available, the head of Barson's Acorn division, Rob Napier, published Networking with the BBC Microcomputer , the first reference documentation for Econet. Econet

Econet - Misplaced Pages Continue

3780-535: The Econet protocol and AUN was removed from the Linux kernel in 2012 from version 3.5, due to lack of use and privilege escalation vulnerabilities. Econet was supported by a large number of different computer and server systems, produced both by Acorn and by other companies. As well as Acorn's MOS and RISC OS these also used other operating systems such as CP/M , DR-DOS , Unix , Linux or Microsoft Windows . The Econet API includes an Econet_MachinePeek command, which can be used by software to determine if

3870-418: The Filestore in the late 1980s as a solution for small workgroups , offering a base unit with optional hard disk storage modules. The device was similar in concept to what is now termed Network Attached Storage , being a standalone unit dedicated to serving files over a network. The Filestore was a 65C102-based machine with 64 KB of RAM , 64 KB of ROM , Econet connectivity, two 3.5" floppy drives,

3960-544: The Intel 8080 family and the Intel 8086/8088. Because Intel claimed copyright on its assembly language mnemonics (on each page of their documentation published in the 1970s and early 1980s, at least), some companies that independently produced CPUs compatible with Intel instruction sets invented their own mnemonics. The Zilog Z80 CPU, an enhancement of the Intel 8080A , supports all the 8080A instructions plus many more; Zilog invented an entirely new assembly language, not only for

4050-461: The PRM lists the following additions to the table above: Econet is a five-wire bus network composed of one or more segments (up to 127), where each segment may be up to 500m long. One pair of wires is used for the clock signal to synchronise devices on the network, one pair for data, and one wire as a common ground . In many but not all implementations, a dedicated external board is required to supply

4140-649: The PRM, requested by listening for station and network numbers both being zero. Technical details of packets and frames, the Econet API, and worked examples in ARM assembler and BBC BASIC are given in the RISC ;OS Programmer's Reference Manual. At the time and in the markets for which Econet was developed, the main purpose of computer networking was to provide local area shared access to expensive hardware such as disc storage and printers. Acorn provided software for

4230-528: The Terminal ROM providing terminal emulation and file transfer functionality. The gateway hardware consisted of the core functionality of a BBC Micro, this being the network service module connected to the Econet, combined with a Z80 second processor connected via the Tube interface, this acting as the gateway module and having 16 KB ROM and 32 KB of private RAM, augmented by another board with

4320-571: The University of Michigan, US The Children's Place , a US retailer The Clergy Project , US nonprofit helping clergy leave the ministry Top Cow Productions , a US comics publisher Trading Corporation of Pakistan , a Pakistani government organization Terceiro Comando Puro , a Brazilian criminal organization T.C. Pharmaceutical Industries Co. Ltd., manufacturer of Krating Daeng Other uses [ edit ] Taba International Airport (IATA code), Egypt Three card poker ,

4410-527: The V20 and V30 actually wrote in NEC's assembly language rather than Intel's; since any two assembly languages for the same instruction set architecture are isomorphic (somewhat like English and Pig Latin ), there is no requirement to use a manufacturer's own published assembly language with that manufacturer's products. There is a large degree of diversity in the way the authors of assemblers categorize statements and in

4500-463: The Z80, NEC invented new mnemonics for all of the 8086 and 8088 instructions, to avoid accusations of infringement of Intel's copyright. (It is questionable whether such copyrights can be valid, and later CPU companies such as AMD and Cyrix republished Intel's x86/IA-32 instruction mnemonics exactly with neither permission nor legal penalty.) It is doubtful whether in practice many people who programmed

4590-402: The absence of errata makes the linking process (or the program load if the assembler directly produces executable code) faster. Example: in the following code snippet, a one-pass assembler would be able to determine the address of the backward reference BKWD when assembling statement S2 , but would not be able to determine the address of the forward reference FWD when assembling

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4680-424: The architecture, these elements may also be combined for specific instructions or addressing modes using offsets or other data as well as fixed addresses. Many assemblers offer additional mechanisms to facilitate program development, to control the assembly process, and to aid debugging . Some are column oriented, with specific fields in specific columns; this was very common for machines using punched cards in

4770-443: The assembler operates and "may affect the object code, the symbol table, the listing file, and the values of internal assembler parameters". Sometimes the term pseudo-opcode is reserved for directives that generate object code, such as those that generate data. The names of pseudo-ops often start with a dot to distinguish them from machine instructions. Pseudo-ops can make the assembly of the program dependent on parameters input by

4860-586: The better-known examples. There may be several assemblers with different syntax for a particular CPU or instruction set architecture . For instance, an instruction to add memory data to a register in a x86 -family processor might be add eax,[ebx] , in original Intel syntax , whereas this would be written addl (%ebx),%eax in the AT&;T syntax used by the GNU Assembler . Despite different appearances, different syntactic forms generally generate

4950-674: The branch statement S1 ; indeed, FWD may be undefined. A two-pass assembler would determine both addresses in pass 1, so they would be known when generating code in pass 2. More sophisticated high-level assemblers provide language abstractions such as: See Language design below for more details. A program written in assembly language consists of a series of mnemonic processor instructions and meta-statements (known variously as declarative operations, directives, pseudo-instructions, pseudo-operations and pseudo-ops), comments and data. Assembly language instructions usually consist of an opcode mnemonic followed by an operand , which might be

5040-521: The bus was undriven. The original connectors were five-pin circular 180° DIN types . On later 32-bit machines (notably the A3020 and A4000), the Econet connection was made via five of the pins on their 15-pin D-type Network port, which could also accept MAUs (Media Attachment Units) to allow other types of network to be connected via the same socket. This port looks similar to an AUI port, but

5130-637: The capability to act as bridges between Econet and Ethernet networks, offering routing facilities to any Unix machines attached to the Econet, this being enabled by the IP-over-Econet support in RISC iX. An Econet X.25 gateway product was offered by Acorn, providing access to X.25 networks for computers on an Econet, with the X25 Terminal ROM and the existing Acorn DNFS ROM needing to be fitted to computers to enable access to X.25 services, with

5220-507: The clock signal known as the "clock box", usually positioned in the middle of the network. Some Econet devices have an internal capability to generate the clock signal. Signalling used the RS-422 5-volt differential standard, with one bit transferred per clock cycle. Unshielded cable was used for short lengths, and shielded cable for longer networks. The cable was terminated at each end to prevent reflections and to guarantee high logic levels when

5310-453: The corresponding assembly languages reflect these differences. Multiple sets of mnemonics or assembly-language syntax may exist for a single instruction set, typically instantiated in different assembler programs. In these cases, the most popular one is usually that supplied by the CPU manufacturer and used in its documentation. Two examples of CPUs that have two different sets of mnemonics are

5400-456: The file server host machine to necessitate a 6502 second processor unit with 64K RAM. Hierarchical directories were possible with the number of files limited only by the amount of storage available, enhanced access controls, random access to data files, and authentication support. Level 3 introduced Winchester hard drive support. With the release of the Level 4 Fileserver software providing

5490-425: The first decades of computing, it was commonplace for both systems programming and application programming to take place entirely in assembly language. While still irreplaceable for some purposes, the majority of programming is now conducted in higher-level interpreted and compiled languages. In " No Silver Bullet ", Fred Brooks summarised the effects of the switch away from assembly language programming: "Surely

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5580-480: The first example, the operand 61h is a valid hexadecimal numeric constant and is not a valid register name, so only the B0 instruction can be applicable. In the second example, the operand AH is a valid register name and not a valid numeric constant (hexadecimal, decimal, octal, or binary), so only the 88 instruction can be applicable. Assembly languages are always designed so that this sort of lack of ambiguity

5670-467: The following examples show. In each case, the MOV mnemonic is translated directly into one of the opcodes 88-8C, 8E, A0-A3, B0-BF, C6 or C7 by an assembler, and the programmer normally does not have to know or remember which. Transforming assembly language into machine code is the job of an assembler, and the reverse can at least partially be achieved by a disassembler . Unlike high-level languages , there

5760-524: The form of the E40S and E60S provided 40 MB and 60 MB storage respectively for the E01S base unit. The "S" suffix reportedly signifies that the units are "stacking". Acorn also offered the Level 1, Level 2 and Level 3 Fileserver solutions running on sufficiently upgraded BBC Micro or BBC Master computers. The Level 1 product offered access to existing Acorn DFS discs via a BBC Model B with Econet,

5850-516: The 💕 [REDACTED] Look up TCP in Wiktionary, the free dictionary. TCP may refer to: Science and technology [ edit ] Transformer coupled plasma Tool Center Point, see Robot end effector Topologically close pack (TCP) phases, also known as Frank-Kasper phases Computing [ edit ] Transmission Control Protocol , a fundamental Internet standard Telephony control protocol ,

5940-484: The gateway to the X.25 network. Incoming X.25 calls would be forwarded by the STS functionality to the network service functionality and on to the Econet. Network service requests could employ X.25, Yellow Book Transport Service, and X.29 protocols. While Econet was essentially specific to the Acorn range of computers, it does share common concepts with modern network file systems and protocols: TCP From Misplaced Pages,

6030-459: The instruction ld hl,bc is recognized to generate ld l,c followed by ld h,b . These are sometimes known as pseudo-opcodes . Mnemonics are arbitrary symbols; in 1985 the IEEE published Standard 694 for a uniform set of mnemonics to be used by all assemblers. The standard has since been withdrawn. There are instructions used to define data elements to hold data and variables. They define

6120-526: The instruction or implied, or the addresses of data located elsewhere in storage. This is determined by the underlying processor architecture: the assembler merely reflects how this architecture works. Extended mnemonics are often used to specify a combination of an opcode with a specific operand, e.g., the System/360 assemblers use B as an extended mnemonic for BC with a mask of 15 and NOP ("NO OPeration" – do nothing for one step) for BC with

6210-533: The intended article. Retrieved from " https://en.wikipedia.org/w/index.php?title=TCP&oldid=1242326096 " Category : Disambiguation pages Hidden categories: Short description is different from Wikidata All article disambiguation pages All disambiguation pages Assembly language In computer programming , assembly language (alternatively assembler language or symbolic machine code ), often referred to simply as assembly and commonly abbreviated as ASM or asm ,

6300-403: The letter H and otherwise contains only characters that are hexadecimal digits, such as the word "BEACH".) Returning to the original example, while the x86 opcode 10110000 ( B0 ) copies an 8-bit value into the AL register, 10110001 ( B1 ) moves it into CL and 10110010 ( B2 ) does so into DL . Assembly language examples for these follow. The syntax of MOV can also be more complex as

6390-427: The mnemonics may be built-in and some user-defined. Many operations require one or more operands in order to form a complete instruction. Most assemblers permit named constants, registers, and labels for program and memory locations, and can calculate expressions for operands. Thus, programmers are freed from tedious repetitive calculations and assembler programs are much more readable than machine code. Depending on

6480-423: The most powerful stroke for software productivity, reliability, and simplicity has been the progressive use of high-level languages for programming. Most observers credit that development with at least a factor of five in productivity, and with concomitant gains in reliability, simplicity, and comprehensibility." Today, it is typical to use small amounts of assembly language code within larger systems implemented in

6570-412: The network could be isolated from each other but anyone with physical access to the relevant station could access the files. Typically each station would only be able to access a small number of files, with only 31 files being stored in total on a side of one floppy disk and split between all of the stations. Level 2 delivered significant enhancements over level 1 but elevated the system requirements for

6660-463: The new instructions but also for all of the 8080A instructions. For example, where Intel uses the mnemonics MOV , MVI , LDA , STA , LXI , LDAX , STAX , LHLD , and SHLD for various data transfer instructions, the Z80 assembly language uses the mnemonic LD for all of them. A similar case is the NEC V20 and V30 CPUs, enhanced copies of the Intel 8086 and 8088, respectively. Like Zilog with

6750-400: The nomenclature that they use. In particular, some describe anything other than a machine mnemonic or extended mnemonic as a pseudo-operation (pseudo-op). A typical assembly language consists of 3 types of instruction statements that are used to define program operations: Instructions (statements) in assembly language are generally very simple, unlike those in high-level languages . Generally,

6840-405: The operation, and if necessary, pad it with one or more " no-operation " instructions in a later pass or the errata. In an assembler with peephole optimization , addresses may be recalculated between passes to allow replacing pessimistic code with code tailored to the exact distance from the target. The original reason for the use of one-pass assemblers was memory size and speed of assembly – often

6930-513: The pricing considerations for potential buyers. By 1991, the Filestore was apparently no longer offered in Acorn's pricing (nor was the A310), but the Level 4 software was priced at £233.83 and an Archimedes 410/1 with 1 MB of RAM at £1049.33. With the introduction of Acorn's Unix workstations running RISC iX , an envisaged application for Econet was the use of Master 128 computers acting as terminals to these Unix systems. Such systems also offered

7020-499: The same mnemonic is used for different instructions, that means that the mnemonic corresponds to several different binary instruction codes, excluding data (e.g. the 61h in this example), depending on the operands that follow the mnemonic. For example, for the x86/IA-32 CPUs, the Intel assembly language syntax MOV AL, AH represents an instruction that moves the contents of register AH into register AL . The hexadecimal form of this instruction is: The first byte, 88h, identifies

7110-489: The same mnemonic, such as MOV, may be used for a family of related instructions for loading, copying and moving data, whether these are immediate values, values in registers, or memory locations pointed to by values in registers or by immediate (a.k.a. direct) addresses. Other assemblers may use separate opcode mnemonics such as L for "move memory to register", ST for "move register to memory", LR for "move register to register", MVI for "move immediate operand to memory", etc. If

7200-415: The same numeric machine code . A single assembler may also have different modes in order to support variations in syntactic forms as well as their exact semantic interpretations (such as FASM -syntax, TASM -syntax, ideal mode, etc., in the special case of x86 assembly programming). There are two types of assemblers based on how many passes through the source are needed (how many times the assembler reads

7290-433: The source code file (including, in some assemblers, expansion of any macros existing in the replacement text). Macros in this sense date to IBM autocoders of the 1950s. Macro assemblers typically have directives to, e.g., define macros, define variables, set variables to the result of an arithmetic, logical or string expression, iterate, conditionally generate code. Some of those directives may be restricted to use within

7380-407: The source) to produce the object file. In both cases, the assembler must be able to determine the size of each instruction on the initial passes in order to calculate the addresses of subsequent symbols. This means that if the size of an operation referring to an operand defined later depends on the type or distance of the operand, the assembler will make a pessimistic estimate when first encountering

7470-484: The technology, which it refused. With the falling prices and widespread adoption of IP networking in the early 1990s, Acorn Universal Networking (AUN), an implementation of Econet protocols and addressing over TCP/IP (in Acorn's words "an AUN network is a conformant TCP/IP network underneath the Econet-like veneer"), was developed to provide legacy support for Econet on Ethernet -connected machines. Support for

7560-456: The term to mean "a program that assembles another program consisting of several sections into a single program". The conversion process is referred to as assembly , as in assembling the source code . The computational step when an assembler is processing a program is called assembly time . Because assembly depends on the machine code instructions, each assembly language is specific to a particular computer architecture . Sometimes there

7650-496: The type of data, the length and the alignment of data. These instructions can also define whether the data is available to outside programs (programs assembled separately) or only to the program in which the data section is defined. Some assemblers classify these as pseudo-ops. Assembly directives, also called pseudo-opcodes, pseudo-operations or pseudo-ops, are commands given to an assembler "directing it to perform operations other than assembling instructions". Directives affect how

7740-414: The ubiquitous x86 assemblers from various vendors. Called jump-sizing , most of them are able to perform jump-instruction replacements (long jumps replaced by short or relative jumps) in any number of passes, on request. Others may even do simple rearrangement or insertion of instructions, such as some assemblers for RISC architectures that can help optimize a sensible instruction scheduling to exploit

7830-591: The use of "10$ " as a GOTO destination). Some assemblers, such as NASM , provide flexible symbol management, letting programmers manage different namespaces , automatically calculate offsets within data structures , and assign labels that refer to literal values or the result of simple computations performed by the assembler. Labels can also be used to initialize constants and variables with relocatable addresses. Assembly languages, like most other computer languages, allow comments to be added to program source code that will be ignored during assembly. Judicious commenting

7920-481: Was available. It used Microsoft 's MS-NET Redirector for MS-DOS to provide file and printer sharing via the NET ;USE command. File, Print and Tape servers, for the architecture were also supplied by third-party vendors such as S J Research. Econet was supported by Acorn MOS , RISC OS , RISC iX , FreeBSD and Linux operating systems. Acorn once received an offer from Commodore International to license

8010-673: Was officially released for the BBC Micro in the UK in 1984, and it later became popular as a networking system for the Acorn Archimedes . Econet was eventually officially supported on all post-Atom Acorn machines, apart from the Electron (except in Australia and New Zealand where Barson Computers built their own Econet daughterboard ), along with third-party ISA cards for the IBM PC. The "Ecolink" ISA interface card for IBM-compatible PCs

8100-520: Was released, initially with provision for floppy disc and Econet interface ports, but without the necessary supporting ICs fitted, optionally to be added in a post sale upgrade. In 1982, the Tasmania Department of Education requested a tender for the supply of personal computers to their schools. Earlier that year Barson Computers, Acorn's Australian computer distributor, had released the BBC Microcomputer with floppy disc storage as part of

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