This is a simple plugin I made a long time ago for my personal use. I just found the source code while going through some old stuff on my computer, so I thought I'd clean up the code a bit and release the plugin.

I realize that there are other plugins that feature similar functionality but I wrote my own because I wanted to be sure its coded optimally, as there are a few careless ways in which these functions can be improperly used (the point of this after all is to conserve battery life).

It does the following when the Hold switch is enabled:
* Switches off the LCD backlight.
* Switches off the actual LCD screen.
(This is important because the backlight and actual screen are two different things. You can have an image being displayed on the screen while the backlight is switched off, such that you can see the image if you use a flashlight. You can also have the screen switched off while the backlight still illuminates the powered off screen.)
* Underclocks the CPU to 61MHz
(Sony has changed the clock speed functions such that only certain combinations of speeds work correctly. Simply trying to underclock to arbitrary values will result in the CPU simply running at the stock speed. I have verified that Hold+ successfully underclocks to 61MHz.)
* The original screen brightness and clock speed are restored when the Hold switch is released.
* Prevents the PSP from going into suspend mode if you accidently push the power switch too far when turning off Hold mode.
* Allows operation of the PSP with the display turned off, to change volume, skip songs etc.

Usage:
Turn on the Hold switch to automatically disable the display and underclock the CPU. Turn off the Hold switch to return the CPU to normal speed and enable the display.

If you push the ANALOG UP button when turning off the hold switch, the display will remain switched off and the CPU will remain underclocked, but you can operate the PSP. This is useful if you just need to adjust the volume, fast forward/rewind, or to skip to the next song, without unnecessarily turning on the display. To return to normal, just press the Screen button.

If you push the ANALOG UP button when turning on the hold switch, it will only lock the keypad like normal Hold mode. The display and CPU speed will not be changed, so that you can watch videos etc. with the keypad locked.

Installation:
You can install it in the seplugins folder, and make an entry in VSH.txt. Thus it will be active in the XMB. Its also possible to use it in games by adding it to GAME.txt, but some games may crash etc., if the CPU is underclocked to such a low value.

Optionally, its also possible to install it in your PSP's flash0 so that it will work without a memory card. For this you can use FreePlay's "NewBTCFNedit" and enable it for VSH mode in the all the PSPBT?NF.bin files. Add it after vshmain.prx.

Credits:
Thanks to adrahil for helping with preventing the suspend mode.

Changelog v2.63
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Fixed a bug where turning off the Hold switch very fast (less than 100ms) to the Power position would cause the PSP to enter standby.

Note:
I never made any previous hold plugins, those are not by me.

If you want to change the clock speed to your own values, you can use a hex editor to change them. The offsets in the file for v2.63 are
0x2F4, 0x2F8 - CPU,GPU (Both should be same)
0x300 - Bus (Should be half the CPU speed or less)

The values should be entered in hexadecimal. The default value for CPU/GPU is 3C (60 MHz in decimal) and the default value for bus is 1E (30 MHz in decimal).

Note that simply using any arbitrary value will not work. You will have to test and see which values for CPU/GPU and Bus speed work.
.

Lockdown allows you to password protect your PSP from prying eyes.
It also protects the Recovery Menu so that the protection can't be disabled without considerable effort (or by unbricking).

Features:
* Completely customizable GUI
* Uses PSP keys like Square, Cross, Circle etc as password, instead of fumbling with an on screen keyboard
* Fully configurable from the PSP
* Protects Recovery Menu as well
* Supports 2 modes of operation: 1st mode will only ask for password when the PSP is rebooted or powered on. 2nd mode will ask for password every time the XMB is launched, such as after quitting a game etc.
* Application errors (Game could not be started, etc) will be displayed normally in the XMB unlike other password programs which won't display these messages. So you know why you were sent back to the XMB.

If you have problems getting it to work, you can try using the debug versions from the "debug" folder in the archive. They will display any errors that occur.

v3.0 Changelog
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Added support to customize the GUI.
Optimized memory usage.