Free42 on a Palm Z22


Hi all,

    I've recently (and unexpectedly) been presented with a Palm Z22.
    This is an incredibly small (and cheap, $99 or less) PDA with a 200-Mhz ARM processor, color screen, a pleasantly solid built, and 32 Mb of RAM, which cosmetically and functionally would be perfectly at home in the futuristic settings of "2001: A Space Odyssey".

    Until now, I've never owned or been interested in PDAs, and while I still don't want or need it for its PDA functionality, I did remember that Free42, a nearly perfect HP42S emulator/simulator by Thomas Okken, had many different incarnations, including one for Palm OS, so I decided to give it a try.

    I duly sent an e-mail to Thomas asking for advice, and he promptly sent back a very kind reply, which dispelled all my doubts, so I went straight to it and, lo and behold, this is the result:

    Free42 running on my tiny Z22

    Don't let the picture size fool you (look at the size of those fingers!), this device is actually the size of a small cellular phone. Alas, the picture doesn't really do it justice at all, the display is
    extremely sharp and very easy on the eyes.

    Also, much to my surprise I've found that Free42 is very useable
    in the Z22 ! Matter of fact, it's easier to
    use than an HP42S proper, because it's faster
    and less tiring to pick up numbers and commands
    with the small stylus than physically
    pressing buttons with your finger. Actually,
    I became accustomed to it so fast that I'm now
    contemplating using it regularly instead of
    my nearly-irreplaceable real 42S or a mouse-driven Windows version, because using the stylus is much faster and less
    tiring than clicking with the mouse.

    Also, it runs quite fast. I've loaded the ARM version
    in its BCD (decimal, which is essential for compatibility) incarnation, and
    tried this program (RAD mode):

           00 {23--byte program}
    01 LBL "FREE42"
    02 1E4
    03 STO 00
    04 LBL 00
    05 1
    06 SIN
    07 DSE 00
    08 GTO 00
    which computes 10,000 times the sine of 1
    radian and executes 50,000+ steps, 10,000 of
    which are trigonometric computations, in just
    20 seconds. That's impressive speed !

    All in all, I've found the combination of Free42
    plus Palm Z22 an extremely pleasant one. The Z22 is
    much smaller than an actual 42S (or even an HP-15C),
    takes no space in your pocket and weighs next to
    nothing, and it's also extremely pleasant to use,
    even effortlessly I migh add, excellent screen, and incredibly fast so, unexpectedly, I'm extremely pleased with the
    combination though I was trying it out of mere
    curiosity, with no plans to use it regularly.

    Now I feel this is indeed the future of RPN
    calculators: to be run in such convenient PDAs
    (small, fast, ergonomic, inexpensive) in the form
    of such well crafted emulators/simulators as Thomas'.
    Having that much power in a $99 device so small I can
    easily conceal it in my hand is awesome !

    Thanks a lot to Thomas for his kind help and most
    specially, for the incredible amount of hard,
    disinterested work necessary to create Free42 in the first place and
    offer it freely on so many platforms. It's
    certainly praiseworthy.

Best regards from V.

Edited to correct an omission kindly reported by Les Wright, see below. Thanks, Les !

Edited: 1 May 2006, 9:24 p.m. after one or more responses were posted


Yes, Free42 runs really great on palms. On my Palm Treo 650, it does an amazing job.

You can also probably run the Power48 emulator and have access (if you want) to the HP48SX, HP48GX and HP49G calculators on it.

Enjoy the new friend!


Thanks so much for your feedback and advice, Gene, but you know, I find RPL ... well, yes, RePeLent ! :-)

Best regards from V.




You can also probably run the Power48 emulator and have access (if you want) to the HP48SX, HP48GX and HP49G calculators on it.

IIRC, Power48 requires a 320x320 or 320x480 screen; the Z22 has a 160x160 screen, so Power48 won't be very usable, if it works at all.

- Thomas


My mistake! I keep thinking these palms are all hi-res 320x320 now. :-)

And, I know your thoughts on RPL, Valentin. :-) I like exact mode on the 49g series machines, however, and the Power48 emulator makes it really easy to have it around.


Free42 works well on the Palm TX, and so does the Power 48. One exception for the Power 48, I am unable to run the 49 ROM on the it, and I used both the card and its main memory. For now the 49 is stuck on the card.

I am currently using Power 48 to run the SX.


Hey Valentin,

I am glad to see you happy with the Z22! I own one too :) and it is a pleasure to see YOU praising an electronic device of modern times !! ;)

You can also run P41CX on it (I added support for Angel Martin's ROMS and others, let me know if you are interested), and KK-12C.

If you are still interested in a 15C after running the much more powerful Free42, you can still consider a cheap PocketPC with Lygea's excellent Pocket15C simulator...

And yes, big thanks again to Thomas' awsome job !!




I love the Free42 too. Go to Thomas's website and fund his trip! It is worth it!

But your little test program has a typo. I think you need to store that 10000 in register 00 for the DSE 00 instruction to work.

I am sure it must be a typo. I am a real amateur--if I can see this anyone can ;)

That said, when I run your corrected code on my new TX, it takes about 9 or 10 s (with the printer set off--very important, as the first time I tested in TRACE mode and it is obviously much slower.)

I am glad you discovered some use for a PDA beyond mere electronic datebook. I took my first Palm back a few years ago after a few hours since I had no clue what I would do with it. Now, the calculator emulation is the most important use--indeed, I got a 320x480 screen unit just so I could benefit fully from the more attractive skins for Power48, P41CX (which I love despite the fact that the printer emulation is flawed and will likely never get fixed), and, of course Free42.

Thanks for you optimism and enthusiasm.



Hi, Les:

    Thanks a lot for pointing this glaring omission out, I've already corrected it in my original message above and I've also included a proper footnote giving you credit for the correction.

    On my behalf, I must say I posted that code very, very, very late in the night (even for me), and I was very eager to go to bed, so I didn't spot the omission.

    And yes, I'm now very enthusiastic at the future of HP calculators running as nearly perfect emulations/simulations in the always improving, new generations of PDA devices. Free42 running on my extremely small Z22 is a real marvel to my eyes, and quite useable despite the size.

    Thanks again and

Best regards from V.


Here is another testimony to Free42's speed.

I tried running your little test program on P41CX, again on my Palm TX, with CPU speed settings at maximum, battery saver off, and printing disabled.

I stopped the routine after several minutes (I don't know how long) since that flying gull was giving me vertigo. RCL 00 had only counted down to 8300!

Bottom line: P41CX is slow--indeed, in practice it is even slower since the app is not usable at max cpu settings--the keypad is far too sensitive and functions "NULL out" regularly.

I think this exemplifies the difference between "emulator" and "simulator". Thomas told me Free42, as simulator, would be fast. He wasn't kidding.


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