GP2X View Your Gp2x Ram As An Image

[notaz]

http://notaz.gp2x.de/misc/ramview.zip

I find it fun to play with this. After loading some app you can see where it kept it's framebuffers. After loading quake you can find some player skins and stuff.

You can see with this that GP2X, like many other devices, has it's RAM mirrored. The mirror locations are 0x08000000, 0x10000000, 0x18000000, ..., 0x38000000

What I found really strange is that some things can survive a cold reboot, up to a minute and more! It starts slowly degrading after that, though. I wonder, is that the RAM itself responsible or do just some capacitors keep their charge?

Readme below:
CODE

ramview r1
(c) notaz, 2008


About
-----

This program allows you to view any location of GP2X RAM as an image.
It works by simply altering display controller's RGB layer source pointer.

Three numbers on top-left mean the target address, bits per pixel and pixels
per line.


Controls
--------

left, fight: move the display pointer back/forward by 1 pixel
up, down: move the display pointer back/forward by 1 line
L, R: move the display pointer back/forward by 1 screen
VOL UP, DOWN: change the image stride (pixel count for 1 horizontal line)
Y: change BPP setting in display controller (4, 8, 16, 24)
(note that palette is not set for 4 and 6 bpp modes, palette
is left to whaever previous program is used).
A: jump between some "known" framebuffer addresses
START: exit program


Disclaimer
----------

This program can set some hardware registers to "bad" values, so if you
manage to harm your GP2X using this, it is your own fault.
I cannot be held responsible to any damages this program may cause.

 

[Squidge]

Has someone been reading CDA, or just thought it would be a fun idea?

 

[PokeParadox]

Regarding the RAM keeping some of the data, I have noticed that on occasion, you can see remnants of certain applications on boot-up for a split-second.

 

[spookyln]

great,
like in old amiga times when i played with some MOD and bitmap rippers

 

[Kramy]

Regarding the RAM keeping some of the data, I have noticed that on occasion, you can see remnants of certain applications on boot-up for a split-second.

That's a known hardware exploit of RAM. Call it flawed technology.

Some hackers cracked some computers by using a bootable tiny OS that dumps the entire contents of memory. Apparently if you cool/freeze the RAM, it can retain information well beyond a couple minutes.

 

[aaron11193]

hmmm.... i always thought that seeing the previous screen at boot was just because the LCD hadnt fully cleared yet.....? like the old Gameboys where the screen slowly faded away...

 

[HenrikE]

great,
like in old amiga times when i played with some MOD and bitmap rippers

Yep - was about to suggest setting stride and specify width & height for saving. Almost there...! I once rescued a font and a logo from a prod from 1991 where only the binary survived, with a ripper. Also, you could use it steal nice little pics/anims from games etc to use as forum avatars and whatnot

Kramy: Not flawed technology, memory technology. 1 minute sounds like a lot - but I don't know how long there is some current going after the "LED goes black", so to speak. Usually there's a big cap for the power, a small cap on the board as filter, and the RAM itself is supposed to hold a charge until the next refresh, which is 63us or so in many designs. I'm coming from 5V, so I know too little about these low power chips... if the chips are overspec'd, or there are remnant currents going to the clock, timing chip,...