Boot ROM.
flash the bios
CMOS or BIOS configuration settings
Hacking the firmware depends on the PSP's motherboard, not the current firmware installed. If you're asking whether or not it can be made into a custom firmware, then the answer is yes, but all homebrew would have to be rewritten for it.
It is called Firmware and it holds the basic software needed on the motherboard.
It's not the firmware that matters, it's the motherboard. A hackable motherboard can have custom firmware installed no matter what version of the official firmware it uses. 'Unhackable' (at present) ones can't have custom firmware installed at all right now. All phat PSPs can be hacked, most slims can, but recent ones can't, and at present, PSP-3000's can't at all.
The motherboard is located on the form factor
Programs stored on ROM chips are called firmware. The motherboard stores the keyboard controller support program on the ROM chip.
BIOS
Depending on the context, those could be referred to as hardware or firmware.
The hard drive is not located on the motherboard.
To answer your question it is a mother board. Notice the spelling. The firmware of the computer runs from the motherboard (firmware is important software needed to run hardware correctly). Generally referred to as a "Mobo" the motherboard runs everything your computer uses to run, it is essentially the heart of your computer. The graphics card, the power source, the Disk drives, and much more all depend on the motherboard to centralize and keep your computer running.
The controlling program for the Power-On Self-Test (POST) is physically located in the firmware of the computer's motherboard, specifically within the Basic Input/Output System (BIOS) or Unified Extensible Firmware Interface (UEFI). This firmware is stored on a non-volatile memory chip, allowing it to remain intact even when the computer is powered off. Upon startup, the BIOS/UEFI executes the POST to check the hardware components before booting the operating system.