Internal Memory VS External Memory

The PlayStation 2 doesn’t have an operating system, making it handle all the storage by each application separately! Programs can use the firmware’s built-in modules, but these only exist for the internal hard drive. So depending on the program and device, different logical structures are supported. In the following material, I try to describe the differences, which as much as possible can be – and often are – confusing to someone so far unfamiliar with the PS2 homebrew scene.

External Memory:

USB

The first ever support for additional storage was USB (i.e. flash drives), which was even implemented in a few games (e.g. “Gran Turismo 4”). Initially, compatibility with devices was low and for some reason higher if the file system was not FAT32 but FAT16 or even FAT12 (there were also times when users juggled “USBD.IRX” files because just such a module from just such a game or application, supported their device). Due to the fact that many programs have closed code and their authors abandoned them long ago, the universal medium is and will remain a flash drive: with a partition table MBR and one partition with any of the file systems I mentioned earlier.

With the advent of the PS2ESDL (game loader, one of the alternatives to the USB Advance/Extreme and, of course, the Open PS2 Loader) came support for i.Link (a FireWire 400 compatible standard), which was briefly installed in PS2 consoles (present in SCPH-30004R models, for example). It has never gained popularity, and requires external power supply for, say, a hard drive or pendrive.

MX4SIO

A few years later, the MX4SIO, an SDHC/SDXC card reader that plugs into a memory card slot (not to be confused with a PlayStation 2 Memory Card, which it is not and cannot be), also joined the family.

Block Device Manager (BDM)

All of the above mess of modules (“USBD.IRX”/”USBMASS.IRX”/”ILINK.IRX”) has been replaced by the eponymous BDM, which has unified support for all of these devices, multiple partition tables (in addition to MBR, also GPT) and multiple file systems (such as the recently added exFAT). Thus, we can assume that BDM is now synonymous of support for all EXTERNAL memory (although in the case of BDM used, for the time being exclusively in OPL GD, also internal).

  • Interface: USB, i.Link, MX4SIO
  • Partition Tables: MBR, GPT or none (the last two exclusively by OPL GD)
  • File Systems: FAT12, FAT16, FAT32, exFAT, EXT2 (the last exclusively by E2OPL)

Internal Memory:

A separate world is INTERNAL MEMORY, i.e. a PATA (Parallel ATA) hard drive, connected to (depending on the console model) a special external enclosure via PCMCIA (SCPH-1xxxx) or Network Adaptor via a dedicated port (SCPH-3xxxx/5xxxx models), or if you solder well ;) then directly to the motherboard (SCPH-700xx). Even if the Network Adaptor is unlicensed or a counterfeit and/or with a board replacing the old PATA by the newer SATA (Serial ATA), such a solution is most often referred to simply as IDE (as this is the standard). You may still encounter the term “iHDD” (from “internal HDD”), but it is rarely used.

NOTE: Connecting a hard drive via USB or i.Link, does not make it an internal drive!
  • Interface: PATA (SATA, after board replacement in Network Adaptor)
  • Partition Tables: APA (native), GPT or none (the last two exclusively by OPL GD)
  • File Systems: PFS (native), EXT2 (Linux), RFS v3.5 (Linux), RAW (e.g. game disc images for the PS2), exFAT (the last exclusively by the OPL GD, but not on the APA)