Subject: Re: [stella] Strange RIOT(?) register writes in Star Ship?!? From: Glenn Saunders <cybpunks2@xxxxxxxxxxxxx> Date: Thu, 29 Aug 2002 22:56:41 -0700 |
There are three unused bits in SWCHB. If you set these to output you can read back whatever you write to SWCHB. So you could consider them as three bits more RAM, if you will. In the upper example it seems that the state of "gameOffBool" is stored in bit D4 of SWCHB. I suppose it's used to check if the game is off at the same time as the RESET or SELECT switches are checked.
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