HP-48 FRAM Cards

[Chris Dreher]

Short answer
I can't answer about the longevity of FRAM cards that get a lot of reads, but in short I suspect you don't have to worry too much about it.

Long answer
One way to avoid excessive reads and writes to a FRAM card is to not merge it with main memory (i.e. don't use the MERGE or MERG1 commands). You can only merge 128KB or smaller cards on the SX slots 1 and 2 or the GX slot 1. Any card that is 256KB or larger can only go into GX slot 2 which is an unmergable slot.

If you don't merge the FRAM cards, then they just act like a simple storage device (vaguely similar to a USB FLASH drive). As such, they simply don't get read that much by the calculator.

If you do merge the FRAM cards (again, must be 128KB or smaller), they will get read more often compared to an unmerged card since they extend the internal RAM of the calculator. Even then, I wouldn't worry too much about it. The calculator reads the built-in RAM far more often than a merged RAM or FRAM card. A merged FRAM card will be used to store objects in port 0, your home directory, the stack, and maybe the temporary objects when they pile high enough (the pile of temp objects starts out in built-in RAM). However these things are read far less often than the internal structures kept in built-in RAM (ex: the screen buffer is kept in built-in RAM).