Interesting solution to high score problem

[Mike26]

I don't know if any of you guys follow hackaday but i was reading and came accross this:

http://spritesmods.com/?art=twitter1943

basically, this guy devised a method for tapping into the volitile high score data and got it to read out over ethernet and automatically post the highscore data to twitter with some custom hardware/addons... he did this with a 1943 arcade pcb and custom add-on hardware.

So, how could I make the game save its scores to something non-volatile? I could ofcourse add an EEPROM somewhere in the Z80s address space and then hack the firmware to load and save the highscore table to that. This would probably work, but the hack then would be restricted to only this type of arcade machine. Making the thing do more ludicrous tricks, like tweeting the current highscore, would be almost impossible: the Z80 would have to talk over TCP/IP as well as run the game, not to mention the NIC I'd have to wire into the existing arcade PCB.

I decided to take an alternative route, which is to add another bus master to the existing Z80 bus. A little explanation may be in order: A CPU like the Z80 has a parallel bus to read and write bytes from and to it's peripherials. This bus consists of 16 lines carrying the 16-bit address to be accessed and 8 lines carrying the data that is read or written. Some more lines indicate what should happen with the data: /RD becomes active if the data should be read from the address, an active /WR means a byte should be written. The Z80 can do accesses to I/O-ports and memory: in the former case /IOREQ is active and in the latter /MREQ will be. Normally, the rest of the hardware will look at these signals plus the top few address lines to see if the access should go to ROM, RAM or something else.

crazy stuff like this makes me wonder what can be done to mvs/aes hardware... i know we have some serious geniuses on these forums and i think it's just a matter of gathering support. I know in the past we've talked about high-score data but this is amazing. any thoughts?