HP41CL Secondary MMU Lockup

[Howard Owen]

I dusted off my old 41CL yesterday and was playing around with the secondary MMU settings. I accidentally swapped in an undefined configuration and the calculator locked up. Removing the batteries for a time got me a MEMORY LOST. After that, executing "MMUDIS MMUCLR "YFNZ" PLUG1L MMUEN locks up the calculator again. Have I bricked my expensive tech toy?

P.S. This is v5 hardware. The YFNZ version is 4G

[Sylvain Cote]

I have tried very hard to brick my 41CL and I was not able to do so permanently.

Do another Memory Lost and redo your commands, it should works.
If not, remove the batteries, {wait for ... see period below}, insert the batteries and redo your commands, it should works, if not, use a longer wait period.
Wait period: 1 minute, 1 hours, 1 day, 1 week

Sylvain

PS: On a standard 41C/CV/CX I use a paper clip to short the first and last battery connector in the 41 case, but I do not remember if the trick works on the 41CL.

[Howard Owen]

Thanks for your quick reply!

(08-27-2021 06:09 PM)Sylvain Cote Wrote:  Do another Memory Lost and redo your commands, it should works.

Repeating the steps results in the same outcome. I've tried four or five repetitions, varying the configuration slightly.

(08-27-2021 06:09 PM)Sylvain Cote Wrote:  If not, remove the batteries, {wait for ... see period below}, insert the batteries and redo your commands, it should works, if not, use a longer wait period.
Wait period: 1 minute, 1 hours, 1 day, 1 week

One minute suffices to get me back to MEMORY LOST. I'm currently in the first one hour wait period to see if that improves things.

[Sylvain Cote]

Howard,
I am assuming that no physical modules is plugged at the back.
Have you tried "YFNX" instead of "YFNZ" ?
Sylvain

[Sylvain Cote]

Howard,

Maybe your problem is with the 41CL system RAM at page 0x804.

You can brute force a complete clear of the 41CL with the following:

Code:

MMUDIS          // disable MMU
"801000-0000"   // alternate memory 1 address & reset value
YMCLR           // clear alt-mem-1
"802000-0000"   // alternate memory 2 address & reset value
YMCLR           // clear alt-mem-2
"803000-0000"   // alternate memory 3 address & reset value
YMCLR           // clear alt-mem-3
"804000-0000"   // internal memory & reset value
YMCLR           // clear internal memory
"800000-0000"   // main memory address & reset value
YMCLR           // clear main-mem & creating a memory lost

Sylvain

[Howard Owen]

(08-27-2021 07:12 PM)Sylvain Cote Wrote:  Howard,
I am assuming that no physical modules is plugged at the back.
Have you tried "YFNX" instead of "YFNZ" ?
Sylvain

Oddly enough, loading YFNX seems to have fixed the problem.

[Geoff Quickfall]

And Sylvain strikes again!

Good one.