HP-71B 4Kb (CMT32k FrontPort) Memory Module "Battery" - FRAM

[KimH]

As I prepare a module for FRAM71B to be the Port 1 "Take Over" module I had a thought.

While you open the the 4K Module to build in the OD Switch as described in the FRAM Users Manual P.21, could you have the "Donor" module to be modified to also have a built in "Battery" - doubling the functionality.

This would be neat when you move a small LEX or such from one machine to another

SMD Capacitors offer high capacity Caps with 100uF or more in very small packages.

I would solder a SMD Cap 10-100uF across the Red/Black circles in the attached picture.

BUT (this is the question) how long can the module be "Out" while moving it from one Device to another?

Using Q=I*T with Q=C*V and W=0,5*Q*V hence W=0,5*C*V*V I can't solve for T unless I know I (in uA). And probably some other insights like how the discharge curve look like

I can't seem to find the I for the 4k Memory Modules anywhere, I hope 10uA which would give 15-20 Seconds of time.



Didier, thanks for the help showing the PICT, not a link to the PICT! All it takes is to have dl=0 replaced with RAW=1 at the end of the link

Yes, I know the picture is a ROM, but please humor me...