How to test memory in an HP48 RAM card

[Jonathan Busby]

(01-27-2021 07:44 PM)mfleming Wrote:  How about this M-RAM chip from Renesas?
https://www.mouser.com/ProductDetail/Ren...Gi8g%3D%3D

QSPI @ 108 MHz max, single and double data rate, 10^16 write cycles, 20 year data retention, 4/8/16 MB in 8 pin package. About $19 bucks in single qty.

BTW, the typical three score & ten human lifetime is about 2.2e9 seconds, so 100 or 1000 trillion cycles is probably overkill for most applications, especially handheld calculators

Thanks for the tip! That's a really nice chip!

The reason I hadn't considered MRAM is because all the devices I had investigated ( up until now ) either had too high operating currents or had a huge startup current. The one to which you linked has a maximum write current of 30mA, which is quite high on the HP48GX, but, I think it's not a problem.

The chip also can run in QSPI XIP 54MHz DDR mode, which is excellent. Also, the write endurance is even higher than the Cypress Semiconductor chip I was considering which was about 1000 trillion cycle -- this MRAM chip is 10 orders of a magnitude more durable with \(10^{16}\) write cycles!

After more research, I think I may instead go with the MRAM chip to which you linked instead of F-RAM.

Thanks!

Jonathan