The Standard 28C64 Circuit Induces a Noisy End
An inquiry suggests it is past time to report that after four years of observing apparently random failures of Unimprinted Electrical Devices (UEDs) and Intention-Imprinted Electrical Devices (IIEDs) in 2010 this lab indeed discerned why all conventional Ally-type designs eventually become inert.
Surveying the Atmel data sheet, one reads that a Software Data Protection (SDP) lock is invokable via a specific code sequence that makes the memory unchangeable. As an early-generation device, this mechanism was useful if not necessary to prevent data corruption during power-on/off cycles.
This problem I have patiently observed over several years with concern and caution, of time and again seeing these cells die (meaning they objectively test as a FAILED device), is explained by the SDP sequence being triggered by noise. When this happens, the cell’s sensitive CMOS transistors can no longer adapt to intentional nor environmental conditioning.
Unfortunately, it becomes statistically inevitable that all conventional Ally-type designs ever offered will eventually become latched and unresponsive due to noise triggering the SDP lock. That is why I have recalled the SC30/PS30 and its variants from general sales.
To really know what is going on, you must regularly monitor these chips with an EEPROM reader, or work closely with us to periodically ensure that your cells are still electronically ‘alive.’ Any lesser practice is seriously uninformed; guaranteeing that the device without indication decays into a rock-like placebo.
Following our conservative, methodical, finely-researched course regardless of any impact on sales is how we maintain our bearing: Credibility pursuing Incredibility.