Manufacturers of consumer electronics are constantly revising their designs over the lifetime of each product, generally for four reasons:
- Yield improvements — fix flaws that caused lots of warranty returns
- Cost reduction — use cheaper or fewer parts, so that profit margin increases or the retail cost can be lowered (or both)
- Part refresh — sometimes manufacturers stop making parts (for example, 64MB memory chips), so they’ll start using “better” chips because they are the only ones now available
- Security — anti-modchip modifications
Most people only think about the last one, but the first three are far more common. I think Sony has most actively revised their designs — aren’t there something like 30+ revs of the PS1, 15+ revs of the PS2, and several of the PSP and PS3? Microsoft had 5 or 6 revs of the Xbox1, and 3 of the Xbox360. Nintendo has had relatively few — perhaps this is because they have never sold their consoles at a loss, so they have less incentive to retool their factories to bring their costs down. (It’s rather expensive to redesign a PCB and then retool your factories to make new ones, and you add some risk of creating new hardware problems and increasing your failure rate.)
Focussing back on our Wii, we can consider the following things as being more or less independent:
- Updates to the disc drive
- Updates to the “big chips” (Hollywood, Broadway)
- Updates to the main PCB
We’ve seen several updates to the disc drive; these are so well-known that people even put up entire websites that track them! Off the top of my head, there was DMS/D2A, D2B (like D2A, but changed mask ROM on one of the chips — probably for reason #1), D2B with cut legs (reason #4), D2C (reason #4), D2C2 (reason #4), D2E (unknown — reason #1?), D2E + epoxy (reason #4), “D2nothing” (perhaps reason #2, but most likely reason #4). Clearly, these were mostly motivated by anti-piracy concerns.
We have also seen a few revisions to the Broadway and Hollywood chips. The oldest photo I can find online of these chips is this one, dated November 17, 2006:
Note that this is the first revision of each chip — called simply “Broadway” and “Hollywood”. Protip: We can tell that the Hollywood chip was made in the 32nd week of 2006 (“0632”) and the Broadway chip was made in the 31st week (“0631”) — so, August or so.
Unfortunately, not many people share my same sick fascination with taking their expensive consoles apart and photographing them, so it’s hard to find photos of a wide range of chips online. On the Korean Wii I bought, it had a “Hollywood AA” (date code 0812) and a “Broadway B” (0744). I assume that there was a “Hollywood A”; if anyone has one of these, please send me a photo or at least give me the date code from the chip so I can build a proper timeline. (I also have a “Hollywood AA” (0801) with a “Broadway A” (0747)), and a “Hollywood” (0636) with a “Broadway A” (0641).
The chip differences aren’t really very meaningful to us. All of the chips have to run the same code. It’s likely that the revisions were done to fix minor glitches; for example, there are a few places in IOS where it checks to see if the Hollywood chip is older than some version, and if so, executes some additional code (redundant memory writes, presumably to work around a bug in the silicon).
Much more interesting to me are the PCB changes. The first couple of years of the Wii saw only one PCB, “C/RVL-CPU-01”; within the past year, there have apparently been two more (-20 and -30, as shown below):
Note that the major difference between -01 and -20 seems to be that there are a few missing parts. Segher says that this is probably simplified power-supply circuitry; this will be important later. Leaving these parts off may have allowed them to save an extra dollar or so; I can’t think of much other reason for the change. It’s also important to note that neither the Hollywood or Broadway seem to have changed — they are still at Hollywood AA and Broadway B.
The -30 PCB is what has me stumped. This photo came from someone on IRC who bought a new (“unsoftmoddable”) Wii in Australia; he sent it to me as part of our efforts to debug the HackMii Installer. The only difference between those two is … the Broadway chip package is much, much smaller. I’m told that it’s not likely that they actually shrunk the die; rather, they probably just shrunk the metal package, and placed the balls of the BGA package closer together. Unfortunately, I can’t read the writing on the Broadway chip in this photo; if anyone has a Wii with a small chip like that, please take me some pictures of the top and bottom of the PCB!
My theory is that the switch from -01 to -20 coincided with the switch from boot2v3 to boot2v4, and that is when we started seeing reports of “unsoftmoddable Wiis”. I’ll cover the software aspects of this in a separate post.