The
Leading Edge Model D was an IBM clone
computerA computer is a machine that manipulates data according to a set of instructions.Although mechanical examples of computers have existed through much of recorded human history, the first electronic computers were developed in the mid-20th century . These were the size of a large room, consuming as...
released by
Leading Edge HardwareLeading Edge Hardware Products, Inc. was a computer manufacturer in the 1980s and the 1990s. They were based in Westborough, Massachusetts.-History:...
during or before 1986.
The Model D featured an
Intel 8088The Intel 8088 microprocessor was a variant of the Intel 8086 and was introduced on July 1, 1979. It had an 8-bit external data bus instead of the 16-bit bus of the 8086. The 16-bit registers and the one megabyte address range were unchanged, however...
microprocessorA microprocessor incorporates most or all of the functions of a central processing unit on a single integrated circuit . The first microprocessors emerged in the early 1970s and were used for electronic calculators, using binary-coded decimal arithmetic on 4-bit words...
at 4.77 MHz, although many 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
Leading Edge Model D was an IBM clone
computerA computer is a machine that manipulates data according to a set of instructions.Although mechanical examples of computers have existed through much of recorded human history, the first electronic computers were developed in the mid-20th century . These were the size of a large room, consuming as...
released by
Leading Edge HardwareLeading Edge Hardware Products, Inc. was a computer manufacturer in the 1980s and the 1990s. They were based in Westborough, Massachusetts.-History:...
during or before 1986.
Hardware
The Model D featured an
Intel 8088The Intel 8088 microprocessor was a variant of the Intel 8086 and was introduced on July 1, 1979. It had an 8-bit external data bus instead of the 16-bit bus of the 8086. The 16-bit registers and the one megabyte address range were unchanged, however...
microprocessorA microprocessor incorporates most or all of the functions of a central processing unit on a single integrated circuit . The first microprocessors emerged in the early 1970s and were used for electronic calculators, using binary-coded decimal arithmetic on 4-bit words...
at 4.77 MHz, although many 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.
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.
They came preinstalled with 256 or 512
KBThe kilobyte is a unit of digital information storage equal to either 1,000 bytes or 1,024 bytes , depending on context....
of RAM, user upgradeable to 640 KB. Some had the full 640 KB preinstalled. Some of the later ones were upgradeable to 768 KB.
Some models featured a monochrome/
CGAThe Color Graphics Adapter , originally also called the Color/Graphics Adapter or IBM Color/Graphics Monitor Adapter, introduced in 1981, was IBM's first color graphics card, and the first color computer display standard for the IBM PC....
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 diskA floppy disk is a data storage medium that is composed of a disk of thin, flexible magnetic storage medium encased in a square or rectangular plastic shell. Floppy disks are read and written by a floppy disk drive or FDD, the initials of which should not be confused with "fixed disk drive," which...
model and a fixed disk (
hard diskA hard disk drive is a non-volatile storage device that stores digitally encoded data on rapidly rotating platters with magnetic surfaces. Strictly speaking, "drive" refers to the motorized mechanical aspect that is distinct from its medium, such as a tape drive and its tape, or a floppy 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
MBThe megabyte is an SI-multiple of the unit byte for digital information storage or transmission and is equal to 10
6 bytes. However, due to historical usage in computer-related fields it is still often used to represent 2
20 bytes. In rare cases, it is used to mean...
, 20 MB, or 30 MB hard disk.
The buyer also had a choice between an amber or a green monochrome CRT monitors.
The price was about $1600.
Software
The unit came with
MS-DOSMS-DOS is an operating system developed by Microsoft. It was the most commonly used member of the DOS family of operating systems and was the main operating system for personal computers during the 1980s. It was preceded by M-DOS , designed and copyrighted by Microsoft in 1979...
3.10 or later, and a special edition of
GW-BASICGW-BASIC was a dialect of BASIC developed by Microsoft from BASICA, originally for Compaq. It is compatible with Microsoft/IBM BASICA, but was disk based and did not require the ROM BASIC. It was bundled with MS-DOS operating systems on IBM PC compatibles by Microsoft. Microsoft also sold a BASIC...
to support the extended graphics mode.
It also came with a diagnostics disk. This disk contained a diagnostics program, and PARK.COM, a utility used to park the hard drive heads when the computer was to be moved. Most models also came with a word processing program developed by Leading Edge titled
Leading Edge Word Processor, commonly referred to by its acronym 'LEWP'.
The computer supports the
Microsoft WindowsMicrosoft Windows is a series of software operating systems and graphical user interfaces produced by Microsoft. Microsoft first introduced an operating environment named Windows in November 1985 as an add-on to MS-DOS in response to the growing interest in graphical user interfaces...
operating system up to
version 3.0Windows 3.0 is the third major release of Microsoft Windows, and was released on 22 May 1990. It became the first widely successful version of Windows and a powerful rival to Apple Macintosh and the Commodore Amiga on the GUI front...
, as it is the last version of Windows to support
Real ModeReal mode, also called real address mode, is an operating mode of 80286 and later x86-compatible CPUs. Real mode is characterized by a 20 bit segmented memory address space and unlimited direct software access to all memory and I/O addresses and peripheral hardware...
.
Significance
The Model D, along with the
Tandy 1000The Tandy 1000 was the first in a line of more-or-less IBM PC compatible home computer systems produced by the Tandy Corporation for sale in its Radio Shack chain of stores.-Overview:...
and
Epson EquityThe Epson Equity series of IBM Compatible Personal Computers was manufactured from 1985 until the early '90s by Epson Inc. Epson was well known for its dot matrix printers at the time and the Equity series represents their entry into the growing PC compatible market...
series, was one of the first
IBM PC CompatibleIBM PC compatible computers are those generally similar to the original IBM PC, XT, and AT. Such computers used to be referred to as PC clones, or IBM clones since they almost exactly duplicated all the significant features of the PC architecture, facilitated by various manufacturers' ability to...
computers to become popular for home use. Previously, MS-DOS and IBM Compatibles were almost exclusively used in businesses, with the home market dominated by
CommodoreCommodore, the commonly used name for Commodore International, was a US electronics company based in West Chester, Pennsylvania which played a vital role in the development of the home/personal computer industry in the 1980s. The company is also known under the name of its R&D operation, Commodore...
, Apple Inc. and
AtariAtari is a corporate and brand name owned by several entities since its inception in 1972. It is currently owned by Atari Interactive, a wholly owned subsidiary of the French publisher Infogrames Entertainment SA ....
. For years afterward, many home-oriented software packages for the PC specifically cited these models as compatible hardware.