The Leading Edge Model D is an IBM clone 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 sold well for several years, until a dispute with 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 have no turbo switch and run only at 4.77 MHz, while a few of the later ones (seemingly very rare) are 7.16 MHz only. Four models are known: DC-2010, DC-2011, DC-2010E, and DC-2011E. The "E" seems to correlate with the capability of running at 7.16 MHz. The addition of the Intel 8087 floating point unit (FPU) coprocessor is supported in all Leading Edge Model D revisions with an onboard 40-pin DIP socket. Unlike the IBM PC and IBM PC/XT, the Model D integrates video, the disk controller, a battery backed clock (real-time clock or RTC), serial, and parallel ports directly onto the motherboard rather than putting them on plug-in cards. This allows the Model D to be half the size of the IBM PC, with four free ISA expansion slots compared to the PC's one slot after installing necessary cards. The motherboard came in eight different revisions: Revision 1, 5, 7, 8, CC1, CC2, WC1, and WC2. Revisions 1 through 7 are usually found in models DC-2010 and 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 is a nonstandard form factor, so replacing the motherboard with an off-the-shelf upgrade is not possible. The Model D is preinstalled with 256, 512, or 640 KB of RAM.