New Rock-afire Explosion Control System

The New Rock-afire Explosion Control System is a control system designed by Creative Engineering Inc. in the early 1990s as the standard control system for use with the New Rock-afire Explosion. It is significantly more technologically advanced than previous Creative Engineering control systems and was designed fully in-house, in contrast to prior systems such as the one used for the original Rock-afire Explosion.

As the hardware and software comprising this system has been unavailable for analysis by knowledgeable persons, some of the information on this page is incomplete or of a speculative nature.

Overall system architecture
The New Rock-afire Explosion Control System is designed around an Apple IIe computer with several custom cards. Audio, video, and data storage for the show is through one or two (depending on show type) VCRs and a 3.5" floppy disk. The Apple computer manages scheduling of show segments, and outputs data to various pieces of external hardware to allow controlling the animatronic characters, stage turntables, props, and other miscellaneous show systems. The Apple's standard display output is used for administrative functions in conjunction with a lightpen, while show selector and manager panels control the day-to-day operation.

Apple IIe cards
Listed in order from left to right from the front of the computer


 * 1) Decoder - Accepts video input from the VCRs, decodes the control data from the VBI, and provides a switched video output to the Turntable Board to feed the TVs. Custom designed by CEI.
 * 2) Showplay - Outputs two channels of Pianocorder-format data to drive the character Bit Strippers, and miscellaneous signals to control the Turntable Board. Custom designed by CEI.
 * 3) DOC (acronym unknown) - Implements the "SCI" serial interface used to communicate with the show selector and manager panels.
 * 4) RS-232 - RS-232 interface for controlling the main VCR. Unknown if custom or COTS.
 * 5) Floppy controller - Interfaces with the 3.5" floppy disk drive. Custom designed by CEI.
 * 6) (Empty slot)
 * 7) Lightpen - Reads lightpen signals to control the computer. Custom designed by CEI.

Turntable Board
Also known as the Big Important Board, the Turntable Board handles many more show functions than its name implies. It is comprised of four 6801 microcontrollers and various analog and digital circuitry.


 * Reads position inputs from the center turntable, and controls its air valve
 * Switches the audio to the amplifiers from the two VCR sources
 * Buffers the video signal feeding the TVs
 * Acts as a passthrough for show data, leading to additional external bit strippers
 * Sends remote control signals to the Thank You VCR
 * Controls the strobe light

27 Bit Strippers
The 27 Bit Strippers in the system accept Pianocorder-format data as input. A 6801 microcontroller decodes the data and controls open-drain outputs for character valves, while a 6805 microcontroller (68705, UVEPROM programmable variant) generates standard "analog" control signals for servos. These boards can decode a a total of 27 bits, hence their name. Twenty-one of these bits can control valves, with the remaining six being used for position selection for the servos. There is support for three servos, usually eyes left/right, eyes up/down, and eyelids wide/closed. Each servo has two bits dedicated to it, with each bit being dedicated to one of the two "away" positions. With neither bit activated, the movement returns to its "home" position.

TODO: Is the 74'07 buffering the data for passthrough?

Video Decoder
TODO: Data presumed to be in the VBI. Is the actual character movement data in the VBI or is it stored on the floppy and the VBI just has a timestamp or similar?

SCI Interface
TODO: Basically everything. We know it works in a loop... what is the actual protocol?