The P112 is a stand-alone 8-bit CPU board. Typically running

CP/M CP/M, originally standing for Control Program/Monitor and later Control Program for Microcomputers, is a mass-market operating system created in 1974 for Intel 8080/ 85-based microcomputers by Gary Kildall of Digital Research, Inc. Initial ...

or a similar operating system, it provides a

Z80182 The Zilog Z80182 is an enhanced, faster version of the older Z80 and is part of the Z180 microprocessor family. It's nicknamed the ''Zilog Intelligent Peripheral Controller'' (ZIP). It has the following features: * Two ESCC (enhanced serial cha ...

(

Z80 The Z80 is an 8-bit microprocessor introduced by Zilog as the startup company's first product. The Z80 was conceived by Federico Faggin in late 1974 and developed by him and his 11 employees starting in early 1975. The first working samples were ...

upgrade) CPU with up to 1MB of SRAM memory, 32KB of in-system programmable flash ROM, serial, parallel and diskette IO, and a realtime clock, in a 3.5-inch drive form factor. Powered solely from 5V, it draws 150mA (nominal: not including disk drives) with a 16MHz CPU clock. Clock speeds up to 24.576MHz are possible. The P112 is notable because it was the first of the hobbyist single board computers to reach the production stage. The P112 hobbyist computers were relatively widespread and inspired other hobbyist centered home brew computing projects such as

N8VEM N8VEM was a homebrew computing project. It featured a variety of free and open hardware and software. N8VEM builders made their own homebrew computer systems for themselves and shared their experiences with other homebrew computer hobbyists. N8VEM h ...

home brew computing project. The P112 project still maintains many devoted enthusiasts and has an online repository of software and other information. The P112 computer originated as a commercial product of "D-X Designs Pty Ltd" of

Australia Australia, officially the Commonwealth of Australia, is a Sovereign state, sovereign country comprising the mainland of the Australia (continent), Australian continent, the island of Tasmania, and numerous List of islands of Australia, sma ...

in 1996. As of August 2016, Dave Brooks has released the hardware and software components of P112 into the public domain, under the

GPL The GNU General Public License (GNU GPL or simply GPL) is a series of widely used free software licenses that guarantee end users the four freedoms to run, study, share, and modify the software. The license was the first copyleft for general us ...

. The PCB layout is available in the original Protel format, and translated into the current Altium Designer 16 format, which many PCB fabricators can accept. The P112 board was last available new in 1996 by Dave Brooks. In late 2004 on the Usenet Newsgroup comp.os.cpm, talk about making another run of P112 boards was discussed. David Griffith decided to produce additional P112 kits with Dave Brooks' blessing and the assistance of others. In addition Terry Gulczynski makes additional P112 derivative hobbyist home brew computers. Hal Bower was very active in the mid 1990s on the P112 project and the commercial "Banked/Portable BIOS"

-compatible operating system was sold for the P112 between 1992 and 1999. It has now been released as open source under the GPL license.

References

{{Reflist Single-board computers