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VisiCalc (for "visible calculator")〔(【引用サイトリンク】title=A sidebar to the article "Ten Years of Rows and Columns" published in Byte, issue 13/1989, pp. 326-328. )〕 was the first spreadsheet computer program for personal computers, originally released for the Apple II. It is often considered the application that turned the microcomputer from a hobby for computer enthusiasts into a serious business tool, and is considered the Apple II's killer app. VisiCalc sold over 700,000 copies in six years, and as many as 1 million copies over its history. Initially developed in a 6502 assembler running on the Multics time sharing system, VisiCalc was ported to numerous platforms, both 8-bit and some of the early 16-bit systems. In order to do this, the company developed porting platforms that produced bug compatible versions. The company took the same approach when the IBM PC was launched, producing a product that was essentially identical to the original 8-bit Apple II version. Sales were initially brisk, with about 300,000 copies sold. VisiCalc used the A1 notation in formulas.〔(Dan Bricklin's VisiCalc History--The Idea )〕 When Lotus 1-2-3 was launched in 1983, taking full advantage of the expanded memory and screen of the PC, VisiCalc sales practically ended overnight. Sales imploded so rapidly that the company was soon insolvent. Lotus Development purchased the company in 1985, and immediately ended sales of VisiCalc and the company's other products. ==History== VisiCalc traces its history to a presentation that Dan Bricklin was watching while attending Harvard Business School. The professor was creating a financial model on a blackboard that was ruled with lines to create a table, and formulas and data were being written into the cells. When the professor found an error or wanted to change a parameter, he had to erase and rewrite a number of sequential entries in the table. Bricklin realized that he could replicate the process on a computer using an "electronic spreadsheet" to view results of underlying formulae. Bricklin was joined by Bob Frankston, and the pair worked on VisiCalc for two months during the winter of 1978–79, forming Software Arts. Bricklin wrote, "()ith the years of experience we had at the time we created VisiCalc, we were familiar with many row/column financial programs. In fact, Bob had worked since the 1960s at Interactive Data Corporation, a major timesharing utility that was used for some of them and I was exposed to some at Harvard Business School in one of the classes." Bricklin is referring to the variety of report generators that were in use at that time, including Business Planning Language (BPL) from International Timesharing Corporation (ITS) and Foresight, from Foresight Systems. However, these earlier timesharing programs were not completely interactive, nor did they run on personal computers. Frankston described VisiCalc as a "magic sheet of paper that can perform calculations and recalculations", which "allows the user to just solve the problem using familiar tools and concepts". Personal Software began selling it in mid-1979 for under $100, after a demonstration at the fourth West Coast Computer Faire and an official launch on June 4 at the National Computer Conference. It required an Apple II with 32K, and supported saving to cassette or disk. VisiCalc was unusually easy to use and came with excellent documentation; Apple's developer documentation cited the software as an example of one with a simple user interface. Observers immediately noticed its power. Ben Rosen speculated in July 1979 that "VisiCalc could someday become the software tail that wags (and sells) the personal computer dog". For the first 12 months it was only available for the Apple II, and became that platform's killer app. Many bought $2000 Apples to run the $100 software, even if they already owned computers. Apple's rival Tandy Corporation used VisiCalc on its own Apple IIs. Other software supported its Data Interchange Format (DIF) to share data. Bricklin and Frankston's original intention was to fit the program into 16k, but this proved impossible and 32k became necessary. Some additional features they wanted like a split text/graphics screen still had to be omitted for space reasons. However, Apple eventually began shipping all Apple IIs with 48k following a drop in RAM prices and so this was no longer an issue. The initial release supported cassette storage, but that was quickly dropped. At its release Personal Software promised ports to other computers, starting with those using the 6502 CPU, and versions appeared for the Atari 800 and Commodore PET, both of which could be done easily because those computers used the same processor as the Apple II, and large portions of code could be reused. The PET version, which contained two separate executables for 40 and 80-column models, was widely criticized for having a very small amount of worksheet space due to the developers' insistence on including their own custom DOS which used a large amount of memory (the PET only had 32k versus the Apple II's 48k). Other ports followed for the Zilog Z-80-based Tandy TRS-80 Model I, Model II, Model III, and Model 4. The TRS-80 Model I port is the only version of VisiCalc without copy protection. On most versions, this was disk-based, but the PET VisiCalc comes with a ROM chip that the user had to install in one of the motherboard's expansion ROM sockets. Another port was made to the IBM PC, and it was one of the first commercial packages available when it shipped in 1981. It quickly became a best-seller on this platform, in spite of being severely limited to be compatible with the versions from the 8-bit platforms. It is estimated that 300,000 copies were sold on the PC, bringing total sales to about 1 million copies. By 1982 VisiCalc's price had risen from $100 to $250. Several competitors appeared in the market, notably SuperCalc and Multiplan, each of which added more features and corrected deficiencies in Visicalc, but could not overcome its market dominance. A more dramatic change occurred with the 1983 launch of Lotus Development Corporation's Lotus 1-2-3, written by a former VisiCalc employee. Unlike the PC version of VisiCalc, 1-2-3 was written to take full advantage of the PC's increased memory, screen and performance. Yet it deliberately attempted to remain as compatible as possible with VisiCalc, including copying its menu structure as far as possible to allow VisiCalc users to easily migrate to 1-2-3. 1-2-3 was almost immediately successful, and by 1984 ''InfoWorld'' wrote that sales of VisiCalc were "rapidly declining", stating that it was "the first successful software product to have gone through a complete life cycle, from conception in 1978 to introduction in 1979 to peak success in 1982 to decline in 1983 to a probable death, according to industry insiders, in 1984." The magazine added that the company was slow to upgrade the software, only releasing an Advanced Version of VisiCalc for the Apple II in 1983 and announcing one for the IBM PC in 1984. By 1985 VisiCorp was insolvent, and Lotus Development acquired Software Arts. Lotus immediately ended sales of the application.〔 抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』 ■ウィキペディアで「VisiCalc」の詳細全文を読む スポンサード リンク
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