BASIC (Beginners' All-purpose Symbolic Instruction Code)

BASIC (Beginners' All-purpose Symbolic Instruction Code) is a family of general-purpose, high-level programming languages whose design philosophy emphasizes ease of use. The original version was designed by John G. Kemeny and Thomas E. Kurtz and released at Dartmouth College in 1964.

In addition to the language itself, Kemeny and Kurtz developed the Dartmouth Time Sharing System (DTSS), which allowed multiple users to edit and run BASIC programs at the same time. This general model became very popular on minicomputer systems like the PDP-11 and Data General Nova in the late 1960s and early 1970s.

The emergence of early microcomputers in the mid-1970s led to the development of a number of BASIC dialects, including Microsoft BASIC in 1975. Due to the tiny main memory available on these machines, often 4 kB, a variety of Tiny BASIC dialects was also created.

BASIC fell from use during the later 1980s as newer machines with far greater capabilities came to market and other programming languages (such as Pascal and C) became tenable. In 1991, Microsoft released Visual Basic, combining a greatly updated version of BASIC with a visual forms builder. This reignited use of the language and "VB" remains a major programming language in the form of VB.NET.

The introduction of the first microcomputers in the mid-1970s was the start of explosive growth for BASIC. It had the advantage that it was fairly well known to the young designers and computer hobbyists who took an interest in microcomputers, many of whom had seen BASIC on minis or maingrams. Despite Dijkstra's famous judgement in 1975, "It is practically impossible to teach good programming to students that have had a prior exposure to BASIC: as potential programmers they are mentally mutilated beyond hope of regeneration", BASIC was one of the few languages that was both high-level enough to be usable by those without training and small enough to fit into the microcomputers of the day, making it the de facto standard programming language on early microcomputers.

The first microcomputer version of BASIC was co-written by Bill Gates, Paul Allen and Monte Davidoff for their newly-formed company, Micro-Soft. This was released by MITS in punch tape format for the Altair 8800 shortly after the machine itself.

Li-Chen Wang (born 1935) is an American computer engineer, best known for his Palo Alto Tiny BASIC for Intel 8080-based microcomputers.

Micro-Soft, by this time Microsoft, ported their interpreter for the MOS 6502, which quickly become one of the most popular microprocessors of the 8-bit era. When new microcomputers began to appear, notably the "1977 trinity" of the TRS-80, Commodore PET and Apple II, they either included a version of the MS code, or quickly introduced new models with it.

The Apple II and TRS-80 each had two versions of BASIC, a smaller introductory version introduced with the initial releases of the machines and an MS-based version introduced as interest in the platforms increased.

When IBM was designing the IBM PC they followed the paradigm of existing home computers in wanting to have a built-in BASIC. They sourced this from Microsoft – IBM Cassette BASIC – but Microsoft also produced several other versions of BASIC for MS-DOS/PC DOS including IBM Disk BASIC (BASIC D), IBM BASICA (BASIC A), GW-BASIC (a BASICA-compatible version that did not need IBM's ROM) and QBasic, all typically bundled with the machine. In addition they produced the Microsoft BASIC Compiler aimed at professional programmers.

Turbo Pascal-publisher Borland published Turbo Basic 1.0 in 1985 (successor versions are still being marketed by the original author under the name PowerBASIC).

These later variations introduced many extensions, such as improved string manipulation and graphics support, access to the file system and additional data types. More important were the facilities for structured programming, including additional control structures and proper subroutines supporting local variables.

An important driver for the development of Visual Basic was as the new macro language for Microsoft Excel, a spreadsheet program. To the surprise of many at Microsoft who still initially marketed it as a language for hobbyists, the language came into widespread use for small custom business applications shortly after the release of VB version 3.0, which is widely considered the first relatively stable version.

While many advanced programmers still scoffed at its use, VB met the needs of small businesses efficiently as by that time, computers running Windows 3.1 had become fast enough that many business-related processes could be completed "in the blink of an eye" even using a "slow" language, as long as large amounts of data were not involved. Many small business owners found they could create their own small, yet useful applications in a few evenings to meet their own specialized needs.

Microsoft also produced VBScript in 1996 and Visual Basic .NET in 2001. The latter has essentially the same power as C# and Java but with syntax that reflects the original Basic language.

GOTO, GOSUB, ON ... GOTO/GOSUB是Dijkstra批评的主要原因。

REM holds a programmer's comment or REMark; often used to give a title to the program and to help identify the purpose of a given section of code. 怪不得.bat文件里也用REM表示注释。

USR transfers program control to a machine language subroutine, usually entered as an alphanumeric string or in a list of DATA statements. 比内嵌汇编更狠，内嵌机器码。

ASM some compilers such as Freebasic, Purebasic, and Powerbasic also support inline assembly language.

Minimal versions of BASIC had only integer variables and one- or two-letter variable names, which minimized requirements of limited and expensive memory (RAM).

Some dialects of BASIC supported matrices and matrix operations, useful for the solution of sets of simultaneous linear algebraic equations.

六级/考研单词: instruct, ease, multiple, edit, data, dialect, seldom, update, explode, compute, despite, fame, punch, interpret, era, pet, paradigm, bundle, successor, author, manipulate, invariable, excel, blink, latter, comment, bat, assemble, expense, simultaneous, algebra