Well when opened you will see the following:
(This is for 5.02 GEN-A..can't test 5.03 GEN-A for you but shoudl be the same)
GEN VSH Menu
Game Category:Plugin by Bubbletune integrated into GEN firmware.Lets you categorize your games.CPU Clock XMB:This changes the CPU speed on the Xross Media Bar(XMB-A.K.A.-Main Menu).Default speed is 222Mhz.When set below 100 you will notice a slowdown in the menu but at 133 Mhz it is still decent and will conserver battery life.Now if you have no VSH plugins enabled set to 133 Mhz to maximize the battery life.Originally Posted by Original Readme
CPU Clock Game:Lets you change the processing speed while playing games(I.E.UMD's,ISO/CSO)Default speed is 222Mhz.Most will say that setting to 333 will increase the speed of soem games.(Drains battery faster at this speed)
USB Device:Let's you change what you access when you toggle USB.
>Memory Stick:Toggles Access to the Memory Stick.
>Flash0:Access Flash0.This is essentially where your Firmware is stored.I advise you NOT to mess with it if you do not know what your doing.
>Flash1:Used to the store XMB settings
>Flash2:In firmwares 3.00 and up, this contains the half of the DRM for Sony's official PS1 emulator(the other half being in the flash0)
>Flash3:Currently unused and about 1mb in size although in custom firmwares it can be used along with flash2 to redirect firmware elements such as fonts.
>UMD Disc:Toggles to the UMD in the Drive(Lets you copy it to PC therefore backing up your disc to be able to load off the MemStick.
UMD ISO Mode:Lets you choose the ISO Driver you want to use.They are as follows Normal,OE isofs,M33 Driver,and Sony NP9660.
>Normal:Requires you to have a UMD in the Drive.
>OE isofs:ISO Driver from the OE series of Firmware..not widely used anymore.
>M33 Driver:Created by Dark_AleX
>Sony NP9660:This Driver uses the Sony ISO Loader used for PSN games to load generic ISO files.
Now depending on who you talk to they will tell you to use M33 Driver or the Sony NP9660 Driver.Now some say that one is faster then the other and one has better compatibility then the other..I personally use M33 and have had zero problems.
ISO Video Mount:This is used for playing backups of UMD VIDEO ISO's.(Requires you to have a UMD in the Drive.
(These 4 are kinda self explanatory but whatever)
Shutdown Device:Turns the PSP Off.
Recovery Menu:Loads the Recovery Menu(Normally accessed by holding R-Trigger when the PSP is turned on)
Reboot Device:Reboot's the PSP.
Exit:Exits the VSH Menu.