I didn't decode the bits, but all three SPI pins show activity on the logic probe at boot, so I think your code is running. I can hook up the logic analyzer tomorrow and check the data you're sending, if you don't find the problem before then.
Good to know that there is some activity. Logic analyzer test would be neat - maybe it's revealing some obvious bug like wrong chipselect.
The OSD control register settings seem to match up with the OSD datasheet, and they are taken from the NSS BIOS anyways, so they should be working. Internal Clock is on, so it should work even if SNES PPU is disabled. The OSC1,OSC2 stuff is stopped - looks a bit suspect, but the NSS BIOS is always doing that, too.
One possible problem might be that the program is accessing the OSD chip too soon after reset. The datasheet is mentioning 'something' about 1ms on last page (not quite clear what that means, and how it fits to reset signals that might be generated by the NSS mainboard). Anyways, the OSD chip is re-initialized in each test screen - if you push some of the four joypad direction keys then the program should redo the OSD init far away from the reset signal.
There should be also some new activity visible on the OSD SPI bus when pushing joypad DPAD buttons, that might also help to see if the Z80 is running or crashed.
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Here are working PROM dumps for all 12 games:
http://nocash.emubase.de/nss-keys.zip - the 5 new keys (with zeroes in first bit) will be working in next no$sns update. Your two new dumps worked find, and for the remaining three games I already guessed the first 8 bytes from INST ROM, and the 9th is usually containing some checksum, so I could calculate the missing value, which worked, too - except for Contra 3, that's using a "wrong" checksum in 9th byte - but I got it deciphered with the brute-force program.
NB. Contra 3 is somewhat less than an experimental pre-prototype game, the INST ROM is almost empty, and even the main menu title string just says "New Game 1". There isn't anything contra-specific in INST ROM, and I think also nothing NSS-specific in the PRG ROM.
With the dumped font & the datasheet details about things like character sizes and the odd scrolling/wrapping feature, my OSD emulation is now looking much nicer. Many thanks there!