Micro Craft

Micro Craft Corporation
Company type	Private
Industry	Computer hardware
Founded	1983
Founder	Mike Carpenter
Headquarters	Dallas, United States
Products	Dimension 68000 microcomputer

Adapted from the English Wikipedia article Micro Craft, available under CC BY-SA 4.0Updated 25 July 2025

The Dimension 68000 is a microcomputer introduced by Micro Craft Corporation in 1983. It provides emulation for the Apple II, IBM Personal Computer, and several CP/M platforms through the use of coprocessor expansion cards combined with emulation software. Additionally, it functions independently as a system powered by the Motorola 68000 processor. The development was led by Mike Carpenter, Micro Craft's founder and a former executive in scientific instrumentation, who established the company in Dallas, Texas. The product remained on the market for three years and received generally favorable evaluations, although its $6,250 price tag for the complete set of coprocessor cards and emulation capabilities drew some criticism.

Main unit and keyboard

The Dimension 68000 is a desktop microcomputer with dimensions of and a weight varying between , depending on its configuration. Its chassis is constructed from steel with a cream-colored lid designed to minimize RF interference. Early versions featured a case made from Noryl thermoplastic coated internally with conductive nickel paint. The design allows users to service the unit without voiding the warranty, a deliberate decision aimed at technology professionals. The front panel houses two 5.25-inch floppy drives with black bezels and includes a reset button that can be disabled via software. On the rear panel are six expansion slots (covered with blank plates in base models), an RS-232 serial port, Centronics parallel interface, keyboard connector, joystick port, and composite video output. Power is delivered by a sturdy 100-watt, 15-amp switched-mode power supply, highly regarded for its capacity to support extensive hardware expansions.

The system’s motherboard is a four-layer printed circuit board featuring the primary CPU—a Motorola 68000 running at 8 MHz—and DIP RAM chips arranged in four banks of seventeen chips, allowing up to 512 KB of onboard memory. Promised expansions via additional cards could increase RAM up to 16 MB to fully leverage the CPU’s addressing range. The standard configuration came with 256 KB of RAM and an 8-KB ROM containing bootstrap routines, BIOS firmware, and diagnostic software. All integrated circuits are socketed to facilitate upgrades or repairs.

For storage, the Dimension 68000 includes two half-height, 5.25-inch floppy drives supporting 40 tracks each, managed by an NEC 765 controller chip compatible with multiple floppy disk formats used in IBM PC and CP/M-80 emulations. Optional expansions allowed for extra floppy drives or a full-height hard disk drive with its dedicated controller card sold separately; however, this controller was not available during the initial launch period. Included utility programs enabled reading disks from systems such as TRS-80 and Kaypro computers.

No monitor was bundled with the system; customers were expected to provide their own display devices. The computer was shipped with a Key Tronic keyboard modeled after the IBM PC/XT layout and interface standards. Video output utilized composite signals capable of supporting various text modes ranging from 20x20 to 100x50 characters and graphics resolutions up to NTSC’s horizontal resolution of 525 lines. Between mid-1984 and early 1985, an RGB digital video expansion card became available to improve display capabilities.

Expansion bus, coprocessor cards, and emulation modes

A defining feature of the Dimension 68000 was its coprocessor expansion cards that provided cross-platform functionality within one machine. Customers could alternatively purchase just the base system without these cards, though this limited immediate application usability. The proprietary expansion bus supported third-party manufacturers via an 86-pin connector delivering a 16-bit data bus, 24-bit address lines, as well as DMA and interrupt signals per slot. Disk drive signals were also routed through this bus, enabling expansion cards to add disk controllers beyond the built-in NEC 765 chip—for example, on the Apple II coprocessor card.

Promoted as a "hybrid emulator," the Dimension 68000 relied on coprocessors to run most software within their respective emulation environments while delegating interrupts related to display management and disk input/output—tasks beyond coprocessors’ standalone capabilities—to the Motorola 68000 processor.

Micro Craft released three main expansion cards: one for IBM PC emulation, another for Apple II emulation, and a CP/M card based on the Zilog Z80 processor suitable for systems like Kaypro and Osborne 1. Operating these cards required booting from an "emulation master" disk; once loaded, users could initiate the desired emulation mode through command-line prompts.

Apple II card

The Apple II coprocessor card was built around an MOS 6512 processor, selected instead of the original MOS 6502 due to its support for an external clock, making it more appropriate for multiprocessor environments such as the Dimension 68000. This card incorporated a specialized floppy disk controller that allowed half-step motor movements, a feature critical for certain copy-protection methods commonly employed by Apple II software developers. Nonetheless, some timing-dependent protections occasionally led to difficulties in loading software because of how the Motorola 68000 handled interrupts.

In contrast to IBM emulation mode, which initiates with a straightforward command, Apple II emulation demands multiple parameters that define hardware configurations like the presence of a printer, the quantity of disk drives, keyboard type, and display settings.

Users are responsible for providing their own Apple DOS or ProDOS operating system. After booting into Applesoft BASIC, the interpreter fully supports BASIC syntax including commands such as PEEK and POKE. The coprocessor card simulates a full array of Apple II peripheral cards distributed across several virtual slots—Language Card (slot 0), parallel interface (slot 1), serial interface (slot 2), 80-Column Text Card (slot 3), floppy controller with two emulated drives (slot 6), and hard drive controller (slot 7). These peripherals operate as intended within Applesoft BASIC; for instance, activating the 80-Column Text Card requires typing at the prompt.

IBM PC card

Equipped with an Intel 8086 processor running at 7.3 MHz, the IBM PC coprocessor card operates at nearly twice the speed of the IBM PC's original 4.77-MHz Intel 8088. This increased clock rate compensates for performance reductions caused by software emulation and interrupt processing on the Motorola 68000, enabling spreadsheet computations to run at speeds similar to those on an authentic IBM PC.

The default emulation program on the "emulation master" disk supports an IBM PC setup with a CGA display capable of showing text in an 80-column by 25-row format. Additionally, three other emulation programs are included: one offering CGA with 40x25 text mode, another providing Monochrome Display Adapter support with 80x25 text but no graphics, and an experimental enhanced version (1.18) that introduced direct I/O access to the NEC 765 floppy controller and extended RS-232 serial port functionality; however, this version was not fully debugged as of September 1984. All four programs launch without requiring arguments by default, thereby preserving maximum RAM availability for the virtual machine—for example, leaving approximately 412 KB accessible on systems equipped with 512 KB of RAM.

Users could specify arguments to restrict memory usage (), modify character brightness (), or adjust hardware settings through software equivalents of IBM PC motherboard DIP switches ().

A README file on the emulation disk documented known issues as of September 1984: absence of fallback to IBM Advanced BASIC without a boot disk due to licensing constraints, no support for joystick ports, lack of direct I/O access to the NEC 765 except in , and nonfunctional channel 2 on the PC speaker. By November 1984, channel 2 remained inactive, resulting in audio problems in titles like Microsoft Flight Simulator, where sound-related interrupt requests were disregarded.

Exiting IBM PC emulation mode was possible by pressing Control-Alt-Delete or using the reset button on the Dimension 68000 system.

Z80 CP/M card

The CP/M coprocessor card is driven by a 4-MHz Zilog Z80A processor and comes equipped with CP/M 2.2 tailored for the Z80, accompanied by a Digital Research manual. Included is the "emulation master" disk, which contains four emulator programs capable of managing up to 64 KB of RAM, dual 5.25-inch floppy drives, a parallel port, and ADM-3 terminal displays. These emulators replicate the environments of the Kaypro II (), Osborne 1 (), and S-100-based Cromemco systems (). The emulator simulates a standard Z80 CP/M configuration and supports drive letters beyond , including a RAM drive at , unlike the other emulators which are confined to and .

Native software

The Dimension 68000's original operating system is CP/M 68K, a Motorola 68000 adaptation created by Digital Research prior to the Z80 becoming the dominant CP/M platform. Alternative multi-user operating systems such as Mirage and SofTech Pascal were available to overcome the single-user constraints of CP/M. Micro Craft repeatedly announced plans to port Unix System V and eventually introduced a four-user Unix version in October 1985, which required additional hardware purchases including terminals and hard drives ranging from 20 to 50 MB, priced between US$9,995 and $15,995.

CP/M 68K includes a suite of utilities such as the file transfer tool PIP, the Motorola 68000 debugger DDT-68K, a file system statistics utility , along with a C compiler for the Motorola 68000, linker loader, and assembler.

Unibasic, a BASIC variant developed by Dallas-based RD Software specifically for the Dimension 68000, leverages the full 16 MB address space of the Motorola 68000. It draws heavy inspiration from Applesoft BASIC, sharing peripheral memory addressing conventions while introducing advanced capabilities like VARPTR (variable pointer), dynamic screen formatting through Mode statements, and Call statements supporting up to fifteen parameters.

At least one third-party software vendor supported this platform: Cademic, Inc. launched CLYDE (Custom Logic You Design Easily), a VLSI circuit design application, in May 1984.

Development and release

Mike Carpenter, former president of Scientific Machines, led the primary development of the Dimension 68000 following Micro Craft Corporation’s founding in Dallas, Texas, in November 1981. Carpenter’s vision was to engineer a highly compatible system capable of seamless interoperability across popular platforms, powered by a Motorola 68000 microprocessor and designed to avoid rapid obsolescence. To achieve greater flexibility beyond existing standards, a proprietary bus architecture was created. Carpenter also enlisted talent from IBM and Apple to enhance the system’s emulation features.

The initial product launch occurred in October 1983 with a base price of $3,995 and $6,250 for a complete emulation package. Micro Craft established an extensive dealer network comprising approximately 80–90 outlets distributing around 250 units nationwide. By April 1984, this network was streamlined to 77 dealers. The Dimension 68000 also expanded internationally through partnerships with Tashkl Computer Services in the UK and Popular Electronic Products in Canada.

Micro Craft filed for Chapter 11 bankruptcy protection in early 1985 but reemerged under businessman Donald F. Bynum within three months, maintaining sales operations for an additional year. Although it never gained substantial market share, the Dimension 68000 was acquired by an Arkansas-based holding company and rebranded as Dimension Electronics in 1987. This successor launched the New Dimension 68000 model featuring improved Macintosh emulation; however, its market presence was brief and units remain uncommon. Overall, the product’s lifecycle was relatively short-lived.

Reception

By April 1984, early marketing efforts had attracted more than 50,000 inquiries, primarily fueled by the system’s emulation capabilities. By the middle of 1985, Micro Craft redirected its strategy to emphasize utilizing the Motorola 68000 processor’s native mode in conjunction with coprocessors.

Pre-launch evaluations commended the Dimension for its extensive emulation support and dependable hardware functionality. Jim Heid from Microcomputing praised its seamless operation and efficient thermal management. Steve Rimmer of Computing Now! admired the sophisticated technology and rapid emulation speeds but pointed out that its steep price rendered it less practical compared to genuine clones for customers seeking replacement machines.

Peter Bright of Personal Computer World acknowledged the device’s technical advancements yet questioned its suitability for the market, criticizing the documentation as unfriendly to novices and noting limited operating system compatibility beyond CP/M-86. Rick Cook from Popular Computing recognized the strong native processing power and competitive pricing among 68000-based systems but observed that the cost of complete emulation packages was high relative to acquiring separate dedicated units.

Stephen T. Satchell of InfoWorld described native mode performance as modest and emulation as sufficient but imperfect for certain uses, summarizing the Dimension as a "jack of all trades, master of none." He suggested prioritizing enhancements in core processing rather than emulation features. John J. Anderson from Creative Computing shared similar views, expressing dissatisfaction with the emulators while commending the machine’s superior native-mode performance in Fortran and Pascal when compared to IBM PCs.

In summary, although the Dimension 68000 demonstrated an innovative business model through its multi-platform compatibility and advanced hardware engineering, its market penetration was constrained by pricing issues and execution difficulties within a highly competitive sector.

References