The following is from the 3/5/87 issue of Electronic Design
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            Advanced environment moves Forth to Fifth

Engineers and programmers building real-time control systems for
a fast-turnaround application need a flexible, highly interactive
programming language that delivers tight code. For many, the
Forth programming language has filled that niche. A new
implementation of that language, Fifth, combines Forth with an
advanced programming environment. Developed by Click Software,
Fifth runs on an IBM PC or a compatible.

Rather than a replacement for Forth, Fifth supplements Forth, a
virtual machine, by adding new structures and tools for Forth
program development. Moreover, its 32-bit implementation compares
favorably in speed with many 16-bit Forths. With 32 bits, it
removes the worry of mapping an application onto the Intel
microprocessor segmented architecture. With Fifth, the full 640
kbytes of PC memory is available to the programmer. A linker or
other external mechanisms are not needed to map programs onto the
PC.

A Forth-like system, Fifth combines an incremental compiler, an
internal assembler, an application editor, and an interactive
execution environment. Unlike Forth, it uses a tree structure to
hold its modules (words). Rather than simple precedence and
global scoping, access to modules -- scope -- is defined by a
path through the module tree [figure not included].

Fifth does not follow the standard Forth implementation model of
threaded code. Instead, its primitive modules are coded in
assembly, and accessed with indirect tokens -- a 32-bit pseudo
address. Unlike most Forths, users cannot alter the system
primitives; they can, however, substitute other definitions in
the directory tree.

With one keystroke, a programmer can create a turnkey application
for direct execution. All unused modules and text descriptions
are stripped from the code, minimizing its memory requirements.
For example, an application that simply prints one line will take
up a little over 2 kbytes.

The software package runs on an IBM PC XT, AT, or a compatible
with PC-DOS or MS-DOS 2.0 or greater. It requires only one floppy
disk drive and at least 128 kbytes of RAM. The program can be
configured to run from a hard disk and works with the newer DOS
file handles and file pathnames.

Fifth 2.5 is available at a cost of $150. It comes with a 30-day
unconditional guarantee and phone support.

Click Software; P.O. Box 10162; College Station, TX 77840. (409)
696-5432.