[weblacky]

I'm not a SUN user, nor have direction knowledge...but I'm good at GOOGLE:
...
PROM password for your station isn't stored in PROM OR NVRAM

Be careful of equivocations. The boot code of a computer is sometimes called its "PROM", especially in the SGI world. Sun just called it OpenBoot and most PCs call it "BIOS" or "UEFI".
A PROM device is a specific type of IC (bipolar, non-erasable, and very fast). The boot code "PROM" is not necessarily (in fact almost certainly not) in a PROM!
By the 1980s, EPROM technology was rapidly developing and would be used for almost all firmware storage. In the 1990s this mostly switched over to Flash which is a dense type of EEPROM.
This mostly happened in parallel with a switch from large DIP packages to smaller PLCC and TSOP packages for firmware chips, but some designs held over. For example, the Indigo2 and Indy both use large, DIP40 EPROM chips for firmware, but the SparcStation 5 uses a PLCC32 Flash chip.

The boot parameters are something quite different and are stored in a different location (it wasn't until the 2000s that Flash chips with internal parameter storage were available). Both EEPROM (byte-by-byte erasable, reprogrammable storage) and NVRAM (SRAM with battery backup power) were used to store settings, and computer vendors mixed up the terminology a lot.

The page you quoted from is hopelessly confused on this point. The author appears to believe that he is removing the "PROM" chip but doesn't know what that means.

Uh...I'm really unsure what this above statement was, I don't read anything the way you're presenting it.  The two do not link up in my mind...so I'll restate the intent as it was unclear.

The author of the page I linked to claims to REMOVE THE SYSTEM PASSWORD.  That may be the REAL complaint of the post.  It seemed like the original post was trying to replace this chip get get around the password protection.  The info I researched (not that linked page) claims that won't work and SUN originally designed the protection to have to call them with dumped values to give you a reset code. Blanking the NVRAM or the changing the PROM will not get around the system firmware password protection...period...it's documented.

The above link claims this hack can be used to end-run the protection to reset the password system.  If you can reset or disable the password...then the original reason to replace the chip might not be relevant anymore.

The original post never claimed the chip was missing...only that they tried a replacement.  So my post was pointing out that...if you solve the password protection, perhaps the intent of the replacement is voided.  So then they can use the original chip.

This is why I asked if they even had the original chip...because it was unclear.

My link MIGHT solve problem #2...which might resolve problem #1.