Scheme Editor


    The program automatically saves the schematic on close and screen rotation.  There is a .bak file that contains the previous backup. It is possible to save the schematic manually from the menu. Rotating the device restarts the program in editor mode.


    Touch the screen at any point and immediately move your finger. 


    A short touch on free space puts the cursor there.  Long press switches the cursor to selection mode. The cursor is red now.


    First put the cursor somewhere. This button opens the device group selection menu.

    Now select a group e.g. Gates.

    Select a gate or press back button here.


Touch an IO or a wire. It becomes red. Select another IO or wire that is not connected to the first selection.


    Two selection modes are available in main menu. They are "Enlarge selected" and "Do not enlarge selected". The default is "Do not enlarge selected".

In the case of "Do not enlarge selected" any object and one or more IO of a device can be selected directly.

The "Enlarge selected" mode allows no direct IO selection. The parent device has to be selected first.

In the editor mode a single touch selects the object. The selected object becomes red and buttons appear near the left and right borders. If the first selected object is wire or IO then the next selection of a similar object makes connection between them.

It is possible to select more than one objects but always the last one may be enlarged. Long press on free area switches multiple selection mode until the end of the press. The cursor is red and appears above the touched point. Move the cursor across the objects you want to select.


    Touching a selected object the selection disappears. Press this button to cancel all selections.


Select an input or an output or a wire. Push NET button.

The connected wires, the net will be selected.


    Select some objects and press DEL button


     The last 7 steps can be undone.


 Press this to redo previously undone actions.


    Selected objects can be locked. In this case after the move or rotation of the object the program tries to reroute connections. If the reroute failed then move or rotate the object to another position.


    If a single selected object is locked it can be unlocked.


    Touch a selected object and immediately move your finger. 


    Some objects can be rotated.


    Select some objects and put the cursor somewhere. Usually it is faster cloning a device than selecting it from menu.

   The maximum number of gate inputs is 8. Some types may not have so many of course. Select a gate and press this.   Inputs can be removed as well. Select a gate and select some of its inputs. Press DEL


    Flip flop inputs can be inverted. Select a flip flop and select some of its inputs. 


    Select a gate, flip flop, probe or switch. Press TIME button


    Select a probe or label or comment object. 


  Select a box and press INCLUDE. Select .s or .v file from popup menu.
If the circuit is given as schematic then the file extension is .s
If the extension is .v then the file contains a Verilog module.
Only a small subset of Verilog is allowed at the moment. 
The two built in demo modules use this subset:

module smpl_circuit (A,B,AND,NAND,OR,NOR,XOR,XNOR,BUF,NOT);
 input A,B;
   and #10 g0(AND,A,B);
   nand #10 g1(NAND,A,B);
   or #10 g2(OR,A,B);
   nor #10 g3(NOR,A,B);
   xor #10 g4(XOR,A,B);
   xnor #10 g5(XNOR,A,B);
   buf #10 g6(BUF,A);
   not #10 (NOT,A);

module circuit(A,B,C,y);
 input A,B;
 output y;
 wire e;
   and #30 g1(e,A,B); 
   or #30 g2(y,e,C);

    Select two or more objects and press  vertical
or  horizontal alignment

Main menu


    Saves the current scheme and creates an empty new.


    Saves the current scheme.

Save as

    Renames and saves the scheme.

Spike detection

    Opens a pop up window and asks for the width of the spikes. The default width is 0 that disables detection.

Enable FF check

    If enabled then violation of setup, hold, recovery and resume times are detected and displayed.

Enable wire level display

    If enabled then the colors of the wires show the current logical levels. It is very time consuming.


   Can be Auto, Portrait, Landscape. If set to auto the rotation causes immediate switch to editor mode and save and restore, 


   Moves the scheme to the center of the board.

Enable diagonal

   The auto router works with diagonal wires. Manual editing is not possible.

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