HP-41 Quiz: How to pack 100k in ROM? (on-line)


Here's a short quiz for fellow HP-41 fans:

Q: which configuration(s) of modules do you know that when put together you have a max'd out system, with a total of 100k in ROM space? - that is from page 0 up to page F; 16 pages in total including of course the native OS.

Must be on-line, and it doesn't require a CL (also possible w/ Clonix/NovRAM, and MLDL2k).

Hint: think Bank-switching... and Library#4.

My answer (and my current configuration on the CL) in a couple of days, let the games begin!

Edited: 2 Sept 2012, 4:33 a.m.


Did I mention that my CY has a usable "ROM" space of 96k with HP-IL module installed, and 112k with my CY-INIT instead of the HP-IL module?




Well, no; now that you mention I don't think you did before. Would you care elaborate and tell us the port mapping for such a feat?

And while you do, remember that one of the conditions was that they're "on-line" :-)


Hi Ángel,

Not sure if this applies since it uses the RAM switch command from Geir's ICEBOX.

- CX 12K Mainframe OS + 12K EXT Fun & TIMER (pages 0 - 5)

- IR Printer 8K (page 6)

- HEPAX 16K (page 7)

- 64K RAM NoV-64 (pages 8 - F)

One RAM page must contain ICE-Box to allow on-line RAM block swapping.

Total: ROM addressable space 112K



PS: Yeah, I know it's easier using LIBRARY#4... just wanted to offer another approach... ;-)

Edited: 2 Sept 2012, 8:35 a.m.


I should have used an HP calc before posting;-)

The correct amount is 100k of course.

12k CX ROM

24k CY-INIT (6 ROMs on 2 pages (6,7) in 3 banks)

64k CY RAM Box

No HP-IL module plugged.

The CY-INIT ROMs are "online" insofar that during the interactive CY configuration, the user can choose to install each of the available ROM images, including those in the hidden banks.

With a NoVRAM I could have pushed it to 112k, as Diego showed;-)

Edited: 2 Sept 2012, 10:08 a.m.


Ah but all that is including RAM - and the idea was ROM only, or should I say ROM-capable RAM (quasi-RAM, HEPAX RAM) included but X-MEM not so, sorry Diego :-)

Besides not sure about those CY-INIT ROMs - are they switchable back and forth at any moment, as though they were banks of a bigger module? Or in other words, say you want to run a program including functions from two (or more) of these, can it be done?


Hi again,

Well, I've not included the EXT Memory, just the 12K ROM in the CX which holds the EXT Functions and the Timer.

Two X-MEM modules (or a Double X-MEM) could be added to my previous arrangement since two I/O ports will still remain free... :-)

Look forward to reading your own arrangement.

All thge best from Canary Islands.


Edited: 2 Sept 2012, 6:10 p.m. after one or more responses were posted


My mistake Diego, you´re of course right!

FWIW, here´s the configuration that prompted the thread, which if anything just demonstrates the versatility and uncanny resilience of this 30+ years old design.

12k - Pages 0,1,2 - 41 OS

12k - Pages 3, 5, 5-bank2 - CX OS

4k - Page 4 - Library #4

8k - Page 6, 6-b2 - IR Printer

16k - Page 7, b2, b3, b4 - Power-CL

16k - Page 8, b2, b3, b4 - Hepax

12k - Pages A,A-b2, B - Advantage

20k - Anythng else you wish on pages 9,C,D,E, and F


100k, on-line, all accessible and ready to go.

Long live the HP-41!

Best wishes,

Edited: 2 Sept 2012, 4:05 p.m.


Yes... that's a nice one, and that remembers me that I still owe you... (all Clonix/NoV users in the end) the required upgrade to allow banks 3 & 4 configuration.

Shame on me, but I don't forget it, just too many issues in the last two months.




Correction of the correction;-)

The correct amount is 112k of course.

12k OS Base

12k CX ROM (dunno why I ommitted them in the 2nd post)

24k CY-INIT (6 ROMs on 2 pages (6,7) in 3 banks)

64k CY RAM Box

The CY-INIT ROMs are not "online" in the same way as AMs L4 solution, but "online" for the intended task: Restoration of the RAM box with some options.


Hola, Ángel; ¿que tal?

I am counting the remaining minutes - about 100,000 - for I grab the two 41CL boards (three, considering the one actually addressed to a friend) prior to go delving into these experiments...

I'm somehow ashamed for the fact I have already been given the chance to play with an actual WP34S (I was actually given the calculator plus the connection cable themselves...) and did not have the time to read the manual and try it out. Just turned it on, tested a few features I was mainly curious about, and that's all so far.

Cannot wait to get back posting the way I want to...


Luiz (Brazil)

Edited: 2 Sept 2012, 10:37 p.m.

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