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This document establishes a public, timestamped priority record for a set of original technical discoveries and inventions relating to the Casio FX-9750 and FX-9860 series graphing calculator serial interface. These discoveries and inventions were made independently by the author beginning in 2008 with the most recent invention completed in 2025. Throughout this document, the term discovery is used where the contribution identifies a previously undocumented property of an existing system; the term invention is used where the contribution creates a new method, scheme, or application that did not previously exist. Two discoveries are documented. First, the READY-gated timing tolerance: the discovery that the Casio RECEIVE() protocol has two locations at which the calculator waits for extended periods without issuing a COM error. These windows of opportunity in the handshaking protocol are designated W1 and W2. At these locations, a wait time that is at least 3000 times greater than previously documented in community literature is possible, with a validated maximum of 50 minutes. Second, READY-window interval logging: a technique exploiting this tolerance to achieve consistent autonomous time-interval data logging at any interval from 2 seconds to 300 seconds. This is validated across four microcontroller platforms and FX-9750 series models including legacy and current GIII series. There are seven inventions documented. One invention is documented in external behaviour only, with full technical details withheld pending peer-reviewed publication: Mantissa Frame Encoding (MFE), a novel encoding scheme that transmits synchronous readings from multiple sensors to the calculator in a single RECEIVE() call, recovered by a universal Casio BASIC decoder requiring only arithmetic operations available on all supported models. Two standard configurations have been validated: up to three sensors at 12-bit resolution and up to four sensors at 8-bit resolution, each with a structured application field supporting status reporting and alarm management. Zero transmission errors have been observed across all four validated microcontroller platforms. Together these discoveries and inventions support four validated operational modes; all of these are inventions. Mode 1 (remote control) uses the calculator keypad to transmit user-generated values to a connected microcontroller for execution, demonstrated in the Casi robot project. Mode 2 (multi-sensor display terminal) uses MFE-encoded READY-window synchronous sampling to display real-time sensor readings with live graphing and statistical analysis. Mode 3 (human-machine interface with alarm management) extends Mode 2 using the MFE structured application field for fault monitoring and system status reporting. Mode 4 (secure input device) uses the calculator's tamper-evident physical keypad to transmit user-entered discrete values to a microcontroller; an application with no prior equivalent via the Casio serial interface. Combined Mode 1 and Mode 2 operation is claimed as a further original invention: a closed-loop measurement and control system in which the calculator simultaneously serves as display terminal and control input device. This is identified as the intended basis for the first New Zealand secondary school Industrial Measurement and Control course. No prior secondary school IMC course using a calculator-based or equivalent low-cost system has been identified in New Zealand or internationally. A user-triggered field survey logger combining MFE-encoded automatic sensor acquisition with microcontroller-maintained elapsed-time recording and user-entered categorical observation is described as a further original invention. A prior art statement documents a comprehensive search of community forums, GitHub repositories, and academic databases. The most technically sophisticated prior work identified, MiniExperimenter (shabaz123, 2020), operates via the EA-200 hardware protocol at a different baud rate, does not solve the interval timing problem, and does not achieve synchronous multi-sensor encoding within a single transmission. It does not anticipate any claim made in this disclosure. Open-source code for single-sensor READY-window interval logging is published at github.com/MikeFentonNZ/Casio-calculator-picaxe-esp-datalogger-upgrade under CC BY-NC-SA 4.0. The encoding invention details are withheld from all licences pending peer-reviewed publication.