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Multiface II

7 bytes added, 17:42, 11 August 2006
/* How did it work? */ VGA>Gate Array
Needless to say, the Multiface did just that (except written in machine code). If I could get £40 for that one line of program, I’d be smiling.
But that only records what’s in memory. The CPC also has a barrage of dedicated chips to control the display (the [[CRTC]]), colours and memory configuration (the [[VGAGate Array]]), sound and the keyboard (the [[PSG]]), and so on. There is no equivalent of the PEEK command for these chips. So how do you find out what the settings are – what colours are in use, what size and mode the screen is in, and so on?
It works like this. The CPC sends instructions to these chips using the OUT command. Each chip has a different address. So you can send the value 1 to the CRTC with the command OUT &BC00,1; you can send the same value to the VGA with the command OUT &7F00,1; and so on.