Pencil and Paper Interpreter is a simulation environment for the Pencil and Paper computer described in Chapter 5 of The Computer Continuum by Kurt Lauckner and Mildred Lintner, 2nd Edition, (c) 2001 Prentice Hall, Inc.  It was originally implemented by  Dr. Martin C. Carlisle and Maj Al White of the United States Air Force Academy  Department of Computer Science. 

The environment window is shown below:

Programming the Pencil and Paper Computer

A Pencil and Paper program is a sequence of instructions (see Table 5.4.2 for the instruction set).  The data section of the program should be at the bottom.  (In the above picture, addresses 30 and 31 contain data, and addresses 0-5 contain the program).  At any time, the user can change the program by clicking on the appropriate Value in the Value column and entering a different 8 digit binary number.  This program can be saved and reloaded using the Load and Save Program choices from the File menu.  If desired, you can set the PC by clicking on the value in the bottom right corner of the screen.  Furthermore, you can shift the instructions down, or delete an instruction and shift the remaining instructions up by selecting the appropriate choice from the File menu.  The operands of all instructions from the current PC to the end of the program section (determined by two consecutive STOP instructions) will be incremented or decremented accordingly.

Changing the Accumulator

The value of the Accumulator can be changed by clicking on its value and entering a 14 digit binary number in the dialog that appears.

Running the program

"Reset" resets the PC to 0 (the value of the program counter is displayed in the lower right corner, and as a red arrow next to the instruction about to be executed).  "Do Next" will fetch and execute the next instruction, but does nothing if the computer has executed a stop instruction.  "Run until Stop" repeatedly fetches and executes instructions.  The speed of simulation may be adjusted using the slider.  The simulation stops when the user pushes stop, or the Pencil and Paper computer does a STOP instruction.  To start again, push "Reset".