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Notable 24-bit machines include the SDS 930 and SDS 940, the ICT 1900 series, and the Datacraft minicomputers/Harris H series. The IBM System/360, announced in 1964, was a popular computer system with 24-bit addressing and 32-bit general registers and arithmetic. The early 1980s saw the first popular personal computers, including the IBM PC/AT with an Intel 80286 processor using 24-bit addressing and 16-bit general registers and arithmetic, and the Apple Macintosh 128K with a Motorola 68000 processor featuring 24-bit addressing and 32-bit registers. The eZ80 is a microprocessor and microcontroller family, with 24-bit registers and therefore 24-bit linear addressing, that is binary compatible with the 8/16-bit Z80. The 65816 is a microprocessor and microcontroller family with 16-bit registers and 24-bit bank switched addressing. It is binary compatible with the 8-bit 6502.〔 Brett Tabke. ("A 6502 Programmer's Introduction to the 65816" ). Commodore World magazine, Issue #16. 1996. 〕 The range of unsigned integers that can be represented in 24 bits is 0 to 16,777,215 (0xFFFFFF in hexadecimal). The range of signed integers that can be represented in 24 bits is -8,388,608 to 8,388,607. Several fixed-point digital signal processors have a 24-bit data bus, selected as the basic word length because it gave the system a reasonable precision for the processing audio (sound). In particular, the Motorola 56000 series has three parallel 24-bit data buses, one connected to each memory space: program memory, data memory X, and data memory Y.〔(24-BIT. DIGITAL SIGNAL PROCESSOR. FAMILY )〕 Engineering Research Associates (later merged into UNIVAC) designed a series of 24-bit drum memory machines including the Atlas, its commercial version the UNIVAC 1101, the ATHENA computer, the UNIVAC 1824 guidance computer, etc. Those designers selected a 24-bit word length because the Earth is roughly 40 million feet in diameter, and an intercontinental ballistic missile guidance computer needs to do the Earth-centered inertial navigation calculations to an accuracy of a few feet.〔("UNIVAC 24-bit computer genealogy" )〕 == References == 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「24-bit」の詳細全文を読む スポンサード リンク
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