Papilio Forth

Papilio Forth is a rudimentary interactive Forth to run on Papilio One and Papilio Pro FPGA boards.

Papilio Forth is a feasibility study that shows priniples but does not implement a complete Forth development system.

Papilio Forth executes Forth program on a variation of James Bowman's J1 FPGA soft core (see also J1 on Github) running at 66 MHz. It communicates with a host system using a serial line at a default speed of 9600 Bits/s.

Prerequisites

• GNU make for job control
• Java JDK7 or JDK8 for compiling the cross compiler and other tools
• Xilinx ISE to generate the FPGA bit stream (Papilio One: ISE 13.4, Papilio Pro: ISE 14.7)
• Papilio-Loader to download the bitstream to the FPGA

Directry Structure

Papilio-Forth
├── firmware
│   ├── bin		cross compiler executables (generated)
│   ├── forth		rudimentry Forth kernel
│   └── src		Forth cross compiler written in Java, assembler, debugger, simulator
└── vhdl  
    ├── src		Verilog projects for J1 and UART for Papilio One and Papilio Pro 
    └── test		testbenches

How to build Papilio Forth

1. Build the cross compiler and appendant tools:

   make -C firmware tools

2. Build the Forth image for the J1 processor:

   make -C firmware images

3. Create the J1 bit stream:

- **Papilio One**

  Start Xilinx ise on project `vhdl/papiolo-one-forth.xise`
  choose `Generate Programming File` on the main component. This generates `main.bit` w/o memory initialization.
  
    make -C vhdl final.bit

  generates `final.bit` from `main.bit` including the Forth image (`memory.mem`) built in step 2 as initial memory.
 
- **Papilio Pro**

  Start Xilinx ise on project `vhdl/papiolo-one-forth.xise`
  choose `Generate Programming File` on the papilio-pro-forth component. This generates papilio_pro_forth.bit
  including the Forth image (`memory.hex`) built in step 2 as initial memory.

4. Load the complete bit stream (J1 and memory) into the FPGA:

   sudo papilio-prog -v -f final.bit

   or

   sudo papilio-prog -v -f papilio_pro_forth.bit

   depending on which image you want to load. You might want to use the pre-built images for a quick start.

5. Connect to Papilio Forth:

   screen /dev/tty.usbserial 9600

   or similar. Papilio Forth should show the prompt

   Welcome to Papilio Forth

   ?>

   If you only see the ?> prompt issue a 0 >r and press the enter key to reboot the system.

May the Forth be with you.