HP41CL Secondary MMU Lockup
08-27-2021, 05:56 PM (This post was last modified: 08-27-2021 06:02 PM by Howard Owen.)
Post: #1
 Howard Owen Member Posts: 86 Joined: Dec 2013
HP41CL Secondary MMU Lockup
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

Regards,
Howard
08-27-2021, 06:09 PM
Post: #2
 Sylvain Cote Senior Member Posts: 1,708 Joined: Dec 2013
RE: HP41CL Secondary MMU Lockup
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.
08-27-2021, 06:23 PM
Post: #3
 Howard Owen Member Posts: 86 Joined: Dec 2013
RE: HP41CL Secondary MMU Lockup

(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.

Regards,
Howard
08-27-2021, 07:12 PM
Post: #4
 Sylvain Cote Senior Member Posts: 1,708 Joined: Dec 2013
RE: HP41CL Secondary MMU Lockup
Howard,
I am assuming that no physical modules is plugged at the back.
Have you tried "YFNX" instead of "YFNZ" ?
Sylvain
08-27-2021, 07:41 PM
Post: #5
 Sylvain Cote Senior Member Posts: 1,708 Joined: Dec 2013
RE: HP41CL Secondary MMU Lockup
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
08-27-2021, 08:23 PM
Post: #6
 Howard Owen Member Posts: 86 Joined: Dec 2013
RE: HP41CL Secondary MMU Lockup
(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.

Regards,
Howard
09-05-2021, 05:28 AM
Post: #7
 Geoff Quickfall Senior Member Posts: 771 Joined: Dec 2013
RE: HP41CL Secondary MMU Lockup
And Sylvain strikes again!

Good one.
 « Next Oldest | Next Newest »

User(s) browsing this thread: 1 Guest(s)