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The Leading Edge Model D was an IBM clone computer first released by Leading Edge Hardware in July 1985. It was initially priced at $1,495 configured with dual 5.25" floppy drives, 256 KB of RAM, and a monochrome monitor. It was manufactured by South Korean conglomerate Daewoo and distributed by Canton, Massachusetts-based Leading Edge. Engineer Stephen Kahng spent about four months designing the Model D at a cost of $200,000. Kahng later became CEO of Macintosh clone maker Power Computing. In August 1986, Leading Edge cut the price of the base model by $200, to $1,295, and increased the base memory of the machine to 512 KB. The Model D was an immediate success, selling 100,000 units in its first year of production. It continued to sell well for several years, until a dispute with its dealers forced Leading Edge into bankruptcy in 1989. ==Hardware== The Model D initially featured an Intel 8088 microprocessor at 4.77 MHz, although later models had a switch in the back to run at 4.77 MHz (normal) or 7.16 MHz (high). Earlier models had no turbo switch and ran only at 4.77 MHz, while a few of the later ones (seemingly very rare) were 7.16 MHz only. Three models are known: DC-2011, DC-2010E, and DC-2011E. The "E" seems to correlate with the capability of running at 7.16 MHz. Unlike the IBM PC and IBM PC/XT, the Model D integrated video, the disk controller, a battery backed clock, serial and parallel ports directly onto the motherboard rather than putting them on plug-in cards. This allowed the Model D to be half the size of IBM's models.〔 There were four full-length ISA expansion slots available.〔Byte Sept. 1986〕 The motherboard came in eight different revisions: Revision 1, 5, 7, 8, CC1, CC2, WC1, and WC2. A list of motherboard part numbers and revision numbers can be found (here. ) Revisions 1 through 7 were usually found in model DC-2011, with revisions 8 through WC2 being either in 2010E or 2011E. WC1 (presumably also WC2) is 7.16 MHz only. Due to its tight integration, the Model D motherboard was a nonstandard form factor, so replacing the motherboard with an off-the-shelf upgrade was not possible. They came preinstalled with 256, 512, or 640 KB of RAM. Lower-capacity machines were user upgradeable to 640 KB. Motherboard revisions 7, 8, WC1 and WC2 came with 768 KB of RAM installed (640 KB available to the user). Some models featured a monochrome/CGA selection switch, with a single port used for both modes. Some models had both a Monochrome and a CGA port, also with a switch to change modes (and ports).〔 The Model D computers supported a special extended graphics mode: 640x200. The buyer had the choice between a floppy disk model and a fixed disk (hard disk) model. The floppy disk model had one or two 360 KB drives, so that the user could run MS-DOS programs on the primary drive and work with files on the secondary drive, if equipped.〔 The fixed disk model had one 360 KiB floppy drive and either a 10 MB, 20 MB, or 30 MB hard disk. The model with the 20 MB fixed disk was initially released in February 1986 at a cost of $1,895. Leading Edge dealers had difficulty keeping the 20MB model in stock.〔 At the time, a Tandy 1200 equipped with a 10MB drive sold for $1999. The buyer also had a choice between an amber or a green monochrome CRT monitor. 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「Leading Edge Model D」の詳細全文を読む スポンサード リンク
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