SYSTEM AND METHOD FOR STORING FIRMWARE IN A HUMAN-IMPLANTABLE MEDICAL TREATMENT DEVICE

In a medical treatment device implanted within the body of a patient, a system and method for organizing storage of the device's firmware in ROM, RAM, and EEPROM such that a ROM-based system is implemented initially using pointers stored in RAM, which RAM-based pointers point to ROM-based functions. When revisions to the functionality of the treatment device are desired, code is downlinked via an external programmer and telemetry to link to RAM, and one or more pointers, as appropriate, which pointers point to the downlinked code in RAM, are downlinked to RAM. In this manner, revisions to the firmware of an implanted medical treatment device can be downlinked to the device thereby eliminating the need to explant the device in certain circumstances. The amount of code placed in ROM is maximized, with only pointers to functions and new or revised code segments stored in RAM as needed.