HP49+ Memory--scratching my head



#2

I am still navigating my newly acquired HP49G+, and have more questions that seem deceptively simple but I really have no clue.

The full length user's guide (on the CD) indicates that the calc has a total of 2.5 MB, with, I believe, about 1 MB allocated to system use. There is supposed to be 1.5 MB of user-accesible memory as follows--240 KB Port 0 (IRAM), 255 KB Port 1 (ERAM), and up to 1085 KB Port 2 (Flash). This is what the memory allocation seems to be in the HP49G, at least from what I can see in my emulators.

But when I remove all objects I can find from memory and do a factory reset, the File Manager tells me I have about 240K Port 0 memory, 127K Port 1 Memory, and only 768K port 2 flash memory.

The back of the users manual that packs with the calculator indicates that the calc has 2.5 MB in total, with 512K RAM and the rest flash ROM.

So, my simple mind wonders, what happened to about 128KB of my RAM and 320 KB of my flash ROM? Apart from CASDIR, there is nuthin' left in this calc's memory, that I can find anyway....

According to VERSION, I have 1.23. The calc has not been upgraded to 2.xx.

I know that the HP49G+ is not well loved around this forum (purists don't even consider it a true HP), but, for the most part, I am finding it to be okay, I got it for a good price, and I am keen to demystify its quirks so as to maximize my enjoyment of it.

Les


#3

The relevant HP web page gives memory allocation numbers a bit closer to my experience (I have a little more RAM, a little less flash), but that still does little to diminish my perplexity.

Interested for a history lesson on the memory allocation issues has the HP49G+ has evolved over the years.

Les

#4

Look at the old thread:

http://www.hpmuseum.org/cgi-sys/cgiwrap/hpmuseum/archv015.cgi?read=79165

Search for: 'Little memory in my HP-49G+, as well ...'


#5

Thanks, Hrast. Nice to know I wasn't hallucinating....

The manual on the CD-ROM is definitely wrong,then.

Les


#6

The missing 128k in port1 can be accessed but you need to use hpgcc.

Arnaud


#7

Thanks. But that begs an interesting question--if that 128K isn't accessible to the average user, what's in it? Or is it empty but sequestered away?


#8

From what I understand,, the 128K in port 1 it is taken for use by the ARMOS running the emulator. However, it never seems to use it at all more than 15-20K. The rest is free for use in hpgcc. I think the reason it all had to be devoted to the emulator is due to old saturn issues, but I am probably wrong. =)

TW


#9

What emulator are we referring too?

I am using a "real" HP49G+ here. Mebbe, as one who knows nothing about hardware level programming-speak, I am misunderstanding your use of the word "emulator".

I must admit that I find it perplexing the antecedent 49G actually had MORE user memory available in ports 1 and 2. Some progress!

Les


#10

The real HP49G+ is itself an emulator. It is equipped with an ARM processor, and this processor runs emulation code to emulate the Saturn processor used in the HP48S/SX/G/G+/GX calculators.


#11

Or actually, it emulates a modification of the Saturn processor used in the 48 series and 49G.

And yes, the manuals are wrong, or at least, not that much memory is actually available to the user, even if it is physically present in the calculator. Note that this is true of at least all RPL calculators starting with the 28C, where MEM returns only 1672 after a memory clear, instead of the 2048 you might expect. The discrepancy seems particularly large with the 49g+.

Regards,
James

Edited: 3 June 2006, 12:50 a.m.


#12

PS:

By disabling last command lines, last arguments, and UNDO, I can get MEM to return 1693 on a 28C; still quite a bit short of 2048.

Regards,
James


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