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This has been asked before I'm sure, but I was thinking about selling my HP-48GX, because I never have and never will use any of the expansion slots, and I never have needed the extra memory provided by the GX. My question is, since I don't need the memory for storage, am I going to see a downgrade in performance going to the HP-48G or should I try to find a HP-48G+. As I understand the sole differences between them are as follows (and please correct me if I'm wrong):
GX = 128 KB Memory + Expandable,
G+ = 128 KB Memory + Non-Expandable,
G = 32 KB Memory + Non-Expandable.

I'm just seeing that I could sell my current GX (because I'll never use it to it's full potential) for $200 + and get a G for $50 or so, and never notice the difference in features/performance for my personal application. Thanks for any responses. Also, G+'s are hard to find on ebay if at all. Any ideas. Thanks!

If you just use the calculator as it is without any downloaded software, you probably won't notice any difference or that the plain G is actually a bit more spunky (turns on quicker, no hesitations, which is due to 32K RAM vs garbage dump and longer memory checks with the 128K RAM).

32K is plenty of RAM for personal programs and solver use, if you don't do much in the way of customization.

The G+ has the same 128K as your GX, but no expansion. The G+ sells for $75-100 generally (or did, I seldom check ebay anymore). You might also consider the new Hp48GII, but buy first before you abandon you 48GX (if you hate the keyboard or lack of the nice large enter key).

Do a quick memory check on your 48GX. If you have used over 20K or 25K (and have had it for years), you probably won't need the extra RAM. However, if you have used over 30K of RAM, you would be out of RAM by now on a plain 48G (of course you could have just loaded you 48G up with variables that you wouldn't miss if you did a reset).

Have you ever made use of any downloaded software? This is a great resource and you might visit hpcalc.org to look over what is freely available. Once you downgrade and then want your old 48GX back, you may pay even more for a 48 in much worse shape than what you already have.

A 48G has just enough memory for personal programming and one to two programs depending upon complexity.

A 48G+ has 128K RAM which would allow you to add CAS and some sophisticated programs.

A 48GX has 128K RAM plus the ability to add another 128K RAM to port 1 and 3.5 Meg to ports 2-30 (at 128 K RAM per port). The most common memory config is a 128K and a 1 Meg card. Klotz (in Germany) has these for about $40 and $70 respectfully. This option will not be available if you do not have a GX.

While you may make $100+ in this quick exchange you may or may not end up with a good 48G replacement (ie you will be at the mercy of another ebayer's description). That is why I suggest looking at the new 48GII. However, be warned, its keyboard isn't of the same quality of the older 48G series, though it is a big improvement over the recently discontinued 49G (which was replaced by the 49G+)

48Gii is a 49G+ with only 80K RAM and a serial port. No large enter key, same keyboard layout as the 49G+.

I would keep the 48GX anyway. Having the extra memory is nice just in case you would want to load any future programs.

One more question:

I've seen people offering "HP 48 G with 128kB" at ebay several times. Is this calculator configuration possible? If true, how could I detect how much memory my HP48G contains? The MEM command returns something different, at least not a power of 2.

This may be a dum question - sorry - but it fits into this thread.

Thanks for hints!

It isn't all that hard to add 128K RAM to a 48G and there are articles on Hpcalc.org on how to do just that.

If you calculator was never opened, it don't have 128K.

Memory check (keystroke sequence):

-> memory



This will tell you the size of the variable (which is unimportant probably, but the next line down tells how much memory is available.

If you really want to know how much is in your 48, you do a memory reset which clears out all variables and programs, then do this. You will get 28-30K for a 48G.

Thanks, Ron!

So, the display says "Mem Available" is 251603 bytes. This is a bit more than 128k Bytes. According to my old professor in Theoretical Physics, a factor of 2 may be neglected. So I am happy with "128k +" in my HP48G. Or did I misinterpret anything?


Most likely a case of failing eyesight (or poor light if you need an excuse).

But it is also possible if you purchased your calculator from someone or some German firms add the extra RAM onto 48G's. The 48G can address 256K of RAM directly if you have that much RAM available and merge port 0 and 1.

Ports 2-30 cannot be merge and you would look for those by using these keystrokes:


If you really have 251603 bytes, you should also see port 2 and 3 as well as the RAM for the 48G is sold in 32, 64, 128, and 512K RAM chips. There would be a good chance that they just used a 512K chip (and you may see port 2 & 3) or doubled up on the 128K (and then you wont see any other ports). You may try the command PINIT.

Chances are you just WISHED you had 256K Ram and you really have only 25K RAM available. Then the rest of this is moot.

Though I hope you do. It would be a nice plus. Did you buy you 48G from someone or from a German retailer (the Ram upgrades seem to be most popular in Germany)?

Well, contrary to your assumption, I am still able to count digits up to 6 ;) And I find 251509 bytes following your instruction, PPAR is only 63 bytes - I did a reset recently. Following your last response, I see 2 directories ( :0: and :2: ). In :2: I find "Library 986: P.C.T. ...". Does this help to clarify the matter?

I bought this calculator from a German in Ebay. The first vendor apparently was a German supplier, according to the label on the backside. No further info available.

OK, eyesight is canceled as cause now. I am looking forward to your next theory.

P.S.: I have no acces to a manual right now - I will read later. Physicists never read manuals. ;-)

Hi Walter, you have exactely 384K ram in your configuration. Port 0 and 1 are merged so you have 256K available in port 0 (minus the memory used to manage your system). And you still have another port available in port 2. This memory is a back up memory to save data. The library you have in port 2 is a memory manager which is very usefull when you manage libraries. Enter 2 PVARS and you will see the memory still available in port 2. I think you should have something around 100000.
The program stored in port 2 are not erased when you clear the memory of the calculator. You must do it manually ( functions DETACH and PURGE). Hope it will help you.

Well now that you CONFESS to owning a 48G of German orgin, and your follow up response, I congradulate you on a great system.

You have a very nice system. You might also check your clock. If it runs fast ie 2x fast, you also have a clock doubler. This is also common from German suppliers. Clock is then worthless, but the calculator will be fast in comparision to any other 48 or even a 49G (I DIDN'T say G+)for most operations.