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144-545: Tiny BASIC was released as a specification, not an implementation, published in the September 1975 issue of the PCC newsletter. The article invited programmers to implement it on their machines and send the resulting assembler language implementation back for inclusion in a series of three planned newsletters. Li-Chen Wang , author of Palo Alto Tiny BASIC, coined the term " copyleft " to describe this concept. The community response

288-477: 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

432-540: A virtual machine , in which the Tiny BASIC interpreter is itself run on a virtual machine interpreter. The designer's idea to use an application virtual machine goes back to Val Schorre (with META II , 1964) and Glennie (Syntax Machine). The choice of a virtual machine approach economized on memory space and implementation effort, although the BASIC programs run thereon were executed somewhat slowly. Dialects that used

576-408: A 16-bit stack pointer to memory, replacing the 8008's internal stack , and a 16-bit program counter . The processor maintains internal flag bits (a status register ), which indicate the results of arithmetic and logical instructions. Only certain instructions affect the flags. The flags are: The carry bit can be set or complemented by specific instructions. Conditional-branch instructions test

720-552: A BASIC of its own, which would, hopefully, be the first for the MOS Technology 6502 processor. As the language needed 4 KB RAM, he made that the minimum memory for the design. Integer BASIC was originally published on Compact Cassette in 1976. Assembler 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 ,

864-525: A computed pointer can be executed with PCHL . LHLD loads HL from directly addressed memory and SHLD stores HL likewise. The XCHG instruction exchanges the values of the HL and DE register pairs. XTHL exchanges last item pushed on stack with HL. then if A 4-7 > 9 OR Cy = 1 then A ← A + 0x60 The 8080 supports up to 256 input/output (I/O) ports, accessed via dedicated I/O instructions taking port addresses as operands. This I/O mapping scheme

1008-453: A corresponding interrupt service routine , but are also often employed as fast system calls . The instruction that executes slowest is XTHL , which is used for exchanging the register pair HL with the value stored at the address indicated by the stack pointer. All 8-bit operations with two operands can only be performed on the 8-bit accumulator (the A register). The other operand can be either an immediate value, another 8-bit register, or

1152-566: A free software project before the free software movement . Computer hobbyists would exchange paper tapes, cassettes or even retype the files from the printed listings. Jim Warren, editor of Dr. Dobb's , wrote in the July 1976 ACM Programming Language newsletter about the motivations and methods of this successful project. He started with this: "There is a viable alternative to the problems raised by Bill Gates in his irate letter to computer hobbyists concerning 'ripping off' software. When software

1296-516: 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

1440-494: 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

1584-411: A larger number of customers. Much of the development effort was spent trying to integrate the functionalities of the 8008's supplemental chips into one package. It was decided early in development that the 8080 was not to be binary-compatible with the 8008, instead opting for source compatibility once run through a transpiler, to allow new software to not be subject to the same restrictions as the 8008. For

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1728-620: A line number, providing an assigned GOTO rather than the switch statement of the GOTO/GOSUB ... OF ... , a structure then supported in HP Time-Shared BASIC and predating ON ... GOTO . The syntax allowing IF-THEN statement (as opposed to just a line number to branch to) was not yet supported in Dartmouth BASIC at this time but had been introduced by Digital and copied by Microsoft. The Design Note specified

1872-478: 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

2016-717: 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

2160-481: 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

2304-479: A memory address, or a port number. Like more advanced processors, it has automatic CALL and RET instructions for multi-level procedure calls and returns (which can even be conditionally executed, like jumps) and instructions to save and restore any 16-bit register pair on the machine stack. Eight one-byte call instructions ( RST ) for subroutines exist at the fixed addresses 00h, 08h, 10h, ..., 38h. These are intended to be supplied by external hardware in order to invoke

2448-456: A memory byte addressed by the 16-bit register pair HL. Increments and decrements can be performed on any 8 bit register or an HL-addressed memory byte. Direct copying is supported between any two 8-bit registers and between any 8-bit register and an HL-addressed memory byte. Due to the regular encoding of the MOV instruction (using a quarter of available opcode space), there are redundant codes to copy

2592-438: 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

2736-410: 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

2880-522: 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

3024-400: 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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3168-415: A random number, $ before an expression loads a string at that address; OS returns to operating system. Memory was addressable as if it were a two-dimensioned array of high and low bytes (e.g., "(0,0)" to "(255,255)"); CALL executes a machine language subroutine. Many dialects appeared in various other publications. Inspired by PCC's call for Tiny BASICs, Robert Uiterwyk wrote MICRO BASIC 1.3 for

3312-706: A register into itself ( MOV B,B , for instance), which are of little use, except for delays. However, the systematic opcode for MOV M,M is instead used to encode the halt ( HLT ) instruction, halting execution until an external reset or interrupt occurs. Although the 8080 is generally an 8-bit processor, it has limited abilities to perform 16-bit operations. Any of the three 16-bit register pairs (BC, DE, or HL, referred to as B, D, H in Intel documents) or SP can be loaded with an immediate 16-bit value (using LXI ), incremented or decremented (using INX and DCX ), or added to HL (using DAD ). By adding HL to itself, it

3456-400: 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

3600-540: A small portion of the total code had to be ported. Allison's initial design was published in the September 1975 edition of the PCC newsletter, along with an Intel 8080 version of the IL interpreter. The article called on programmers to implement the design on their computer and send the resulting assembly language version back to the PCC. They stated their plans to publish three special newsletters containing these user-submitted versions, along with bug fixes, programs written in

3744-654: A trailing period. For instance, PRINT could be typed P. , although PR. and other variations also worked. This system was retained in Level I BASIC for the TRS-80 , which used PATB, and was also later found in Atari BASIC and the BASIC of various Sharp Pocket Computers . The most prominent dialects of Tiny BASIC were the original Design Note, Tiny BASIC Extended, Palo Alto Tiny BASIC, and 6800 Tiny BASIC. However, many other versions of Tiny BASIC existed. Tiny BASIC

3888-501: A wider variety of support chips were available; its instruction set was enhanced over the 8008; and its full 16-bit address bus (versus the 14-bit one of the 8008) enabled it to access 64 KB of memory, four times more than the 8008's range of 16 KB. It was used in the Altair 8800 and subsequent S-100 bus personal computers until it was replaced by the Z80 in this role, and was

4032-403: 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

4176-447: 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)

4320-453: 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

4464-843: Is also supported by NEC's V30 (a similarly enhanced 8086 clone). Thus, the 8080, via its instruction set architecture (ISA), made a lasting impact on computer history. A number of processors compatible with the Intel 8080A were manufactured in the Eastern Bloc : the KR580VM80A (initially marked as КР580ИК80) in the Soviet Union , the MCY7880 made by Unitra CEMI in Poland , the MHB8080A made by TESLA in Czechoslovakia ,

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4608-404: 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;

4752-442: 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

4896-508: 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

5040-469: Is for a subroutine named memcpy that copies a block of data bytes of a given size from one location to another. The data block is copied one byte at a time, and the data movement and looping logic utilizes 16-bit operations. The address bus has its own 16 pins, and the data bus has 8 pins that are usable without any multiplexing. Using the two additional pins (read and write signals), it is possible to assemble simple microprocessor devices very easily. Only

5184-536: Is free, or so inexpensive that it's easier to pay for it than to duplicate it, then it won't be 'stolen'." The Bill Gates letter was written to make software into products . The alternative method was to have an experienced professional do the overall design and then outline an implementation strategy. Knowledgeable amateurs would implement the design for a variety of computer systems. Warren predicted this strategy would be continued and expanded. The May 1976 issue of Dr. Dobbs has Li-Chen Wang 's Palo Alto Tiny BASIC for

5328-401: 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.,

5472-464: Is indeed addressed as if they were memory cells, "memory-mapped", leaving the I/O commands unused. I/O addressing can also sometimes employ the fact that the processor outputs the same 8-bit port address to both the lower and the higher address byte (i.e., IN 05h would put the address 0505h on the 16-bit address bus). Similar I/O-port schemes are used in the backward-compatible Zilog Z80 and Intel 8085, and

5616-679: 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

5760-442: 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

5904-407: 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

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6048-519: Is possible to achieve the same result as a 16-bit arithmetical left shift with one instruction. The only 16-bit instructions that affect any flag is DAD , which sets the CY (carry) flag in order to allow for programmed 24-bit or 32-bit arithmetic (or larger), needed to implement floating-point arithmetic . BC, DE, HL, or PSW can be copied to and from the stack using PUSH and POP . A stack frame can be allocated using DAD SP and SPHL . A branch to

6192-499: Is reflected in the paucity of features as well as details of its interpreter system . Early microcomputers lacked the RAM and secondary storage for a BASIC compiler , which was more typical of timesharing systems. Like most BASICs of the era, Tiny Basic was interactive with the user typing statements into a command line. As microcomputers of the era were often used with teletype machines or "dumb" terminals, direct editing of existing text

6336-474: Is regarded as an advantage, as it frees up the processor's limited address space. Many CPU architectures instead use so-called memory-mapped I/O (MMIO), in which a common address space is used for both RAM and peripheral chips. This removes the need for dedicated I/O instructions, although a drawback in such designs may be that special hardware must be used to insert wait states, as peripherals are often slower than memory. However, in some simple 8080 computers, I/O

6480-499: Is the primary 8-bit accumulator. The other six registers can be used as either individual 8-bit registers or in three 16-bit register pairs (BC, DE, and HL, referred to as B, D and H in Intel documents) depending on the particular instruction. Some instructions also enable the HL register pair to be used as a (limited) 16-bit accumulator. A pseudo-register M, which refers to the dereferenced memory location pointed to by HL, can be used almost anywhere other registers can be used. The 8080 has

6624-456: Is the second 8-bit microprocessor designed and manufactured by Intel . It first appeared in April 1974 and is an extended and enhanced variant of the earlier 8008 design, although without binary compatibility . Although earlier microprocessors were commonly used in mass-produced devices such as calculators , cash registers , computer terminals , industrial robots , and other applications,

6768-443: Is the successor to the 8008 . It uses the same basic instruction set and register model as the 8008, although it is neither source code compatible nor binary code compatible with its predecessor. Every instruction in the 8008 has an equivalent instruction in the 8080. The 8080 also adds 16-bit operations in its instruction set. Whereas the 8008 required the use of the HL register pair to indirectly access its 14-bit memory space,

6912-472: 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

7056-473: Is using a stolen copy of MITS BASIC should identify himself for what he is, a thief." Bill Gates made this more formal, writing " An Open Letter to Hobbyists ", complaining that "As the majority of hobbyists must be aware, most of you steal your software." The complaint was not well received. Among the many responses, Bob Albrecht, another Homebrew member and founder of the People's Computer Company (PCC), felt

7200-476: 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

7344-535: The Arduino . The earliest microcomputers , like the MITS Altair 8800 , generally had no built-in input/output (I/O) beyond front-panel switches and LED lamps. Useful work generally required the addition of an I/O expansion card and the use of some form of terminal . At the time, video-based terminals were very expensive, costing much more than the computer, so many users turned to mechanical devices like

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7488-471: 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

7632-657: The SWTPC 6800 system), which SWTPC published in the June 1976 issue of the SWTPC newsletter. Uiterwyk had handwritten the language on a legal tablet. He later expanded the language to 4K, adding support for floating point; this implementation was unique among BASIC interpreters by using Binary Coded Decimal to 9 digits of precision, with a range up to 10, and by being published for free as a "Floppy ROM" magazine insert. An 8K version added string variables and trigonometry functions. Both

7776-578: The Sharp PC-1211 pocket computer (1980), and Astro BASIC (1982, by Jamie Fenton ). Written by a junior in high school, MINOL was the only implementation that didn't support the full Design Note, lacking operator precedence , having only three relops (<, =, #), omitting GOSUB and RETURN . It only supported unsigned 8-bit precision (in contrast to signed 16-bit precision for every other implementation) and line numbers from 0 to 254. No spaces were permitted except in strings; ! returns

7920-535: The Teletype Model 33 . The Model 33, like most teleprinters of the era, included a tape punch system intended to allow operators to pre-record their messages and then play them at "high speed", faster than most individuals could type the message live. For the early microcomputers, this provided a convenient computer data storage format, allowing the users to write programs to paper tape and distribute them to other users. The Homebrew Computer Club met for

8064-506: The x86 and DOS for the PC a decade later). In 1979, even after the introduction of the Z80 and 8085 processors, five manufacturers of the 8080 were selling an estimated 500,000 units per month at a price around $ 3 to $ 4 each. The first single-board microcomputers , such as MYCRO-1 and the dyna-micro / MMD-1 (see: Single-board computer ) were based on the Intel 8080. One of the early uses of

8208-523: The +12 V pin being connected to +5 V and the −5 V pin to ground. The pin-out table, from the chip's accompanying documentation, describes the pins as follows: A key factor in the success of the 8080 was the broad range of support chips available, providing serial communications, counter/timing, input/output, direct memory access, and programmable interrupt control amongst other functions: The 8080 integrated circuit uses non-saturated enhancement-load nMOS gates, demanding extra voltages (for

8352-756: 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

8496-446: The 32 commands of the virtual machine in which the first Tiny BASIC interpreter was written. Tom Pittman , discussing the IL, says: "The TINY BASIC interpreter was designed by Dennis Allison as a recursive descent parser . Some of the elegant simplicity of this design was lost in the addition of syntactical sugar to the language but the basic form remains. The IL is especially suited to Recursive Descent parsing of TINY BASIC because of

8640-639: The 4K and 8K versions were sold by SWTPC. In January, 1978, Uiterwyk sold the rights of the source code to Motorola . Thomas F. Waitman wrote a Tiny BASIC in 1976 for the Hewlett-Packard HP-2640 and HP-2645 terminals (which used the Intel 8008 and 8080 processors), which was published in the Hewlett-Packard Journal . Published in the December 1976 issue of Interface Age was LLL ( Lawrence Livermore Laboratory ) BASIC,

8784-493: The 8080 added addressing modes to allow direct access to its full 16-bit memory space. The internal 7-level push-down call stack of the 8008 was replaced by a dedicated 16-bit stack-pointer (SP) register. The 8080's 40-pin DIP packaging permits it to provide a 16-bit address bus and an 8-bit data bus , enabling access to 64  KiB (2 bytes) of memory. The processor has seven 8-bit registers (A, B, C, D, E, H, and L), where A

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8928-462: The 8080 microprocessor. The first commercially-available arcade video game to incorporate a microprocessor was Gun Fight , Midway Games ' 8080-based reimplementation of Taito 's discrete-logic Western Gun , which was released in November 1975. (A pinball machine which incorporated a Motorola 6800 processor, The Spirit of '76 , had already been released the previous month. ) The 8080

9072-531: The 8080 saw greater success in a wider set of applications, and is largely credited with starting the microcomputer industry. Several factors contributed to its popularity: its 40-pin package made it easier to interface than the 18-pin 8008, and also made its data bus more efficient; its NMOS implementation gave it faster transistors than those of the P-type metal–oxide–semiconductor logic (PMOS) 8008, while also simplifying interfacing by making it TTL-compatible ;

9216-647: The 8080 was made in the late 1970s by Cubic-Western Data of San Diego, California, in its Automated Fare Collection Systems custom designed for mass transit systems around the world. An early industrial use of the 8080 is as the "brain" of the DatagraphiX Auto-COM (Computer Output Microfiche) line of products which takes large amounts of user data from reel-to-reel tape and images it onto microfiche. The Auto-COM instruments also include an entire automated film cutting, processing, washing, and drying sub-system. Several early video arcade games were built around

9360-486: The 8080. The listing begins with the title, author's name, and date but it also has "@ COPYLEFT ALL WRONGS RESERVED". A fellow Homebrew Computer Club member, Roger Rauskolb, modified and improved Wang's program and this was published in the December 1976 issue of Interface Age magazine. Roger added his name and preserved the COPYLEFT Notice. Tiny BASIC was designed to use as little memory as possible, and this

9504-603: The 8080APC made by Tungsram / MEV in Hungary , and the MMN8080 made by Microelectronica Bucharest in Romania . As of 2017 , the 8080 is still in production at Lansdale Semiconductors. The 8080 also changed how computers were created. When the 8080 was introduced, computer systems were usually created by computer manufacturers such as Digital Equipment Corporation , Hewlett-Packard , or IBM . A manufacturer would produce

9648-537: The IL program. This is a representative excerpt from the 120-line IL program: A common pattern in the program is to test for a keyword or part of a keyword, then act on that information. Each test is an assertion as to what is next in the line buffer. If the assertion fails, control jumps to a subsequent label (usually looking for a new keyword or token). Here the system advances its buffer cursor over any spaces and tests for GO and if it fails to find it then jumps to line S3 . If it finds it, execution continues with

9792-544: 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

9936-469: The ON-GOTO of larger BASIC implementations. The subroutine EXPR pushes the result of the expression onto the arithmetic stack (in this case, the line number). DONE verifies no other text follows the expression and gives an error if it does. XFER pops the number from the stack and transfers execution (GOes TO) the corresponding line number, if it exists. The following table gives a partial list of

10080-527: 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

10224-414: 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

10368-491: The Z80. At Intel, the 8080 was followed by the compatible and electrically more elegant 8085 . Later, Intel issued the assembly-language compatible (but not binary-compatible) 16-bit 8086 and then the 8/16-bit 8088 , which was selected by IBM for its new PC to be launched in 1981. Later NEC made the NEC V20 (an 8088 clone with Intel 80186 instruction set compatibility) which also supports an 8080 emulation mode. This

10512-402: 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

10656-503: The amount of memory required, there were only three messages and they consisted of single words. The system would respond with WHAT? for syntax errors, HOW? for run-time errors like GOTOs to a line that didn't exist or numeric overflows, and SORRY for out-of-memory problems. Wang also wrote a STARTREK program in his Tiny BASIC that appeared in the July 1976 issue of the People's Computer Company Newsletter . He later adapted

10800-424: 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

10944-496: The assembler during assembly. Since macros can have 'short' names but expand to several or indeed many lines of code, they can be used to make assembly language programs appear to be far shorter, requiring fewer lines of source code, as with higher level languages. They can also be used to add higher levels of structure to assembly programs, optionally introduce embedded debugging code via parameters and other similar features. Intel 8080 The Intel 8080 ( "eighty-eighty" )

11088-443: 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

11232-484: The best response would be to produce their own BASIC that was completely free to use by anyone. He approached Dennis Allison , a member of the Computer Science faculty at Stanford University , to write a specification for a version of BASIC that would fit in 2 to 3 kilobytes of memory. To aid porting , the design was based on an intermediate language (IL), an interpreter for the interpreter, which meant only

11376-586: 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

11520-674: 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

11664-460: The closely related x86 microprocessor families. One of the bits in the processor state word (see below) indicates that the processor is accessing data from the stack. Using this signal, it is possible to implement a separate stack memory space. This feature is seldom used. For more advanced systems, during the beginning of each machine cycle, the processor places an eight bit status word on the data bus. This byte contains flags that determine whether

11808-453: 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

11952-700: The difficulty outweighs the advantages." Defining Tiny BASIC for the Homebrew Computer Club, Pittman wrote, "Tiny BASIC is a proper subset of Dartmouth BASIC, consisting of the following statement types only: LET, PRINT, INPUT, IF, GOTO, GOSUB, RETURN, END, CLEAR, LIST, RUN. Arithmetic is in 16-bit integers only with the operators + - * / and nested parentheses. There are only the 26 single letter variable names A, B, ...Z, and no functions. There are no strings or arrays... Tiny BASIC specifies line numbers less than 256." He then went on to describe his implementation: "This language has been augmented to include

12096-570: The empty string. As is common in computer language grammar notation, the vertical bar (" | ") distinguishes alternatives, as does their being listed on separate lines. The symbol " CR " denotes a carriage return (usually generated by a keyboard's "Enter" key). A BREAK from the console will interrupt execution of the program. Note that string wasn't defined in the Design Note. This syntax, as simple as it was, added one innovation: GOTO and GOSUB could take an expression rather than just

12240-425: 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

12384-468: The first draft of which was developed by Steve Leininger from Allison's specification before Leininger left National Semiconductor for Tandy Corporation . The final interpreter was developed by John Dickenson, Jerry Barber, and John Teeter at the University of Idaho on a contract with LLL. Taking 5K, it included a floating-point package, developed by David Mead, Hal Brand, and Frank Olken. The program

12528-480: 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

12672-522: The first time in March 1975, and its members soon used the meetings to swap software on punched tape. At the June meeting, a tape containing a pre-release version of Altair BASIC disappeared. The tape was given to Steve Dompier, who passed it on to Dan Sokol, who had access to a high-speed tape punch. At the next meeting, 50 copies of Altair BASIC on paper tape appeared in a cardboard box. When Ed Roberts , founder of MITS, learned of this, he stated "Anyone who

12816-467: 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

12960-708: The functions RND, USR, and PEEK and POKE, giving the user access to all his system components in the 6800 from the BASIC program." Many implementers brought their own experiences with HP Time-Shared BASIC or DEC BASIC-PLUS to their designs and relaxed the formal Tiny BASIC language specification. Of the seven prominent implementations published by 1977: As an alternative to tokenization, to save RAM, TBX, DTB, and MINOL truncated keywords: PR for PRINT , IN for INPUT , RET for RETURN . The full, traditional keywords were not accepted. In contrast, PATB allowed accepted traditional keywords but also allowed any keyword to be abbreviated to its minimal unique string, with

13104-467: The general recursive nature of its procedures and the simplicity of the TINY BASIC tokens. The IL language is effectively optimized for the interpretation of TINY. Experience has shown that the difficulty of adding new features to the language is all out of proportion with the nature of the features. Usually it is necessary to add additional machine language subroutines to support the new features. Often

13248-543: The i8228 bus controller. The 8080 is implemented in N-type metal–oxide–semiconductor logic (NMOS) using non-saturated enhancement mode transistors as loads thus demanding a +12  V and a −5 V voltage in addition to the main transistor–transistor logic (TTL) compatible +5 V. Microprocessor customers were reluctant to adopt the 8008 because of limitations such as the single addressing mode, low clock speed, low pin count, and small on-chip stack, which restricted

13392-459: 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

13536-526: 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

13680-467: The language into 3K Control Basic for Cromemco , adding variable names of the form letter-digit (e.g., A0 to Z9 ), logic functions ( AND() , OR() , XOR() ), a CALL command to execute machine language routines, more PRINT -formatting options, and others ( GET() and PUT() instead of PEEK and POKE ; I/O port functions). Palo Alto Tiny BASIC was adapted for many other implementations, including Level I BASIC (1977), BASIC for

13824-462: The language were published, and similar articles began appearing in other magazines like Interface Age . By the middle of 1976, Tiny BASIC interpreters were available for the Intel 8080 , the Motorola 6800 and MOS Technology 6502 processors. This was a forerunner of the free software community's collaborative development before the internet allowed easy transfer of files, and was an example of

13968-511: The layout in August 1973. After the development of NMOS logic fabrication, a prototype of the 8080 was completed in January 1974. It had a flaw, in that driving with standard TTL devices increased the ground voltage because high current flowed into the narrow line. Intel had already produced 40,000 units of the 8080 at the direction of the sales section before Shima characterized the prototype. It

14112-403: 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

14256-514: The line number back to decimal format, and then print out the rest of the text in the line. When a program was present in memory and the user types in the RUN command, the system enters "indirect mode". In this mode, a pointer is set to point to the first line of the program, for instance, 10 ( $ 0A hex ). The original text for that line is then retrieved from the store and run as if the user had just typed it in direct mode. The pointer then advances to

14400-407: The line was entered with a leading number, the number was converted from decimal format, like "50", and converted to a 8-bit value, in this case, $ 32 hexadecimal . This number was used as an index into an array -like storage area where the rest of the line was stored in exactly the format it was typed. When the user typed LIST into the command line the system would loop over the array, convert

14544-411: The load-gate bias). It was manufactured in a silicon gate process using a minimal feature size of 6 μm. A single layer of metal is used to interconnect the approximately 4,500 transistors in the design, but the higher resistance polysilicon layer, which required higher voltage for some interconnects, is implemented with transistor gates. The die size is approximately 20 mm . The 8080

14688-446: The memory or I/O port is accessed and whether it is necessary to handle an interrupt. The interrupt system state (enabled or disabled) is also output on a separate pin. For simple systems, where the interrupts are not used, it is possible to find cases where this pin is used as an additional single-bit output port (the popular Radio-86RK computer made in the Soviet Union , for instance). The following 8080/8085 assembler source code

14832-427: 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

14976-570: The most notable changes in PATB is the addition of the FOR...NEXT loop . In the original TB, loops could only be implemented using IF and GOTO . As in Microsoft BASIC , the upper and lower bounds of the loop were set on loop entry, and did not change during the loop, so if one of the bounds was based on a variable expression; changing the variable did not change the bound. The STEP modifier

15120-423: 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

15264-485: The new BASIC, and suggestions and enhancements. The concept gained further notice when it was republished in the January 1976 edition of the ACM Special Interest Group on Programming Languages. Submissions poured in. Among the notable early versions was Tiny BASIC Extended by Dick Whipple and John Arnold which ran in 3K of RAM, added FOR...NXT loops, and allowed a single numeric array. They avoided

15408-409: 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

15552-410: The next IL command. In this case, the system next tests for TO , skipping to line S2 if it fails (a test for SUB , to see if this is instead a GOSUB command). If it passes, control continues; in this case, calling an IL subroutine that starts at label EXPR , which parses an expression. In Tiny BASIC, GOTO X*10+100 (a computed GO TO) is as legal as GOTO 100 and is the alternative to

15696-467: The next line and the process continues. The grammar is listed below in Backus–Naur form , almost exactly as it was specified in the Design Note. In the listing, an asterisk (" * ") denotes zero or more of the object to its left – except for the first asterisk in the definition of " term ", which is the multiplication operator; parentheses group objects; and an epsilon (" ε ") signifies

15840-400: 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,

15984-405: 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

16128-578: The original article appeared in the June/July issue of Dr. Dobb's (Vol. 1, No 6). This article also included information on adding additional I/O devices, using code for the VDM video display by Processor Technology as an example. Wang was one of the first to use word copyleft . In Palo Alto Tiny BASIC's distribution notice, he had written "@COPYLEFT ALL WRONGS RESERVED". Tiny BASIC was not distributed under any formal form of copyleft distribution terms, but

16272-439: The original article on Tiny BASIC from PCC, included the complete listing of Extended TB, and included a number of small BASIC programs including tips-and-tricks from Allison. Response to the first issue was so impressive that the introduction to the second issue stated they had already decided to continue publishing the new newsletter under the simplified name Dr. Dobb's Journal . Over the next several issues, additional versions of

16416-413: The original target CPU for CP/M operating systems developed by Gary Kildall . The 8080 directly influenced the later x86 architecture . Intel designed the 8086 to have its assembly language be similar enough to the 8080, with most instructions mapping directly onto each other, that transpiled 8080 assembly code could be executed on the 8086. The initial specified clock rate or frequency limit

16560-416: The permission to develop it nine months later. Faggin hired Masatoshi Shima , who helped design the logic of the 4004 with him, from Japan in November 1972. Shima did the detailed design under Faggin's direction, using the design methodology for random logic with silicon gate that Faggin had created for the 4000 family and the 8008. The 8080 was explicitly designed to be a general-purpose microprocessor for

16704-499: 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

16848-489: 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

16992-415: 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

17136-478: The same reason, as well as to expand the capabilities of stack-based routines and interrupts, the stack was moved to external memory. Noting the specialized use of general-purpose registers by programmers in mainframe systems, Faggin with Shima and Stanley Mazor decided the 8080's registers would be specialized, with register pairs having a different set of uses. This also allowed the engineers to more effectively use transistors for other purposes. Shima finished

17280-432: The scale and complexity of software. There were several proposed designs for the 8080, ranging from simply adding stack instructions to the 8008 to a complete departure from all previous Intel architectures. The final design was a compromise between the proposals. Federico Faggin , the originator of the 8080 architecture in early 1972, proposed the chip to Intel's management and pushed for its implementation. He finally got

17424-428: The separate IO space, interrupts, and DMA need added chips to decode the processor pin signals. However, the pin load capacity is limited; even simple computers often require bus amplifiers. The processor needs three power sources (−5, +5, and +12 V) and two non-overlapping high-amplitude synchronizing signals. However, at least the late Soviet version КР580ВМ80А was able to work with a single +5 V power source,

17568-433: 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

17712-407: 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

17856-456: 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

18000-496: 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

18144-414: 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

18288-591: 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

18432-460: The use of the IL and wrote it directly in machine code, using octal . The first of the three planned newsletters, with the title "Dr. Dobb's Journal of Computer Calisthenics & Orthodontia, Running Light Without Overbyte", was published in January 1976. It starts with a note from Albrecht, under the penname "the dragon", suggesting that three editions would not be enough, and asked the readers if they would like to see it continue. It also reprinted

18576-449: The various flag status bits. The accumulator and the flags together are called the PSW, or program status word. PSW can be pushed to or popped from the stack. As with many other 8-bit processors, all instructions are encoded in one byte (including register numbers, but excluding immediate data), for simplicity. Some can be followed by one or two bytes of data, which can be an immediate operand,

18720-424: The virtual machine included Tiny BASIC Extended, Tom Pittman 's Tiny BASIC and NIBL. Other dialects such as Denver Tiny BASIC (DTB) and Palo Alto Tiny BASIC were direct interpreters. Some programmers, such as Fred Greeb with DTB, treated the IL (Interpretive Language) program as pseudocode for the algorithm to implement in assembly language; Denver Tiny BASIC did not use a virtual machine, but it did closely follow

18864-463: The whole computer, including processor, terminals, and system software such as compilers and operating system. The 8080 was designed for almost any application except a complete computer system. Hewlett-Packard developed the HP 2640 series of smart terminals around the 8080. The HP 2647 is a terminal which runs the programming language BASIC on the 8080. Microsoft 's founding product, Microsoft BASIC ,

19008-431: Was 2  MHz , with common instructions using 4, 5, 7, 10, or 11 clock cycles. As a result, the processor is able to execute several hundred thousand instructions per second . Two faster variants, the 8080A-1 and 8080A-2, became available later with clock frequency limits of 3.125 MHz and 2.63 MHz respectively. The 8080 needs two support chips to function in most applications: the i8224 clock generator/driver and

19152-483: Was Palo Alto Tiny BASIC, or PATB for short, by Li-Chen Wang . PATB first appeared in the May 1976 edition of Dr. Dobbs , written in a custom assembly language with non-standard mnemonics. This led to further ports that worked with conventional assemblers on the 8080. The first version of the interpreter occupied 1.77 kilobytes of memory and assumed the use of a Teletype Machine (TTY) for user input/output . An erratum to

19296-614: Was expensive and typical memory size was only 4 to 8 KB. While the minimal version of Microsoft's Altair BASIC would also run in 4 KB machines, it left only 790 bytes free for BASIC programs. More free space was a significant advantage of Tiny BASIC. To meet these strict size limits, Tiny BASIC dialects generally lacked a variety of features commonly found in other dialects, for instance, most versions lacked string variables , lacked floating-point math , and allowed only single-letter variable names. Tiny BASIC implementations are still used today, for programming microcontrollers such as

19440-424: Was first published in a newsletter offshoot of the People's Computer Company , a newsletter which became Dr. Dobb's Journal , a long-lived computing magazine. About ten versions were published in the magazine. TBX was also known as Texas Tiny BASIC. Both SCELBAL and 6800 Tiny BASIC were announced in the magazine but did not publish their source code. One of the most popular of the many versions of Tiny BASIC

19584-405: Was not possible and the editor instead used takeout characters, often the backslash, to indicate where the user backed up to edit existing text. If the user typed a statement into the command line the system examined it to see if it started with a number. If it did not, the line was immediately parsed and operated on, potentially generating output via PRINT . This was known as "direct mode". If

19728-561: Was optional, as in MS. Another significant change was the ability to place several statements on a single line. For reasons not explained, PATB used the semicolon ; to separate statements, rather than the already common colon : . Other changes include the addition of a single numeric array, with the variable name @ , STOP in addition to END , and the use of # for not-equals in comparisons, as opposed to <> . PATB used words for error messages instead of numbers. To reduce

19872-425: Was originally programmed for the 8080. The 8080 and 8085 gave rise to the 8086, which was designed as a source code compatible , albeit not binary compatible , extension of the 8080. This design, in turn, later spawned the x86 family of chips, which continue to be Intel's primary line of processors. Many of the 8080's core machine instructions and concepts survive in the widespread x86 platform. Examples include

20016-586: Was placed into the public domain by LLL, which developed the system under the auspices of the U.S. Energy Research and Development Administration. Altair BASIC , 4K BASIC, could run within a 4 KB RAM machine, leaving only about 790 bytes free for program code. The Tiny BASIC initiative started in response to the $ 150 charge for Altair 4K BASIC. In 1975, Steve Wozniak joined the newly formed Homebrew Computer Club , which had fellow members Li-Chen Wang (Palo Alto Tiny BASIC) and Tom Pittman (6800 Tiny BASIC). Wozniak concluded that his machine would have to have

20160-536: Was presented in a context where source code was being shared and modified. In fact, Wang had earlier contributed edits to Tiny BASIC Extended before writing his own interpreter. He encouraged others to adapt his source code and publish their adaptions, as with Roger Rauskolb's version of PATB published in Interface Age . He also published a third version in PCC's Reference Book of Personal and Home Computing . One of

20304-487: Was released as requiring Low-power Schottky TTL (LS TTL) devices. The 8080A fixed this flaw. Intel offered an instruction set simulator for the 8080 named INTERP/80 to run compiled PL/M programs. It was written in FORTRAN IV by Gary Kildall while he worked as a consultant for Intel. There is only one patent on the 8080 with the following names: Federico Faggin, Masatoshi Shima, Stanley Mazor. The Intel 8080

20448-403: Was so overwhelming that the newsletter was relaunched as Dr. Dobb's Journal , the first regular periodical to focus on microcomputer software. Dr. Dobb's lasted in print form for 34 years and then online until 2014, when its website became a static archive. The small size and free source code made these implementations invaluable in the early days of microcomputers in the mid-1970s, when RAM

20592-482: Was then used in later Midway arcade video games and in Taito's 1978 Space Invaders , one of the most successful and well-known of all arcade video games. Zilog introduced the Z80 , which has a compatible machine language instruction set and initially used the same assembly language as the 8080, but for legal reasons, Zilog developed a syntactically-different (but code compatible) alternative assembly language for

20736-554: Was used in many early microcomputers, such as the MITS Altair 8800 Computer, Processor Technology SOL-20 Terminal Computer and IMSAI 8080 Microcomputer, forming the basis for machines running the CP/M operating system (the later, almost fully compatible and more able, Zilog Z80 processor would capitalize on this, with Z80 and CP/M becoming the dominant CPU and OS combination of the period c.  1976 to 1983 much as did

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