Thanks! Good finding!
I don't remember where I got the pinouts from - probably from this doc
http://www.romhacking.net/documents/%5B ... 110F0a.txt made by Kammedo.
Looking at SHVC-LDH3C-01 board photos (with RTC)... yeah, looks as if pin 80 and 81 wired to different supply voltage lines.
Oh, but wait! There's also a SHVC-BDH3B-01 board photo (without RTC)... and that has pin 80 wired differently (there's no visible connection on the photo, but it does probably connect to something underneath of the chip, maybe to VCC (?) so the pinout would be correct for that board).
Both boards are HiROM, if one has Pin80 wired to VCC, and the other to GND... then it might be related to presence/absence of the RTC chip... or to the used ROM sizes.
PS. No, don't convert fullsnes.htm from 80 column 20 lines plain ascii to 1136x640 pixel 145 Kbyte png format! That's abuse.