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Software update of a arcade pcb?

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Steelflight

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Hi,

i got a arcade board (pretty soldier sailor moon) that has different software revisions releases.
There was a version 21, 22 and 22B with short time in between. Dont think any hardware was changed.
I wonder if this is only bios related stuff?
So, can i just burn another bios chip with newer version and done? Or does it need more than that, like complete new romset?
Im new on arcade stuff so sorry if my question sounds stupid idea..

regards
Chris
 
That PCB is pretty valuable, so be careful with what you do. In order to just change the software release, you just would need to change the program ROM, which I believe is just one eprom. Remove the original, DO NOT rewrite on the original as that would be a repro-crime and get a new eprom with the new program. Plug it in and give it a go. While you are at it, double check that your program rom is dumped and preserved in MAME.

https://github.com/mamedev/mame/blob/master/src/mame/atlus/cave.cpp#L4838
 
there two eproms, one U45 near the CPU, and U9 near the SPU. I think i have to switch only U45?
And yes i will not overwrite stuff, plan is test the version difference. If it is just so easy ..
 
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According to MAME is U45 and U46, the ones containing the main program. Careful! Notice that the region is dictated by another EEPROM small chip, so whatever you write in the eproms, the region will be the same.
 
I have the HK 21 board.
I was searching for the difference of each versions.
But only thing i have found are some bug fixes, Boss fights day after final release version.
 
Thanks, I would burn 2 new ROMs and get version 22B at least. It will still be Hong Kong, but you will have the latest version.
 
i did some research and collecting the roms.

so as darksoft say U45 and u46 is holding the main programm for the cpu:

ROM_REGION( 0x400000, "maincpu", 0 ) \
ROM_LOAD16_WORD_SWAP( "bpsm945a.u45", 0x000000, 0x080000, CRC(898c9515) SHA1(0fe8d7f13f5cfe2f6e79a0a21b2e8e7e70e65c4b) ) \
ROM_LOAD16_WORD_SWAP( "bpsm.u46", 0x200000, 0x200000, CRC(32084e80) SHA1(0ac503190d95009620b5ad7e7e0e63324f6fa4eb) ) \

But only U45 is a eprom with 512kb. The other Eprom is U9 for the SPU:

ROM_REGION( 0x80000, "audiocpu", 0 ) \
ROM_LOAD( "bpsm945a.u9", 0x00000, 0x80000, CRC(438de548) SHA1(81a0ca1cd662e2017aa980da162d39cfd0a19f14) ) \

So i think i just need U45/u9 after all? Otherwise it make not really sense why U46 is not a eprom? Correct me if im wrong :)

shk.jpg
 
U46 is a Mask Rom, that's an Eprom that is made in Factory, you can't reprogram it. Best you can do is desolder (being super careful) and put a socket there and replace with a compatible Eprom. In your case, looking at MAME, you only need to change U45, which is already a socketed Eprom.
 
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