P112 Single Board Computer Kit

P112 Kit

Assorted pictures of my P112 and P112s belonging to other people.

What is it?

The P112 is a stand-alone 8-bit CPU board. Typically running CP/M (tm) or a similar operating system, it provides a Z80182 (Z-80 upgrade) CPU with up to 1MB of memory, serial, parallel and diskette IO, and 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 board was last available new in 1996 by Dave Brooks. His page is here. In late 2004 on the Usenet Newsgroup comp.os.cpm, talk about making another run of P112 boards was discussed. I decided to step forward. With Dave Brooks blessing and the assistance of others, new boards were fabricated.

Nice! Tell me more!

This P112 board project is very different from the one Dave Brooks offered. The board itself is the same, but that's about all that stayed the same. The "native" operating system is now ZSDOS, an enhanced replacement for CP/M 2.2. The old DOS+ boot disk can still be used, but is discouraged. UZI-180, a Unix clone for the Z180 processor is available in a version specifically customized for the P112.

Here's the parts list. The base kit has just the board with surface-mount parts installed, a boot ROM, two RS232 driver chips, two serial port pigtails, and one power cable. You can use this Mouser Project to order most of the rest of the parts you'll need. If you want me to provide those parts in the kit, order the complete kit.

Chassis, power supply, serial terminal, serial cable, floppy cables, parallel pigtail, and floppy drives are not included.

The documentation has been pulled together into a single PDF file, updated, edited, and cleaned up. A copy of the Walnut Creek CP/M CD dated Nov 1994 is included. No permission was needed to replicate it. Another CD is provided which contains the documentation PDF and lots of other stuff that was deemed interesting (like CP/M 2.2 and UZI-180).

Another nifty thing about the P112 is that you can get an IDE interface for it. Terry Gulczynski has adapted Tilmann Reh's GIDE design to an expansion board for the P112. With this, you can connect a hard drive, CD drive, or flash drive to a P112.

The GIDE is capable of doing full 16-bit data transfers at all times. It does not rely on the drive being able to handle 8-bit data transfers. Earlier I had this wrong.

I want one, but I don't want to build it myself.

No problem! One of my cohorts, Terry Gulczynski, will build and test your P112 for you. He also has IDE interfaces. If that's what you want, select the appropriate menu item from the "Buy Now" button below. He doesn't have any P112 kits. The idea is that you pay me for a kit and I'll send it to Terry for assembly. He'll then send it to you.

Check out his website at http://stack180.com/ for more information.

How do I get it?

My inventory of P112 boards is exhausted. I'm looking into making another run in the next few months. Announcements will be made in comp.os.cpm and the cctalk mailing list at http://www.classiccmp.org/cctalk.html when something happens.


Here is the latest version of the P112 documentation.
ZSDOS manual in PDF format.
Z-System boot disk image. Dated November 30, 2005.
Z-System source code disk images. Dated November 30, 2005.
Rawrite for Windows
Windows users may find this version of Rawrite works better than the old DOS version.
Taken from RedHat Linux 6.2, this is used for copying disk image files to disks. Linux, *BSD, and other Unix users should use dd(1) instead.
PCB design database (Protel 99SE)
PCB layout (Altium 16)

The following disk images are retained for hysterical raisins.

Z-System boot disk image. Dated November 11, 2005.
Z-System boot disk image. Dated October 30, 2005.
Z-System boot disk image. Dated October 22, 2005.
Z-System boot disk image. Dated October 18, 2005.
Z-System source code disk image. Dated November 11, 2005.
Z-System source code disk image. Dated October 22, 2005.
Original boot disk image from 1996.


Here's a Sourceforge page for all sorts of information on getting the most out of your P112.
TG Consulting is where you'll find Terry Gulczynski's writings and a schedule of services. Terry created the new Z-System with ZSDOS for the P112 and updated the boot rom. He can assemble and test a P112 kit for you or supply a GIDE interface board among other things.
Dave Brooks is the designer of the P112.
Hal Bower did lots of stuff in 1996 and now to help the P112 be all it can be. Lots of CP/M tools and information can be found at his page.
Herb Johnson is another person who was helpful in getting my first batch of P112 kits ready for use. He was the first to import and sell the original GIDE interface in the United States. He also had some influence on its design. See also this page for GIDE history and other implementations of GIDE.
Professor Feedlebom was enormously helpful in getting stuff to and from the board-manufacturer and board-stuffer, and with financing.
Daves Old Computers - Disk/Software Images. Boot disks for lots of different vintage computers are here. It's not nearly the size of Don Maslin's lost archive, but it's a start.

If you have any questions or comments, feel free to email me at dave@661.org.

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This page was last updated on July 19, 2017