|The challenge: Improve the features
and performance of this MIDI percussion controller.
The solution: Assume development
of both the operating software and the analog hardware of this product.
To improve the dynamic response of piezoelectric sensors, T-Recursive designed
and laid out a "quasi-logarithmic" pulse amplifier, and greatly optimized
the supporting software. To simplify the addition of new features,
we developed a "menu engine" allowing the user interface to be changed
and expanded in hours rather than days, and adapted the code to use paged
memory, doubling the available memory space. New features added by
T-Recursive include: more flexible and varied event processing; MIDI input
processing, sequence playback, and bulk dump; absolute and variable time
|The challenge: Develop an object-oriented
application-specific language for a distributed industrial control system.
The solution: Specify and implement
the ANGL language using the SwiftX Forth cross-compiler. Given a
general capabilities description, T-Recursive specified, designed, implemented,
and documented a late-binding object-oriented extension to SwiftX Forth.
We also implemented a multi-drop master-slave RS-485 network to the client's
specification, including PC and modem gateways for remote access.
This system was designed to be compatible with the BACnet(tm) object model
and message syntax. Application software developed by T-Recursive
included predefined classes for event processing, and tokenized formula
|The challenge: Improve the capacity,
and lower the cost, of this Zilog Super8 processor board, while retaining
compatibility with old code.
The solution: Specify, design,
and lay out a new "D5" processor board to fully exploit the Zilog Super8.
The new board uses split instruction/data spaces and paged memory to quadruple
the on-board memory and allow off-board expansion. A new, expandable
32xN analog matrix replaces the previous 12x24 matrix, while retaining
full compatibility with old connectors. Surface-mount devices and
tight layout replaced the expensive octagonal board with an economical
-- and 40% smaller -- rectangular board, and the redesign allows the D5
board to be depopulated for simpler applications. T-Recursive converted
old software to run on either board, using a few "personality" files.
|The challenge: Support the development
of the Open Terminal Architecture for point-of-sale terminals.
The solution: Develop kernel
software for a variety of point-of-sale terminals. As a software
subcontractor, T-Recursive maintained and supported kernels for 8051, 6303,
and 68000-based terminals. We researched and implemented fast and
compact extended-precision math algorithms which have since been widely
adopted for the OTA security routines. We also implemented a byte-coded
kernel for an 8051-based "smart card" which runs twelve times faster than
a competing product, using less than 128 bytes of RAM and 3.5K of ROM.
|The challenge: Automate the operation
of this manually controlled, "seat of the pants," 1960s-vintage particle
The solution: Design and construct
a real-time, distributed, inference-driven control system using "off-the-shelf"
hardware whenever possible. New Micros single-board computers and interfaces
were specified. For the highly-specialized connections to the accelerator
itself, T-Recursive designed, laid out, and assembled "fail-safe" circuit
boards for retrofit into the control console. T-Recursive developed all
software, including a distributed, embedded, real-time expert system to
perform the heuristic decisions of a human operator. To meet the networking
requirements of the accelerator lab, we developed a novel token-ring local-area
network using standard serial ports. MPE Forth, F-PC Forth, and assembly
language were extensively used.
|The challenge: Create an inexpensive
platform to study tightly- and loosely-coupled multiprocessor architecture.
The solution: Design a shared-bus
microprocessor board using an inexpensive 8-bit processor. T-Recursive
designed this board using the Motorola 6809 with custom bus arbitration
and memory mapping logic, plus multiple high-speed serial links and additional
I/O. We also laid out and produced a small number of printed-circuit boards
for sale to educators and experimenters. Cost of fully-configured prototypes
was under $200 per CPU, well under the goal of $1000 for a four-processor
The challenge: Create a lighting control system which can compete on price with the other manufacturer's low-end memory consoles, and on features with their high-end memory consoles.
The solution: Specify and design
a scalable multiprocessor lighting control system. From three to ten Zilog
Super8 processors can be installed, making a range of consoles possible
with identical features and software. The maximum configuration, LD1000,
controls 4000 dimmers on 1000 channels, making it (at its introduction)
the third most powerful console on the market. T-Recursive conceived, specified,
and designed the system, and designed all hardware, including video, disk,
and multiplex I/O, and a proprietary interprocessor bus. We prototyped
and laid out the key "channel processor" board. We designed the multiprocessor,
multitasksing software architecture, wrote a high-performance multitasking
kernel, and wrote the executive control and operator interface software
in Forth. Our assembly-language computation software uses novel calculation
techniques to achieve a 300% improvement in processing speed. We developed
the hardware and software for the proprietary local-area-network, which
allows distributed control from up to 30 control stations, and supports
fully redundant backup. T-Recursive worked with client staff and another
contractor to deliver, in 1.5 man-years, a product whose equivalent took
a competitor 5 man-years.
|The challenge: Lower the cost and
increase the capacity and capabilities of the Teatronics Producer II lighting
control console, while adding support for the new DMX-512 protocol. Furthermore,
the design must accomodate Teatronics' envisioned Quantum high-performance
The solution: Replace the existing
STD-bus Z80 processor and I/O cards with a custom single-board computer
using the Zilog Super8. The new board runs faster and has more memory,
increasing the console capacity, at lower cost. While retrofitting to existing
hardware, it adds new interfaces for DMX-512 output, floppy disk, IBM-compatible
printer, serial remote control, VFD/LCD display, and IBM video display
card. T-Recursive designed, laid out, and prototyped the board, and wrote
all I/O drivers. We developed a Z80-to-Super8 translation program to quickly
migrate the existing Z80 software to the new board. Later, T-Recursive
developed assembly-language software to add remote control, video display,
printer, and disk functions to the Producer II+. The Super8 board was used
"as is" for the Quantum console, at a substantial cost savings; T-Recursive
also assisted with software development for that system.
|The challenge: Replace the analog
control electronics of the Genesis dimmer pack with a controller capable
of handling the new digital protocols DMX-512 and D192. The new board must
retrofit into existing dimmers. Furthermore, the design must be expandable
to 96 dimmers for the new MD288 dimmer rack.
The solution: Design a controller
using the Zilog Super8 microprocessor to receive USITT DMX-512, USITT AMX-192,
Colortran D192, and 10-volt analog control signals. The proprietary hardware
and software design allows the processor to generate Triac firing signals
directly with no external timers, lowering cost, and allowing the board
to exactly match the form factor of the old analog controller. It accomodates
up to 24 dimmers on three phases for dimmer packs, or up to 96 dimmers
on one phase for the MD288 rack. The hardware was designed and prototyped,
assembly-language software was developed, and diagnostics and documentation
were written, in just two months.
|CamelForth, a highly-portable ANSI standard Forth compiler/interpreter, for "in-house" embedded projects. It has been implemented for the Intel 8051, Zilog Z80, and Motorola 6809.|
Page updated 12 Mar 2000