Xschem is a schematic capture program, it allows creation of
    hierarchical representation of circuits with a top down approach . 
    By focusing on interfaces, hierarchy and instance properties a 
    complex system can be described in terms of simpler building blocks.
    A VHDL or Verilog or Spice netlist can be generated from 
    the drawn schematic, allowing
    the simulation of the circuit. Key feature of the program is its
    drawing engine written in C and using directly the Xlib drawing
    primitives; this gives very good speed performance, even on very
    big circuits. The user interface is built with the Tcl-Tk toolkit,
    tcl is also the extension language used.
| date | version | notes | 
| 19980804 | 0.1 | First draft | 
| 20040202 | 1.0 | First release | 
| 20161203 | 2.0 | Second release, uploading on sourceforge | 
| 20200217 | 2.9.5 | 2.9.5 release, uploading on repo.hu and sourceforge | 
| 20210211 | 2.9.9 | 2.9.9 release, skywater 130nm pdk integration | 
| 20210911 | 3.0.0 | 3.0.0 release, now including windows binary distribution | 
| 20220721 | 3.1.0 | 3.1.0 release, ability to display simulation graphs and embeded images/logos | 
| 20230521 | 3.4.0 | 3.4.0 release, instance based implementation selection, graph exporting in svg and pdf, much more schematic annotation (live transient/sweep annotation), schematic/symbol PCELLS | 

