Riscy Pygness – Pygmy Forth for the ARM

Riscy Pygness is a 32-bit multitasking Pygmy Forth for the ARM. It includes full source code for both the host (your desktop PC) and target (your ARM development board). The license is BSD/MIT-like so you can do (nearly) anything with it.

It is aimed at relatively small embedded systems rather than desktop systems or large embedded systems running an operating system (OS).

Riscy Pygness is a stand-alone system that is its own multitasking OS. It can run in about 4 K bytes of flash and about 1.5 K bytes of RAM. The size can be reduced further depending on your needs. This makes it suitable for use in even the smaller ARM variants such as the NXP LPC2101, LPC2102, and LPC2103. It can address the full 4 GB address space, so it can take advantage of all the flash and RAM available in even the larger variants.

During development, the host communicates with the target via a serial port. The host provides the smart terminal and the compiling services. The host can generate a new, customized Forth image for the target.

The Forth itself runs on the target but you interact with it by typing commands on the host, much as you would with a Forth running locally on the host.

As you type each word (command) at the terminal, the word is looked up on the host which then sends a request to the target to execute the word. Numbers typed at the terminal are sent to the target to be put on the target's data stack. Word headers are kept on the host, not the target, and all compilation work is done on the host.

The host and the target, working together, provide the effect of a fully interactive Forth running on the target while conserving the target's limited resources.

Riscy Pygness

version released November 12, 2010

• http://pygmy.utoh.org/riscy/riscypygness-20101113.tar.bz2 (153K)
• http://pygmy.utoh.org/riscy/riscypygness-20101113.tar.bz2.md5

After downloading into your home directory, create a working directory and uncompress the files there, e.g.,

$ cd                                           # move to your home directory
$ mkdir riscy                                  # make a working directory
$ cd riscy                                     # move to the working directory
$ tar -xjvf ../riscypygness-20101113.tar.bz2   # uncompress the files

The Manual

the manual applies to the ARM as well as the ARM Cortex versions of Riscy Pygness

The Bundle of Tools

(the GNU toolchain to cross assemble for the ARM, Tclkit, lpc21isp).

Note, these tools were compiled under Ubuntu 10.04 i386 32-bit. They might work on Ubuntu 10.10 i386 32-bit or under other Linux distributions, possibly even on 64-bit versions if the 32-bit libraries are installed. Please let me know if you run it successfully on any Linux distribution other than 32-bit i386 Ubuntu 10.04.

the binary

http://pygmy.utoh.org/riscy/arm-toolchain.tar.bz2 (28M)

its checksum

http://pygmy.utoh.org/riscy/arm-toolchain.tar.bz2.md5

After downloading above, run

$ md5sum -c arm-toolchain.tar.bz2.md5   

to verify the checksum, then

$ sudo tar -xjvf arm-toolchain.tar.bz2 --absolute-names --keep-old-files 

to uncompress and install in the standard locations (under /usr/local/).

the source

since some of the above is licensed under the GNU GPL, the full source code for the GPL'd files is also available here. You probably do not need to download it unless you wish to compile the tools yourself.

• http://pygmy.utoh.org/riscy/binutils-2.20.1.tar.bz2 (17M)
• http://pygmy.utoh.org/riscy/gdb-7.2.tar.bz2 (18M)
• http://pygmy.utoh.org/riscy/lpc21isp-1.79.tar.gz (53K)

See the latest version of the manual.

Kernel images to be burned into flash on the ARM are included in the zip file for 4 Olimex boards.

• Olimex LPC-P2106 board
• Olimex LPC-P2103 board
• Olimex LPC-P2378 board
• Olimex LPC-P2294 board

It is very easy to add support for other LPCxxx-based boards and should be fairly easy to port to other ARM 7 variants.

I am running on Linux, typically Debian or Ubuntu.

Any Linux or Unix or Unix-like operating system that can run Tcl/Tk (i.e., all of them) should work great.

If you are not currently running Linux or Unix, you can try out Riscy Pygness from a live CD (details in the manual).

If you prefer to run on a Microsoft operating system, you probably can do so, but everything is likely to be just a little more difficult. It might be worth setting up a spare machine (or booting from a Live CD) to have Linux available. The manual has a section describing such alternatives.

If you try Riscy Pygness, feel free to email me at frank@pygmy.utoh.org for with suggestions or questions. Your feedback will help me further improve the system and manual.