The Museum of HP Calculators

HP Forum Archive 17

[ Return to Index | Top of Index ]

MLDL2000 Problems
Message #1 Posted by Jeff Davis on 12 Sept 2007, 5:24 p.m.

I have been using my MLDL2000 for Machine Code programming. I have the Zenrom and I am using the MCED program. Recently when trying to add a ROM image to the MLDL2000, I must have placed ill code in the unit now I cannot even take it back to the shipping configuration, I get an invalid Rom name error. I was wondering if someone can assist me with getting the unit back up and running. I hate to keep bothering Meindert with this. Secondly, I would like to hear about some experiences with thier MLDL2000 units that they have received. Please Help, Jeff

      
Re: MLDL2000 Problems
Message #2 Posted by Vieira, Luiz C. (Brazil) on 12 Sept 2007, 10:25 p.m.,
in response to message #1 by Jeff Davis

Hi, Jeff;

I once forgot mine for a while with no use and the RAM contents became garbage. I use rechargeables in my HP41 with MLDL2058, and they went too low. I just connected it to the computer and cleared all RAM contents. If you want to access its contents and clear it through the on-board ROM features (like CLRAM or any other) you'd need to remap the internals anyway, so using the computer is mandatory.

By selecting ROM-based configuration with the dip switches (second switch left-to-right, I guess...), youŽd at least have your HP41 running smoothly. Problem is that even the ROM-based configuration might point to a RAM address with not-friendly contents, and the calculator would crash again.

So, I'd go for the USB approach: run MLDL2K and clear the RAM contents. If you have troubles doing so, let us know.

Hope this helps.

Success!

Luiz (Brazil)

            
Re: MLDL2000 Problems
Message #3 Posted by Meindert Kuipers on 13 Sept 2007, 2:23 a.m.,
in response to message #2 by Vieira, Luiz C. (Brazil)

The best way to handle this is to always have at least one stable configuration (with nothing pointing to SRAM) in FLASH and reserve a dip-switch setting for this. Alternatively the MLDL2000 can be disabled (leftmost switch in lower position) and reprogrammed over USB. From my own experience you have to be prepared for the fact that mcode experimentation is a guarantee for crashes ..

For power management: the standard configuration only charges the SRAM backup capacitor when the HP41 is running or (with the later modification) only when the MLDL2000 is connected to USB. When the MLDL2000 is connected to an HP41 the SRAM is OK as long as the calc has power.

Jeff, I did get your email and will contact you later!

Meindert

      
Re: MLDL2000 Problems
Message #4 Posted by Jeff Davis on 13 Sept 2007, 8:42 p.m.,
in response to message #1 by Jeff Davis

Thanks for your help Meindert and Luiz. Everything is back up and running. I still seem to have problems with what I am assuming is power problems. When the unit is plugged in to the USB everything runs fine and CAT 2 runs as it should. When the unit is unplugged from the USB the unit seems to act like it does not recognize the ROMS. When a CAT 2 is completed it shows jibberish and sometimes locks up. Has anyone else had similar problems? Is this a battery issue? The capacitor backup runs fine and the contents of SRAM are maintained well. Please advise your thoughts.

            
Re: MLDL2000 Problems
Message #5 Posted by Howard Owen on 14 Sept 2007, 12:56 a.m.,
in response to message #4 by Jeff Davis

How old are the N cells in your 41? It certainly sounds like a power issue to me.

I had a similar experience as Luiz had, only my problem came as the result of an old set of N cells. I put the 41/MLDL2K down for a week, and in that time the old cells gave up the ghost and I had to reset the MLDL2K with the USB cable attached and a new set of batteries from Radio Shack in the 41.

Regards,
Howard

Edit: I cain spail reel guud.

Edited: 14 Sept 2007, 12:57 a.m.

            
Maybe...(was: MLDL2000 Problems)
Message #6 Posted by Vieira, Luiz C. (Brazil) on 14 Sept 2007, 6:34 a.m.,
in response to message #4 by Jeff Davis

Hi, Jeff;

Just to make sure I understand: based on your post, should we consider you are connecting the MLDL2000 to the computer through USB when it is not connected to the calculator? If I am not wrong, the unit must be connected to the HP41 when connected to the computer (must check if it is valid for your unit). I've always connected mine to the computer when it is plugged in the HP41, cannot tell what happens otherwise.

Another point: as Meindert mentioned, chances are that the SRAM backup .1F capacitor is not properly connected (broken solder?); this way it would not be possible to hold SRAM contents when it is unplugged.

As a final suggestion, do you have another HP41 for a single test? If port #4 has problems in one calculator, chances are that you have success with another. You see, I myself see no practical solution if testing with another HP41, but after reading about some unknown problems when broken posts are the issue, I believe in anything...

Success!

Luiz (Brazil)

                  
Re: Maybe...(was: MLDL2000 Problems)
Message #7 Posted by Raymond Del Tondo on 14 Sept 2007, 1:33 p.m.,
in response to message #6 by Vieira, Luiz C. (Brazil)

Hi,

> If port #4 has problems in one calculator, chances are that you have success with another.
>
The contact surfaces in port 4 usually suffer from dirt and dust,
sometimes from abrasion,and sometimes from corrosion.
In the first two cases, you could use s.t. like a Q-tip or tissue
to clean the area.
Note that the actual contact surface is _not_ the part you can see
when looking into a port hole. You can only see the isolated part.
The actual contact area is on the sides, as you may imagine
by looking at the modules or card readers contact springs.

HTH

Raymond

BTW: The descr. where to find the contact surface was intended for the unexperienced user only.

Edited: 14 Sept 2007, 7:02 p.m.

                  
Re: Maybe...(was: MLDL2000 Problems)
Message #8 Posted by Jeff Davis on 16 Sept 2007, 11:09 a.m.,
in response to message #6 by Vieira, Luiz C. (Brazil)

"Just to make sure I understand: based on your post, should we consider you are connecting the MLDL2000 to the computer through USB when it is not connected to the calculator?" I always have the calculator connected to the MLDL2K when the unit is connected to the USB. " SRAM backup .1F capacitor is not properly connected (broken solder?);" I do not have any problems with the SRAM maintaining its contents.I have tested for over a week and have had no problems. "do you have another HP41 for a single test?" I have tested with a 41CX halfnut and Fullnut as well as an Early tall key 41C. I have the same problems. I recently cleared the Settings Registers and only put the M2K ROM and the David Assembler in the unit. Everything runs fine. If I load the ZenRom in then the unit goes haywire. There must be something with the ZenRom that conflicts with the MLDL2K. I will be learning the David Assembler instead of the MCED program. Does anyone have a high resolution photo of the David Assembler Keyboard overlay? Thanks for all the help.

                        
Re: Maybe...(was: MLDL2000 Problems)
Message #9 Posted by Meindert Kuipers on 17 Sept 2007, 5:54 a.m.,
in response to message #8 by Jeff Davis

Jeff,

I did some tests myself, while I knew my batteries were almost empty, and I observed the same behavor: SRAM reading can sometimes be troublesome with low batteries (BAT annunciator was on for about one week) and USB disconnected. I cannot explain this yet. So use fresh batteries!

Meindert

                              
Re: Maybe...(was: MLDL2000 Problems)
Message #10 Posted by Meindert Kuipers on 18 Sept 2007, 11:58 a.m.,
in response to message #9 by Meindert Kuipers

Jeff (and other MLDL users),

I have done some further testing, and currently I suspect a problem with M2kM. I am seeing problems like Jeff has seen with different behavior with USB connected or disconnected. The issue is that is could be a combination of M2kM with firmware (I am playing with a new firmware version as well), USB should normally have nothing to do with firmware, except when the M2kM software controls a pin and leaves it in a state that I did not expect it to.

Will do some more testing and let you all know the outcome ...

Meindert

                                    
Re: Maybe...(was: MLDL2000 Problems)
Message #11 Posted by Jeff Davis on 18 Sept 2007, 7:38 p.m.,
in response to message #10 by Meindert Kuipers

Meindert, Thanks for posting this information. I look forward to hearing your thoughts and conclusions. Thanks for all your Help.

                        
Re: Maybe...(was: MLDL2000 Problems)
Message #12 Posted by Vieira, Luiz C. (Brazil) on 17 Sept 2007, 6:26 a.m.,
in response to message #8 by Jeff Davis

Hi, Jeff;

Quote:
I recently cleared the Settings Registers and only put the M2K ROM and the David Assembler in the unit. Everything runs fine. If I load the ZenRom in then the unit goes haywire.
Again, sorry to ask questions that may lead to no conclusion. Some ROM modules show unexpected behavior when connected with others, surely the ones that deal with inner O.S. operations and specific reaction to keys (key cature). So far I found no ROM image that works fine with the FORTH ROM, and the calculators I tested work fine with the FORTH ROM alone.

This is just to ask if you tested the ZenRom alone or with the M2K ROM. You see, the [ON][ENTER] feature in the M2K ROM implies ROM intervention in the O.S. regular ON sequence (it doesnŽt even work with the halfnut units). I'd guess this is probably one of the reasons of the calculator behavior.

Best regards.

Luiz (Brazil)

                              
Re: Maybe...(was: MLDL2000 Problems)
Message #13 Posted by Jeff Davis on 18 Sept 2007, 7:36 p.m.,
in response to message #12 by Vieira, Luiz C. (Brazil)

I have now tried to use just the ZenRom and also load the M2K0000Rom to use as my 4K page for writing machine code. I still have problems with the ZenRom. Once a MCODE routine is run the system will never work corectly again. I load the David Assembler with Main Frame Labels and the same M2K0000 Rom and with the same MCODE routine everything works fine. The only issue that I have had is the Calc will pop out of ASSM mode when SST or BST pushed and only intermittent. This problem is documented in the David Assembler Manual. So, I think that the ZenRom at least on my MLDL2078 will not function consistently. The David Assembler seems to be much more stable. Does anyone have a High Resolution Pic of the Keyboard Overlay? I tried to use the one (on the other site) but when I finally get it to the correct size, it is very difficult to read.

                                    
Re: Maybe...(was: MLDL2000 Problems)
Message #14 Posted by Meindert Kuipers on 19 Sept 2007, 3:25 a.m.,
in response to message #13 by Jeff Davis

Jeff,

I will do a scan of my keyboard overlay for the David Assembler. I have never used ZenRom myself, but I will give it a try in the MLDL2000. Maybe you should try ZenRom just by itself, without M2K ROM loaded. The entry points may not be programmed very well, at least put the ZenRom in a port lower than M2K ROM.

I have no results yet for the firmware upgrade and USB issue. Maybe this evening I have time for that.

Meindert

[ Return to Index | Top of Index ]

Go back to the main exhibit hall