Knights of the Round CPS1 B+C boards:
Knights of the Round is a CPS1 title that has a suicide battery and we can see that the battery has been removed from the C board and that a typical de-suicide mod has already been correctly performed to run its Custom IC sans any volatile security registers.
Knights of the Round C board uses a CAPCOM B21 Custom IC and IOC1 & C632 PAL IC which are identical to those on Street Fighter II CE/Turbo which uses a stock non battery B21, so I can easily swap over the C board onto my Street Fighter II CE B board to quickly test it:
It appears to be working so we can move over to the B board:
By checking MAME I can confirm that this Knights of the Round is missing two audio data EPROM from IC sockets 18 and 19 as well as missing a program data EPROM from IC socket 23.
Since this boards jumpers are set to JEDEC I will need to program two 27C010 for the audio and a single 27C4096 to replace the missing EPROM:
Before I program anything I use my Top3000 universal programmer to dump the contents of the program EPROM at IC socket 22, which matches the CRC of the kr_22.7f binary file from the ETC/World/US version of Knights of the Round MAME ROM set and I also dump the contents of the 27c512 in IC Socket 9 which should be audio data but appears to be corrupt and mostly blank, likely from its EPROM window not being covered and long exposure to UV light.
I completely erase the 27c512 and using the appropriate files from the MAME knights.zip I program it and the two new 27c010 with the correct audio data. However, since the B21 no longer as the volatile security keys in its memory I have to source decrypted program ROM files for the game which along with a lot of other games can be found at The Dead Battery Society.
Thankfully Knights of the Round only requires PROG ROM 23 to be decrypted so I can leave PROG ROM 22 as it is. The only unfortunate thing is that there is only a decrypted file available for the US version of this game, so I can’t get the European version that is missing the “Winners don’t use drugs” screen.
I then insert these newly programed EPROM back into the B board:
I re-insert the C board that came with this B board and test it and the game now works:
However… during playback I start noticing graphical issues, which is most noticeably affecting health bars:
And white dots around text on the character select screen:
When I originally tested the C board on my Street Fighter II CE I didn’t bother to test past the intro screen, but when I placed it back onto it to re-test it and started playing it a little, I was finding that with this C board Street Fighter II CE was also displaying odd graphical issue such as black dots above health bars:
And messed up chain fence on the Spanish stage:
From this I know that the Knights of the Round C board is bad. Both the IOC1 & C632 PAL IC are testing good and the other IC on the board only deal with additional inputs from the kick harnesses, so the only cause of the issue can be the CAPCOM B21 Custom IC which can not easily be replaced…
Placing my Street Fighter II Turbo B21 C board (and the one I used for Ghouls and Ghosts that has no kick harness for the extra buttons required for Player 3 inputs) results in perfect playback with no graphical issues:
So for now I have a broken C board that sort of almost works but since I have two spare compatible C boards I can swap them over for the moment when I wish to play Knights of the Round.
Not quite the result I had hoped for but good enough and the Ferrite Beads I had required for the B board that became Ghouls & Ghosts were donated from this C board so not a total loss.