Friday 6 October 2017

Hardware Interface

I've been working on more general interface code. You can see it running here.

The first two pages 0x and 1x are the 'on LEDs' - only one at 08/18 at 4,B which is 4 across, 4 down. 0D/1D and 0E/1E are set up to access LEDs (E and F values) and re displaying digits 60 (2D/2E)

New stuff includes the game ID, which is at 2C at the moment ; this is the 'cartridge selector' connections which are currently %0101 or 5.

The keyboard scanner also works - this is at 20-24. Bit 3 of $20 being set means the left key is being pressed, Bit 2 of $21 means that the 'Number of Players' key (P) is being pressed. If fire was being pressed bit 0 of $22 would be set.

There is also code to clear the screen and the whole of memory.

I'm going to have 2 players by having the 'current player information' in $30-$3F, and switching this with another bank, $40-$4F maybe,  each time the player changes sides. Additionally the difficulty level will be primarily speed based. With a bit of luck all this will be automatic.

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