41CL MMU Backup

[Monte Dalrymple]

(05-28-2020 10:15 PM)twoweims Wrote:  What is the proper way to backup and restore the MMU Configuration (Page 804)
to / from Flash Memory.

If I write YFWR page 804 to page 3F1 I can see that the CRC of page 3F1 is getting changed. The 41CL Manual seems to be silent on the procedure for restoring page 804. I tried MMUDIS, MMUCLR, then YMCPY with 3F1>804 in ALPHA. When I enable MMU the calculator locks up with a constant tone until I remove the batteries.

I am obviously missing some important step.
I would appreciate any advice on this and also to learn some backup strategies/best practices from fellow CL users.

Was the Flash at 0x3f1 empty before you wrote to it? What was the configuration you had previously stored at 0x3f1? There are locations in Page 804 that are used for internal stuff by YFNX and YUPS, and you are actually executing code transiently stored in this area when doing Flash operations. But that shouldn't matter when doing YMCPY. I'll try to duplicate what you are doing in the next couple of days and let you know.