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Restoring my Grail - Nintendo Upright R-Type

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myPinballs View Drop Down

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Post Options Post Options   Thanks (0) Thanks(0)   Quote myPinballs Quote  Post ReplyReply Direct Link To This Post Posted: 13 Jan 2018 at 12:23pm
Originally posted by John Bennett John Bennett wrote:

I'm far from an expert, but I think the work RAM is the two 64kBit SRAMS at 1F and 3F (one the lower 8, the other the upper 8 bits).
I've no idea how highscore mods work, but I can't think how it'd work if you keep the entire work RAM alive. A reboot would make the program go through the blanking operation to put it back to defaults, so you'd have to mod the program code to avoid wiping it. RAM tests would muck on with it too.
Maybe you could add an NVRAM device to the bus (modifying PALs and tapping into traces), then hack the ROM to point to this for high score data...
Just all seems rather unobvious to my untrained eye

Yeah i'm pretty convinced its rams 1F & 3F on the rom daughter board now. A 16 bit data bus. The main issue seems to be the ram test that's going to write garbage into them at power on before the program resets them with the defaults. I have ideas of creating some extra hardware to load scores from a separate location instead of roms as i know the address to be loaded and then mirroring the regular ram update if new high scores get added.

However, at the moment the easiest way is just to use my new rom editing tools and change the defaults to include my own top score. I am only bothered about the top score i have as this is the one shown on the attract screens and its unlikely to change very often, so for now i may well just create some custom roms.
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