translated from the readme:

But what is it?
=> A library that allows you to integrate the keyboard sony in just a single line of code!
=> It can also easily retrieve information about the PSP


Ha yes, and how do I install it?
=> Very, very simple! (Imagine that you have installed pspdev in C: pspdev ) simply follow the following steps:
1. Libpsposk.a copy the files in the folder C: pspdev psp SDK lib
2. Psposk.h copy the files in C: pspdev psp SDK include


And to use it?
=> Look at the sources of sample provided with is the bare minimum required (and more);)
=> Do not forget to move your kernel 5.xx and put the samples in Game if you want to test them.


Note:
- Remember to include your *. c prototype "psposk.h" (and "png.h", "graphics.h" if you want to use the libpng)
- Remember to include your Makefile in the library-lpsposk (and lpng-lz if you use the SonyOskPng)

Changelog:

(v1.5) Change from v1.4:
----------------------------------
- Added an option that lets you choose the language of the keyboard (or automatically selected by the developer)
- Added a verification of the existence of the image when using the function SonyOskPng to avoid crashes if you forget it.
- Updating the library to 5.xx kernel (the keyboard could hang on 5.xx)
- Updated samples, and adding the sample SonyOsk_langue_Sample


(v1.4) Change from v1.3:
----------------------------------
- Adding the function SonyOskInfoPsp () which allows you to retrieve information about the PSP and the user. (more info in the psposk.h)
- Change the variable type for the title and description (short passage in char), so really easy to use! (Akabane thank you for the idea and function conversion;))
- Best settings refresh keyboard.
- Bug fixes.


(v1.3) Change from v1.2:
----------------------------------
- Optimization of compatibilitée with libpng and graphics.h, no worries at this level! As well against think everything (regadrez the sample;))
- Function SonyOskInfoPsp () removed temporarily pending debug.


(v1.2) Change from v1.1:
----------------------------------
- Adding a new function for various info on the PSP and its user.


(v1.1) Change from v1.0:
----------------------------------
- More needs to declare the text description intext and if we do not want it.
- Possibility to use the keyboard with the OS or with the libpng.
- If used with libpng, possibility to put a background behind the keyboard.
- Changing the speed.
- Passage of the keyboard in French.
- Grosse optimization of the code.