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+--- Thread: HP PRIME - Available Memory / Memory in use ... (/thread-3737.html)
HP PRIME - Available Memory / Memory in use ... - wChris79 - 04-28-2015 04:29 PM
Good evening,
I have a problem with the display of the memory capacity of my HP Premium. I do not know how I should understand it.
When I do SHIFT MEM Info calculator returns me: Memory: 8.16 MB.
But I thought of 32 MB to start new machine without program or app or matrix / list etc ...
Knowing that I have about 57 KB and 20 KB programs remarks should I not have to display: 31.92 MB of available memory: 32 MB - (57KB + 20 KB) ...?
I also have a mention in this display: Storage: 197.71 MB.
Thank you for your help,
Christian.
RE: HP PRIME - Available Memory / Memory in use ... - debrouxl - 04-28-2015 05:25 PM
The Prime's OS is loaded from the 256 MB NAND Flash memory to the 32 MB RAM during the booting stage, and runs from RAM, using at least half of it. That's because NAND Flash memory can be accessed exclusively in paging mode, and it's therefore unsuitable for code execution.
There's another type of Flash memory: NOR Flash memory, which is random access and therefore eXecutable In Place, but is usually fairly slow, and most of all, (much) more expensive than NAND Flash memory for a given capacity.
The high-end models from both HP (Prime) and TI (Nspire) use NAND Flash memory; calculator families based on older technology, e.g. the Flash-equipped subset of the TI-Z80, TI-68k and TI-eZ80 series, use XIP NOR Flash memory chips.
RE: HP PRIME - Available Memory / Memory in use ... - wChris79 - 04-28-2015 05:45 PM
Thank you very much for your explanations.
So if I understand the OS occupies about 24 MB RAM remains about 8 MB for my programs, apps, comments and other variables. Is that correct?
Thank you for your help,
Christian.
RE: HP PRIME - Available Memory / Memory in use ... - cyrille de brébisson - 04-29-2015 05:42 AM
Hello,
No, that is a little bit more complicated than that.
Flash storage is used for permanent storage and is 256MB.
Out of that a portion is reserved by the OS for itself, future updates and buffers (all together around 64MB). This leaves ~ 190MB for the user.
All your data is saved there, lists, matrices, programs, comments, apps....
RAM is 32MB
But, as stated, the Flash is only storage, it is not possible to work from flash, so the OS has to load itself completely in RAM to execute. This takes around 20MB.
Then the OS has to 'work' to do that, it also needs RAM. For the screen, various buffers, datastructures, flash cache (for file access...)... This takes an additional 4MB...
This leaves a total of 8MB of 'free' ram.
When a user program, list, matrice is used, it is loaded in RAM. It is not loaded unless it is needed. so you can have more user data in flash than there is RAM available in the same way that you can have more user files on your computer HD than you have RAM on your computer.
Cyrille
RE: HP PRIME - Available Memory / Memory in use ... - wChris79 - 04-29-2015 04:56 PM
OK. Thank you for the explanations. Things are clearer now. Thank you again.
Christian.
RE: HP PRIME - Available Memory / Memory in use ... - raider - 05-06-2015 12:51 PM
Hi,
I am fairly new to the HP Prime. If I am understanding this correctly, we really only have about 8MB or so for programs. My Calculator is now showing 10.11MB when pressing Shift-MEM.
With 8 to 10MB of space, will we be facing a memory full issue very soon if we have a lot of programs? What sort of size are most programs? Just need to get an idea how much programs we can store before running out of space.
Thanks
RE: HP PRIME - Available Memory / Memory in use ... - Marcio - 05-06-2015 01:24 PM
Most programs are usually 10-50 kB.