Hewlett-Packard During his final year at the university, Sassenrath joined
Hewlett-Packard's Computer Systems Division as a member of the
Multi-Programming Executive (MPE)
file system design group for
HP 3000 computers. His task was to implement a
compiler for a new type of control language called
Outqueue—a challenge because the language was both descriptive and procedural. A year later, Sassenrath became a member of the MPE-IV OS
kernel team and later part of the HPE kernel group. While at HP Sassenrath became interested in minimizing the high complexity found in most operating systems of that time and set out to formulate his own concepts of a
microkernel-based OS. He proposed them to HP, but found the large company complacent to the "smaller OS" ideas. In late 1981 and early 1982, Sassenrath took an academic leave to do atmospheric physics research for
National Science Foundation at
Amundsen–Scott South Pole Station. Upon returning, Sassenrath reached an agreement with HP to pursue independent research into new areas of computing, including
graphical user interfaces and
remote procedure call methods of distributed computing. Later in 1981, impressed by the new computing ideas being published from
Xerox PARC, Sassenrath formed an HP project to develop the modern style of window-based
mouse-driven
GUIs. The project, called
Probus (for professional business workstation) was created on a prototype
Sun Microsystems workstation borrowed from
Andy Bechtolsheim while he was at
Stanford University. Probus clearly demonstrated the power of graphical user interfaces, and the system also incorporated
hyperlinks and early
distributed computing concepts. At HP, Sassenrath was involved with and influenced by a range of HP language projects including
Ada,
Pascal,
Smalltalk,
Lisp,
Forth,
SPL, and a variety of experimental languages.
Amiga In 1982, Carl Sassenrath joined
Amiga Computer, Inc., a small startup company in
Silicon Valley. As
Manager of Operating Systems he was asked to design a new operating system for the
Amiga, an advanced multimedia personal computer system that later became the
Amiga. As a sophisticated computer for its day (Amiga used 28
DMA channels along with multiple
coprocessors), Sassenrath decided to create a
true real-time multitasking operating system within a
microkernel design. This was a novel approach for 1983 when other personal computer operating systems were single tasking such as
MS-DOS (1981) and the
Macintosh (1984). The Amiga multitasking kernel was also one of the first to implement a microkernel OS methodology based on a
real-time message passing (
inter-process communication) core known as
Exec (for executive) with dynamically loaded libraries and devices as optional modules around the core. This design gave the Amiga OS a great extensibility and flexibility within the limited memory capacity of computers in the 1980s. Sassenrath later noted that the design came as a necessity of trying to integrate into
ROM dozens of internal libraries and devices including graphics, sound,
graphical user interface,
floppy disk,
file systems, and others. This dynamic modular method also allowed hundreds of additional modules to be added by external developers over the years. After the rerelease of the Amiga after 3 tries in 1985, Sassenrath left Commodore-Amiga to pursue new programming language design ideas when Amiga went bankrupt in 1994.
Sassenrath Research In 1986, Sassenrath left Silicon Valley for the mountains of Ukiah valley, 2 hours north of San Francisco. From there he founded multimedia technology companies such as Pantaray, American Multimedia, and VideoStream. He also implemented the
Logo programming language for the
Amiga, managed the software OS development for
CDTV, one of the first
CD-ROM TV
set-top boxes, and wrote the OS for Viscorp Ed, one of the first Internet TV set-top boxes.
REBOL Technologies In 1996, after watching the growth and development of programming languages like
Java,
Perl, and
Python, Sassenrath decided to publish his own ideas within the world of computer languages. The result was
REBOL, the
relative expression-based object language. REBOL is intended to be lightweight, and specifically to support efficient
distributed computing. Sassenrath describes REBOL as a balance between the concepts of
context and
symbolism, allowing users to create new relationships between symbols and their meanings. By doing so, he attempts to merge the concepts of
code,
data, and
metadata. Sassenrath considers REBOL experimental because it provides greater control over context than most other programming languages. Words can be used to form different grammars in different contexts (called
dialecting). Sassenrath claims REBOL is the ultimate endpoint for the evolution of
markup language methodologies, such as
XML. In 1998, Sassenrath founded REBOL Technologies, a company he still runs. The company has released several versions of REBOL and produced additional products such as REBOL/View, REBOL/Command, REBOL/SDK, and REBOL/IOS. Sassenrath implemented REBOL V3.0 and released it to
GitHub on December 12, 2012: https://github.com/rebol/r3.
Roku Since 2010, Sassenrath had worked at
Roku, Inc. in product development. He retired in November 2023. ==Personal==