BASIC

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Revision as of 08:41, 16 July 2011 (view source)

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Ada Lovelace's contributions as an early programmer are most evident in her translation of and notes to an Italian article about Charles Babbage's Analytical Engine by Louis Menebrea. In this work, completed in 1843, she envisioned the Analytical Engine as a general-purpose computer and described an algorithm that could be used to output Bernoulli numbers. Although the computer to execute Lovelace's program was never built, her project made an important contribution to the modern idea of the computer program (Fuegi & Francis). This contribution was the concept that a program consisted of an algorithm delineated in mathematical notation.

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The computer programs that followed in the electromechanical and early electronic age of computing were less intelligible than Lovelace's algorithm, bearing little relationship to any kind of written word -- or numbers. For example, the ENIAC, a fully electronic computer built at the University of Pennsylvania from 1943 to 1945, was programmed initially by plugging in an elaborate set of cables (da Cruz). To run particular calculations, constants were then set using dials.

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The computer programs that followed in the electro-mechanical and early electronic age of computing were less intelligible than Lovelace's algorithm, bearing little relationship to any kind of written word -- or numbers. For example, the ENIAC, a fully electronic computer built at the University of Pennsylvania from 1943 to 1945, was programmed initially by plugging in an elaborate set of cables (da Cruz). To run particular calculations, constants were then set using dials.

The next step in programming was machine language. A program in machine language was simply a sequence of numbers that spoke, as it were, to the machine in the machine's own language. Each number corresponded to a particular machine operation, while the operands, if there were any, were similarly provided as numbers. On the ENIAC, these numbers were decimal (base 10), but different bases were used on other early systems. The EDVAC used binary; the ORDVAC, octal; and the BRLESC, sexadecimal (Bergin 62). In all of these cases, programmers arduously determined the sequence of numbers that would constitute a program, resulting in code that did not remotely resemble any spoken human language. For instance, to jump unconditionally to a particular absolute address, an opcode such as "76" (in base 10) is used, followed by two bytes specifying the address. In fact, this is the opcode used for an unconditional branch to an absolute address on the Commodore 64 -- though one would never know from looking at it.

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 Ada Lovelace's contributions as an early programmer are most evident in her translation of and notes to an Italian article about Charles Babbage's Analytical Engine by Louis Menebrea. In this work, completed in 1843, she envisioned the Analytical Engine as a general-purpose computer and described an algorithm that could be used to output Bernoulli numbers. Although the computer to execute Lovelace's program was never built, her project made an important contribution to the modern idea of the computer program (Fuegi & Francis). This contribution was the concept that a program consisted of an algorithm delineated in mathematical notation.
-The computer programs that followed in the electromechanical and early electronic age of computing were less intelligible than Lovelace's algorithm, bearing little relationship to any kind of written word -- or numbers. For example, the ENIAC, a fully electronic computer built at the University of Pennsylvania from 1943 to 1945, was programmed initially by plugging in an elaborate set of cables (da Cruz). To run particular calculations, constants were then set using dials.
+The computer programs that followed in the electro-mechanical and early electronic age of computing were less intelligible than Lovelace's algorithm, bearing little relationship to any kind of written word -- or numbers. For example, the ENIAC, a fully electronic computer built at the University of Pennsylvania from 1943 to 1945, was programmed initially by plugging in an elaborate set of cables (da Cruz). To run particular calculations, constants were then set using dials.
 The next step in programming was machine language. A program in machine language was simply a sequence of numbers that spoke, as it were, to the machine in the machine's own language. Each number corresponded to a particular machine operation, while the operands, if there were any, were similarly provided as numbers. On the ENIAC, these numbers were decimal (base 10), but different bases were used on other early systems. The EDVAC used binary; the ORDVAC, octal; and the BRLESC, sexadecimal (Bergin 62). In all of these cases, programmers arduously determined the sequence of numbers that would constitute a program, resulting in code that did not remotely resemble any spoken human language. For instance, to jump unconditionally to a particular absolute address, an opcode such as "76" (in base 10) is used, followed by two bytes specifying the address. In fact, this is the opcode used for an unconditional branch to an absolute address on the Commodore 64 -- though one would never know from looking at it.