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hth · 07-31-2016, 01:44 AM

I got an MLDL2000 way back, but never got around to use it, until now.

It started out quite nice. I am testing some software I develop, but after a while I ran into trouble in that from time to time the whole machine goes totally unreliable. As I am fiddling with poll vectors and the key sequence parser, I thought my code was the problem, but after turning off these vectors, it is still not reliable.

It can work for a while, then it just decides that it do random crazy things with my key presses and sometimes scroll the LCD sideways a bit.

Looking at the MLDL2000 pages, I noticed that some few devices had a bug described as "In some cases the MLDL2000 may become unstable, especially after key presses.", which sounded spot on to me.

Fixed in a 1.51 firmware, I was running 1.00, so it was time to upgrade. I upgraded to 1.70 and everything seemed fine on the PC side, I could upload images and configuration.

On the HP41 side, nothing worked, it does not even want to wake up when the MLDL2000 is enabled, either using flash or SRAM configuration. Nothing, it is totally dead. If I disable the MLDL2000 using the DIP switches, I can get the HP41 to wake up, after some backarrow-ON presses.

I tried the SRAM self test and it worked fine.

Is there something else I should do to get it to work? I take the same steps as before, it looked good when flashing firmware, it reads back version number properly.

Håkan

Ángel Martin · 07-31-2016, 05:18 PM

It's been a while since I used my MLDL_2k (the CL is so much easier and powerful...) but in some instances it also did a bit of acting up, specially with configurations in the settings registers that were a little challenging - say HEPAX, Library#4, etc/

I usually managed to bring it back to order using very simple configurations, and building them incrementally. Also it's important you have the right stuff in RAM/Flash and not pointing to "unknown" blocks...

hth · 07-31-2016, 07:14 PM

(07-31-2016 05:18 PM)Ángel Martin Wrote: It's been a while since I used my MLDL_2k (the CL is so much easier and powerful...) but in some instances it also did a bit of acting up, specially with configurations in the settings registers that were a little challenging - say HEPAX, Library#4, etc/

I usually managed to bring it back to order using very simple configurations, and building them incrementally. Also it's important you have the right stuff in RAM/Flash and not pointing to "unknown" blocks...

Thanks! I have stripped it down to single block configurations, one OS flash image for flash settings 0 and a single SRAM block for the SRAM settings 0. It seems hard to get it "wrong" in simple setups, I can image more elaborate configurations may require some care.

The HP41 does not want to work with it anymore. It looks fine on the PC MLDL manager side. I contacted its maker, but he is on vacation, so it will have to wait. Not a big issue, there are plenty of other things to do in the mean time.

I found the MLDL2000 very easy to use, a few clicks around to download over USB. It provides very quick turn arounds for testing.

My CL is not as easy to use as it lacks a serial port, I should perhaps get one at some point. It did freeze up the other day, and I had to remove batteries to get attention from it. I have to see if that was just a single glitch, time will tell.

**rprosperi** · 07-31-2016, 08:24 PM

(07-31-2016 07:14 PM)hth Wrote: My CL is not as easy to use as it lacks a serial port, I should perhaps get one at some point.

41CL Serial Port is cheap but highly recommended! Uploading and downloading is very fast, simple and trouble free.

hth · 08-11-2016, 12:26 AM

Just to follow up on this.

I got a reply from its maker and it did the trick. After erasing the contents of the MLDL2000 and then putting back everything again (it was not that many things in my case), it works again!

Even better, the problem I suffered from with the unreliable erratic behavior is gone, everything works as it should.

Ángel Martin · 08-11-2016, 04:35 AM

(08-11-2016 12:26 AM)hth Wrote: I got a reply from its maker and it did the trick. After erasing the contents of the MLDL2000 and then putting back everything again (it was not that many things in my case), it works again!

Good to hear your unit is back in shape. I hope that only applied to the sRAM contents, and not to the FLASH?

hth · 08-11-2016, 04:55 AM

(08-11-2016 04:35 AM)Ángel Martin Wrote: Good to hear your unit is back in shape. I hope that only applied to the sRAM contents, and not to the FLASH?

I had to erase both SRAM and FLASH. I only had the MLDL operating system module in the FLASH, so it was just one module page to restore. I did not bother to set up a FLASH configuration yet, I just use an SRAM configuration with both RAM and FLASH images.

The MLDL2000 is a truly useful device and very simple to use. For testing and playing around with modules on hardware, it just does not get much easier than this.

Ángel Martin · 08-11-2016, 06:30 AM

(08-11-2016 04:55 AM)hth Wrote:
(08-11-2016 04:35 AM)Ángel Martin Wrote: Good to hear your unit is back in shape. I hope that only applied to the sRAM contents, and not to the FLASH?

I had to erase both SRAM and FLASH. I only had the MLDL operating system module in the FLASH, so it was just one module page to restore. I did not bother to set up a FLASH configuration yet, I just use an SRAM configuration with both RAM and FLASH images.

I'm a bit rusty but I don't remember anything about an MLDL operating system module - I sure don't have such a thing on my unit... ?

(08-11-2016 04:55 AM)hth Wrote: The MLDL2000 is a truly useful device and very simple to use. For testing and playing around with modules on hardware, it just does not get much easier than this.

Agree - and I sure love seeing that USB cable connected to the 41/MLDL2k combo.

hth · 08-11-2016, 06:52 AM

(08-11-2016 06:30 AM)Ángel Martin Wrote: I'm a bit rusty but I don't remember anything about an MLDL operating system module - I sure don't have such a thing on my unit... ?

Mine came with one -MK2 ROM flashed into it. You can find it as a .rom file at http://hp41.kuiprs.nl/m2k_rom.rom

I restored it after erasing the flash.

Thinking about MLDL OS, I think everyone came with something like that. For my home built MLDL from around 1983 I stirred together one myself, mostly based on things found in various PPC journals, perhaps with some home brewed stuff as well. I do not remember as I have not looked at it for a long time. I considered dusting off that MLDL, but getting images from the computer into that one would be a lot tricker compared to the MLDL2000.

Back then, I used the parallel port on a Commodore 64, simulating the HP41 bus signals as fast as it could to download the fresh image into MLDL RAM, I think it took 35 seconds. Haha, and it was nothing compared to the poor Commodore 64 building modules, pulling the source in from 3 files from that super slow floppy drive it had. It just could not fit all the source code into memory all at once. The assembler was pretty fast though, as it was written in 6502 machine code, but that floppy drive took its time...