Fixed X register overflow

src/memory.c

@@ -57,7 +57,7 @@ void write6502(uint16_t address, uint8_t value){
 		case VIDADDRS ... VIDADDRS + PAGESIZE:
 			switch ((address - VIDADDRS) % 4){
 				case 0:			/* Video X Register */
-					videoX = value;
+					videoX = value & 0b01111111;
 					break;
 				case 1:			/* Video Y Register */
 					videoY = value;