Made an attempt at hooking up the '2' and '4' keys. A mostly unsuccessful attempt. 2 does nothing, 4 clears the screen.

Machines/Vic-20/Vic20.hpp

@@ -22,10 +22,47 @@ enum ROMSlot {
 	ROMSlotCharacters,
 };
 
+
+#define key(line, mask) (((mask) << 3) | (line))
+
+enum Key: uint16_t {
+	Key2	= key(7, 0x80),		Key4	= key(7, 0x40)
+};
+
 class UserPortVIA: public MOS::MOS6522<UserPortVIA> {
 };
 
 class KeyboardVIA: public MOS::MOS6522<KeyboardVIA> {
+	public:
+		void set_key_state(Key key, bool isPressed) {
+			if(isPressed)
+				_columns[key & 0x07] &= ~(key >> 3);
+			else
+				_columns[key & 0x07] |= (key >> 3);
+		}
+
+		// to satisfy MOS::MOS6522
+		uint8_t get_port_input(int port) {
+			if(!port) {
+				uint8_t result = 0xff;
+				for(int c = 0; c < 8; c++)
+				{
+					if(!(_activation_mask&(1 << c))) result &= _columns[c];
+				}
+				return result;
+			}
+
+			return 0xff;
+		}
+
+		void set_port_output(int port, uint8_t value) {
+			if(port) _activation_mask = value;
+		}
+
+		KeyboardVIA() : _columns{0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff} {}
+	private:
+		uint8_t _columns[8];
+		uint8_t _activation_mask;
 };
 
 class Machine: public CPU6502::Processor<Machine>, public CRTMachine::Machine, public MOS::MOS6522Delegate {
@@ -34,6 +71,7 @@ class Machine: public CPU6502::Processor<Machine>, public CRTMachine::Machine, p
 
 		void set_rom(ROMSlot slot, size_t length, const uint8_t *data);
 		void add_prg(size_t length, const uint8_t *data);
+		void set_key_state(Key key, bool isPressed) { _keyboardVIA->set_key_state(key, isPressed); }
 
 		// to satisfy CPU6502::Processor
 		unsigned int perform_bus_operation(CPU6502::BusOperation operation, uint16_t address, uint8_t *value);

OSBindings/Mac/Clock Signal/Wrappers/CSElectron.h

@@ -6,8 +6,7 @@
 //  Copyright © 2016 Thomas Harte. All rights reserved.
 //
 
-#include "CSMachine.h"
+#import "CSMachine.h"
-#import "KeyCodes.h"
 #import "CSKeyboardMachine.h"
 
 @interface CSElectron : CSMachine <CSKeyboardMachine>

OSBindings/Mac/Clock Signal/Wrappers/CSKeyboardMachine.h

@@ -6,6 +6,8 @@
 //  Copyright © 2016 Thomas Harte. All rights reserved.
 //
 
+#import "KeyCodes.h"
+
 @protocol CSKeyboardMachine <NSObject>
 
 - (void)setKey:(uint16_t)key isPressed:(BOOL)isPressed;

OSBindings/Mac/Clock Signal/Wrappers/CSVic20.mm

@@ -39,6 +39,13 @@
 }
 
 - (void)setKey:(uint16_t)key isPressed:(BOOL)isPressed {
+	@synchronized(self) {
+		switch(key)
+		{
+			case VK_ANSI_2:		_vic20.set_key_state(Vic20::Key::Key2, isPressed);	break;
+			case VK_ANSI_4:		_vic20.set_key_state(Vic20::Key::Key4, isPressed);	break;
+		}
+	}
 }
 
 - (void)clearAllKeys {