MAME LUA/Debugger Question

[VooDooUdo2]

I'm trying to develop a LUA script to take action based on a memory address in a game. Specifically, Area 51, and I'm looking at the ammunition count. I've determined this lives in the maincpu program space at address 0x9000876F. If I run the debugger, start a game, then run the debug command print maincpu.pb@9000876F it outputs 8, which is what I expect. In my LUA script I'm trying to access this via manager.machine.devices[":maincpu"].spaces["program"]:read_u8(0x9000876F)), but it always returns 0, and I'm racking my brain trying to figure out what I'm doing wrong. I am new to programming in MAME, so I'm sure it's something simple, any help would be much appreciated!

[Tafoid]

I'm trying to develop a LUA script to take action based on a memory address in a game. Specifically, Area 51, and I'm looking at the ammunition count. I've determined this lives in the maincpu program space at address 0x9000876F. If I run the debugger, start a game, then run the debug command print maincpu.pb@9000876F it outputs 8, which is what I expect. In my LUA script I'm trying to access this via manager.machine.devices[":maincpu"].spaces["program"]:read_u8(0x9000876F)), but it always returns 0, and I'm racking my brain trying to figure out what I'm doing wrong. I am new to programming in MAME, so I'm sure it's something simple, any help would be much appreciated!

While I can't help you directly, there is a rather lengthy documentation file (as well as the files provided with MAME) which can act as a guide:
https://docs.mamedev.org/luascript/index.html

Hope this helps.