The Commodore 900 (also known as the C900, Z-8000, and Z-Machine) was a prototype microcomputer originally intended for business computing and, later, as an affordable UNIX workstation. It was to replace the aging PET/CBM families of personal computers that had found success in Europe as business machines. The project was initiated in 1983 by Commodore systems engineers Frank Hughes, Robert Russell, and Shiraz Shivji. Design The C900 was a 16-bit computer based on the segmented version of the Zilog Z8000 CPU. Initial announcements indicated the use of a 10 MHz Z8001 processor, but earlier technical documentation suggested the use of a 6 MHz part and detailed the option of a Z8070 arithmetic processing unit (APU) running at 24 MHz. The specification as announced in 1984 featured 256 KB of RAM and a 10 MB hard drive, but subsequently settled on 512 KB of RAM and a 20 MB hard drive as the minimum configuration, with 40 MB and 67 MB hard drives offered as options. Two versions of the machine were developed: a workstation with pixel graphics and a multi-user system featuring a text-only display intended to act as a server for a number of connected character-based terminals. For the text-only configuration and for lower-resolution graphical output, the system employed the MOS Technology 8563 video controller, this supporting an colour textual display or a colour graphical display. The high-resolution display option employed 128 KB of dedicated video memory and featured hardware support for blitting operations, this being employed by a graphical environment featuring "multiple overlapping windows". The C900 ran Coherent, a UNIX-like operating system, claimed in publicity as being "fully compatible with AT&T's Unix System V, version 5.2", although the Coherent system was generally regarded as merely providing a level of compatibility with Unix Version 7. Some observers found the choice of an earlier form of Unix "surprising" given the availability of more recent versions and of Zilog's commitment among other manufacturers to promote System V as the industry standard for Unix. Manufacturing of the system was to commence in 1985 at Commodore International's West Germany plant, with availability in the United States announced for the third quarter of the same year, and with pricing starting from approximately $2,700. Ultimately, only fifty prototypes were made and sold as development systems before the project was cancelled. The C900's case is similar to the Amiga 2000's but slightly larger. See also Amiga