 0x00FC) {
			// scroll left 4 pixels
			var rowSize = this.hires ? 128 : 64;
			for(var layer = 0; layer < 2; layer++) {
				if ((this.plane & (layer+1)) == 0) { continue; }
				for(var a = 0; a < this.p[layer].length; a += rowSize) {
					for(var b = 0; b < rowSize; b++) {
						this.p[layer][a + b] = (b < rowSize - 4) ? this.p[layer][a + b + 4] : 0;
					}
				}
			}
			return;
		}
		if (op == 0x00FD) {
			// exit
			this.halted = true;
			this.exitVector();
			return;
		}
		if (op == 0x00FE) {
			// lor