106 bytes used of 128 leaves some possible spare for 128kb kam hardware.Hardware Manual wrote: ^ Electronics Division PECE DepartmentINTRODUCTION TABLE 1-4. REFERENCE PUBLICATIONS
*Functional and Electrical Specification for a 128-Byte Custom Keep-Alive Read/Write Memory (KAM) ES-N7700010FBCADA
* Functional and Electrical Engineering Specification for a 2K-Byte Keep-Alive RAM with parallel I/O (RAM1/0) ES-N7500030FSCAGA
*Functional and Electrical Engineering Specification for a 2K-Byte Keep-Alive RAM with Serial and Parallel I/O (RAM/CART) ES-N7500120FSCAGA
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MEMORY (on-board 81C61, 81C62, 81C65, & 81C66)
The 81061, 81062, 81065, and 81066 all have the same memory size and type, and memory addressing circuits. Memory on-board these devices consists of 2,048 bytes of read/write static RAM. This RAM was specifically designed to provide keep-alive storage for user data in battery powered systems. The RAM can store data while consuming less than 100 microamps of current under a wide input voltage operating range (+2.0 VDO to +5.5 VDO) when non-active. The 81065 and the 81066 provide a special keep-alive power input for their RAM.
Later chips apparently keep RAM alive as well according to the above snips.