HP71B News??


Have been off this great forum for a few years... interested in discussing high-powered 41s and 71bs.

Any new stuff on the 71?

BTW, I just started a 71B Facebook page if anyone is interested.


If you're not familiar with the SY-41CL, make sure and check out:

Systemyde SY41CL page

Welcome back!


Edited: 4 May 2012, 4:12 p.m.



That is cool but I am not a tech guy. Is this a calc? What does it look like? What does it do? Cool website.


Hi John

As I understand it replaces the main CPU board of the HP41 with one with a CPU that can run up to 50 times faster, has additional memory available along with appropriate memory management facilities and, best part of all as far as I am concerned, has the images of 120 or so plug in modules, HEPAX, ZENROM, PPC, etc. built in! Have a look at the list on pages 20 to 25 of the 41CL Manual on the Systemyde site.
The board also has a RS-232C serial port.

When installed in a C or CV it provides all the functions of the CX apart from the Timer functions for which a Time module is required.




The 41CL is a replacement pcb for the CPU board in an HP-41.

You only have to open an HP-41, take out the original CPU board,

and replace it with the 41CL board.

You'll instantly get a super fast HP-41 with lots of memory:-)




Guys! Cool, so a novice can self install this thing?

VERY COOL. Back in 1985 I modified my 41CV with the capacitor change that doubled speed.

How do you buy this board? What about cosmetic changes to the 41? Like AMG Mercedes you should rework the case to reflect the fact that you have a lot more under the hood... as it were. I'm quite serious about this.




Prices are here and that page has a link to the order form which you can download, complete, and then scan and email Monte Dalrymple at the email address given.






On the subject of speed, if 50X faster that would make the 41CL faster than the HP71B, which is not possible, or desirable. People graduate to the 71B.



The board comes with a replacement front label for the calculator.
The board cannot be used with a halfnut, so make sure you have
the right kind of donor calculator. The installation instructions
are covered in the manual, available on the website.


Great, how do I order? Can it be done securely on the website? Are there pics of a converted 41?



Photo of my 41CL

41CL order form

Sorry, no secure ordering on the website. You need to download the order form, fill it out and return it. Then I send an invoice with the amount and payment instructions (PayPal).


BTW I did my calc mods at Berkeley. B.S. 1987, M.B.A. 1993. So, Monty , we have the two CAL degrees in common, FYI.


Cool. Not many of us around.


In addition to skimming the manual, you might want to check out some of the videos that Geoff posted to YouTube about the 41CL, particularly his HHC 2011 presentation. Just search there for "HP41CL".


Edited: 5 May 2012, 7:53 a.m.


Is this a calc? What does it look like? What does it do?

It´s the best thing that ever happened to the 41 system (HP-IL notwithstanding)


Angel, say hello to Jim R. for me.


Check out this earlier link for the correct choice of donor HP 41c.

41c donor shells for CL upgrade


Hi Geoff! I ask you please to confirm my reading of your tutorial, in matter of a 10nF cap to insert....it needs only if I find in my donor 41C squared display drivers, isn't it?

OT: where are you now, flying somewhere?

Cheers from Italy

Edited: 7 May 2012, 2:39 p.m.


In London,

Tomorrow London meeting of HPCC, yahoo,

You are correct, only attractive square encapsulated drivers require the cap.

Have fun


Thank-you Geoff for the replay, going soon to make the trasformation and I hope to be not like doc. Frankestein!

Let me know please if there will be any reportage from the meeting (youtube I mean). I wish you and the other members of this forum, who will join to the meeting tho enjoy this weekend.
Buon lavoro!


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