基于Xwindows的PCB软件，支持8层板，可输出Gerber (RS-274X) ，DRC检验包含：V1.63 V1.72Alpha 内有说明文档，请仔细阅读！
这个是基于xwindows的开源软件，英文版本，压缩包中有完整的英文说明:基更新说明如下
Pcb
an interactive
printed circuit board
layout system for X11
History
Pcb is a handy tool for laying out printed circuit boards. It was first written for an Atari ST in 1990 and ported to UNIX and X11 in 1994. I never had the intention to create another professional layout system, but to write a tool which supports people like you who do some home-developing of hardware. For this reason it has no auto-router nor auto-placement code.
The second release 1.2 included menus for the first time. This made PCB easier to use and thus a more important tool.
Release 1.3 introduced undo for highly-destructive commands, more straightforward action handling and scalable fonts. Layer-groups were introduced to group signal-layers together.
Release 1.4 provided support for add-on device drivers. Two layers (the solder and the component side) were added to support SMD elements. The handling of libraries was also improved in 1.4.1. Support for additional devices like GERBER plotters started in 1.4.4. The undo feature was expanded and the redo-feature added in 1.4.5.
Release 1.5 provides support for rats-nest generation from simple net lists. It also allows for automatic clearances around pins that pierce a polygon. A variety of other enhancments including a Gerber RS274X driver and NC drill file generation have also been added. harry eaton (haceaton@aplcomm.jhuapl.edu) was responsible for most of the changes found in this release.
Release 1.6 provides automatic screen updates of changed regions. This should elliminate most of the need for the redraw (r) key. Also some changes to what order items under the cursor are selected were made for better consistancy - it is no longer possible to accidentally move a line or line point that is completely obscured by a polygon laying over top of it. Larger objects on the upper most layers can be selected ahead of smaller objects on lower layers. These changes make operations more intuitive. A new mode of line creation was added that creates two line on 45 degree angles with a single click. The actual outline of the prospective line(s) are now shown during line creation. An arc creation mode was added. Drawn arcs are quarter circles and can be useful for high frequency controlled impedance lines. (You can have eighth circle arc if the source is compiled with -DARC45, but be aware that the ends of such arcs can never intersect a grid point). Two new flags for pins and vias were created - one indicates that the pin or via is purely a drill hole and has no copper annulus. You can only toggle this flag for vias - for elements, it must be an integral part of the element definition. The other flag controls whether the pad will be round or octagonal. There is also now a feature for converting the contents of a buffer into an element. Vias become the pins (or mounting holes), lines and arcs on the solder layer become silkscreen, and lines on the component layer become the pads. Action commands entered via the colon command entry are no longer proceeded with "a ", just type the command directly. Several bugs have also been fixed. New ones were probably introduced since extensive changes were made. harry eaton was responsible for these changes.
Release 1.6.1 adds the ability to make groups of action commands bound to a single X11 event to be undone by a single undo. Also a simple design rule checker was added - it checks for minimum spacing and overlap rules. Plus many fixes for bugs introduced with the many changes of 1.6 harry is responsible for these changes too.
who did most of the alpha and beta testing, helped to port PCB to several operating systems and platforms and corrected several typos in the manuals. In addition to these, many others donated time for bug-fixing and other important work. Some of them can be identified in the source code files. Thanks to all of them
