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From: John H Meyers on 18 Sep 2009 23:26
On Thu, 17 Sep 2009 12:52:05 -0500, Stephen Mendes wrote:

> Is it true that ALL the plug-in cards for HP48
> used binary code not compatible with HP49/50 ?

Programs call most functions using direct ROM addresses.

Due to extensive recompiling and reorganizing of ROM,
most (though not all) HP48 series ROM addresses
are different from HP49/50 series ROM addresses,
even for the identical functions.

Even some library functions have different "function numbers"
in each series.

That's why HP48 series programs, in executable form,
are nearly 100% incompatible with HP49/50 series,
even if the "source" can potentially be directly recompiled
(which is very often possible, but not always).

Many an older contributed program or "library" has been "ported"
from one series to the other, by decompilation/recompilation,
but this often requires
the extensive work of a human brain to perform;
it is sometimes easy, and other times tricky,
depending on the nature of the original program or library.

> Are there any sources still selling new HP48GX ?

Is there still any unmined gold in California?

Maybe, but probably takes a lot of prospecting to find,
as of this date -- try eBay, or hpmuseum.org sales listings.

> Are repairs (screen change) available on HP48GX ?

If you are a screen transplant surgeon,
and can find a better screen in an otherwise dead carcass.

Perhaps there are also "screen rejuvenating" operations,
e.g. to reverse effect of long-applied pressure, or whatever.

> Somebody just gave me one more card NAVCOM 48 which is
> HP-48 Marine Navigation Library written by Applied Programing Systems
>
> This person has an HP-48GX with an LCD that has gone black (I
> understand it is a fairly common problem with older LCD's)
>
> They wanted to buy my last working HP-48GX but I refused to sell it
> for any amount of money..... however, I would still like to advise
> them of their options.

Emulators of HP calc series also exist for various platforms;
for example, I have a very old WinCE organizer which,
thanks to C.G., runs EMU48 and makes a perfect HP48GX,
and even does things which my original could never do,
such as fit into my shirt pocket :)

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