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INTRODUCTION
Back in 2012 I decided to write Tachyon Forth for the Parallax Propeller P8X32A or as we refer to it now simply as P1. Briefly, the reason for writing a Forth was not for Forth's sake although the appeal there was an interactive development environment resident on the P1, it was to get more out of the limited memory of the P1, but to also do so as fast as was possible for what is essentially a virtual machine with the view that serious commercial products could be produced based on the flexible P1.

In the years that followed Tachyon has proved itself, through the various original bytecode versions through to the version that now uses 16-bit word codes. The successor to the P1 is simply referred to as the P2 and although it is only available at present as an FPGA image for testing and development, nonetheless serious testing has been carried out for many years. As part of this testing I ported Tachyon across for the P2 and now Chip has announced that the P2 to be available hopefully sometime in 2018 will have 16kB of ROM of which he would only be using a couple of kB or so for the boot loader etc.

TAQOZ in ROM is implemented primarily for debugging hardware or testing out "what ifs" but it is still nonetheless a full Forth custom designed for the P2 and its hardware. As it stands the native TAQOZ wordcode can address code in a 16-bit address space while dictionary and data may reside anywhere in memory. So having software written in TWC (TAQOZ Word Code) is very compact and fast and 60kB of code represents a very very large program whereas FAT32, Ethernet servers and VGA including the Tachyon kernel and extensions would all fit in around 20kB of code space on the P1.

TAQOZ provides an interactive hardware debugging environment through its Forth console via a serial terminal emulator. Even without any "software" it is possible to exercise the hardware and write code on top of the TAQOZ dictionary, thus extending the language's vocabulary of words, all of which are a combination of various functions, constants, variables etc that are referred to by name. Parameters though are passed postfix style so that data is pushed onto a data stack and precede functions.

Please "Browse Pages" to find out more about Tachyon and TAQOZ, and how to use it and the P1 and P2 MCUs.

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Project Members:

• Peter Jakacki (admin)