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Adds various notes to self.
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@ -59,6 +59,21 @@ class ConcreteMachine:
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// TODO: the entirety of dealing with this cycle.
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/*
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Normal memory map:
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000000: RAM
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400000: ROM
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9FFFF8+: SCC read operations
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BFFFF8+: SCC write operations
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DFE1FF+: IWM
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EFE1FE+: VIA
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Overlay mode:
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ROM replaces RAM at 00000, while also being at 400000
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*/
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return HalfCycles(0);
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}
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@ -69,6 +84,30 @@ class ConcreteMachine:
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private:
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class VIAPortHandler: public MOS::MOS6522::PortHandler {
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void set_port_output(MOS::MOS6522::Port port, uint8_t value, uint8_t direction_mask) {
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/*
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Port A:
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b7: [input] SCC wait/request (/W/REQA and /W/REQB wired together for a logical OR)
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b6: 0 = alternate screen buffer, 1 = main screen buffer
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b5: floppy disk SEL state control (upper/lower head "among other things")
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b4: 1 = use ROM overlay memory map, 0 = use ordinary memory map
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b3: 0 = use alternate sound buffer, 1 = use ordinary sound buffer
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b2–b0: audio output volume
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Port B:
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b7: 0 = sound enabled, 1 = sound disabled
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b6: [input] 0 = video beam in visible portion of line, 1 = outside
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b5: [input] mouse y2
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b4: [input] mouse x2
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b3: [input] 0 = mouse button down, 1 = up
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b2: 0 = real-time clock enabled, 1 = disabled
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b1: clock's data-clock line
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b0: clock's serial data line
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Peripheral lines: keyboard data, interrupt configuration.
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(See p176 [/215])
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*/
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}
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};
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