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Ken Shirriff

Here's a closeup of the part number and Ramtron logo on the die.

Microscopic text on the die: FM24C64A Ramtron.
23 September at 19:03 | Open on oldbytes.space
5 comments
Ken Shirriff

To learn more about this FRAM chip, see my blog post: righto.com/2024/09/ramtron-fer
Thanks to CurousMarc for supplying the chip.

23 September at 19:04 | Open on oldbytes.space
bitsavers.org

@kenshirriff

why do they have finite r/w lifetimes?

23 September at 19:23 | Open on oldbytes.space
Ken Shirriff

@bitsavers There are multiple factors that limit the number of writes that FRAMs can handle: changes in crystal structure as Ti ions replace O, mobile ions collecting at grain boundaries, and something to do with 90º domains.

23 September at 19:41 | Open on oldbytes.space
F4GRX Sébastien

@kenshirriff @bitsavers it's not really infinite since the endurance was probably reached in Marc's DRO. The fram was used by the readout to give the illusion of an absolute scale, but I believe the integrated fram that failed was updated too often (maybe every scale tick).

23 September at 19:53 | Open on chaos.social
gudenau

@kenshirriff Oh it's almost like microscopic core memory? Pretty neat stuff.

23 September at 19:40 | Open on fosstodon.org
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