COMP3610: Principles of Programming Languages
Turtle Stuff

• Back to the COMP3610 Assignments page.
• Download the Assignment 2 specification
• Some sample programs.
• Download the PDPlot-2 Simulator and Disassembler.

Sample programs

• Two sample Turtle programs: twinkle.t and persp.t.
• Their compiled PDPlot-2 equivalents: twinkle.p and persp.p.
• The same programs, disassembled: twinkle.p.asm and persp.p.asm.
• The results of the programs in Postscript form, as produced by the PDPlot-2 simulator: twinkle.p.ps and persp.p.ps, for input data file persp.d.
• A collection of various other sample Turtle programs (including some illegal ones).

Download the PDPlot-2 simulator

You can download the PDPlot-2 simulator here. Strange as it may seem, it is written in Haskell.

The simulator accepts a PDPlot-2 code file and a data file, runs it on the simulator and generates a postscript file displaying the resulting image.

You will also need to download my ancient Graphics package.

You can run the simulator in ghci or compile it with ghc. When run, the simulator will ask for the path of the file containing the PDPlot-2 program produced by your compiler. It will also ask for the path of the input data file. If your program does not read from input, you still need to give a valid path here. (Apologies for my laziness.) The output will be produced as a postscript image in a file whose name is given by appending ".ps" to the program path name.

Download the PDPlot-2 disassembler

I have also written a PDPlot-2 disassembler that you may find useful for testing and debugging. Again I have written it in Haskell.

The program will ask for the path of a file containing a PDPlot-2 program, and will produce a file whose name is given by appending ".asm" to the program path name.

Be aware that the disassembler is quite primitive. It only looks at certain bit patterns and can easily interpret a data value as an instruction.