HP41CX CAT 2 function and MLDL


When testing my MLDL I had no trouble at with my HP41C (speed upgraded). On my HP41CX I could not get my EPROM to show in the CAT 2 listing, and I was getting pretty desperate to find a solution. Then I simply tried one of the functions in the EPROM and .... it worked to my surprise.

Somehow there seems to be a difference between the CAT 2 functioning and recognition of ROMS on the HP41C and 'CX. I know that on the CX only the name of the ROM is displayed, and pressing ENTER will get the function list. In that case I do see the list of my own EPROM.

Anyone knoes the details of the behaviour? Should the ROM name have a certain format?




The CX CAT 2 requires that the module name be at least
eight characters long or else it doesn't display it. This
is why the MATH 1B module doesn't show up on a CX.



It is that simple! Thanks


Sorry, I'm new on the 41,

That means it doesn't work?


All that happens is that the module name doesn't show
up in a CAT 2 without pressing ENTER. When you hit
ENTER during the CAT it allows you to see the individual
programs and functions. At this point they all show up,
including the "missing" one.




I was not aware about this, but I tried a few module names in my HP41CX and I found at least two interesting facts: some of them use a minus sign (-) in the beguining of the ROM name, others use two space characters in sequence as separators, and it may intend to increase the character number: For example:


Regular printer, optical wand and card reader reads (CAT 2):

- WAND 1F -

Two ROM modules with programs:

(these are all the devices I have)

No one of them have less than 8 characters in their names. I own no MATH ROM, so I thank Dalrymple for adding this information. I was not known CAT 2 in the HP42CX would demand it. Was CX's CAT 2 "imported" from CCD?

Meindert, can you still change the MLDL header? If so, I suggest adding (-) signals before and after its existing name...


Luiz C. Vieira - Brazil


This fact is mentioned in Emery's "HP-41 MCODE For
Beginners". I suspect that it's a byproduct of the
rewriting of the CAT function for the CX but haven't
had a chance to burrow through the mainframe listing
to verify this.



The headers are in EPROM, and I have no prgrammer for these. This ROM was made by myself and a friend, and has very limited spare bytes. Tonight I will try another set of EPROMS and check if that works. The ROM I am currectly using has a name of 7 characters (-ML ROM) and that explains it all. The ROM does function in the 'CX, and that is the most important for me.



Don't know if it will be of any help, but I do have an EPROM burner, as well as a huge bunch of 2716 & 2732 chips.

I'll be pleased to modify (names length or whatever) and burn the code you send me, then send the chips back to you into a padded envelope.

E-mail me if you want this *service*, I'll be really glad to contribute.

Cheers from Spain.

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