0x00EE) {
			// return
			this.pc = this.r.pop();
			return;
		}
		if ((op & 0xF0FF) == 0xE09E) {
			// if -key
			if (Object.keys(keymap[this.v[x]]||{}).some(x => x in this.keys)) { this.skip(); }
			return;
		}
		if ((op & 0xF0FF) == 0xE0A1) {
			// if key
			if (!Object.keys(keymap[this.v[x]]||{}).some(x => x in this.keys)) { this.skip(); }
			return;
		}
		if ((op & 0xFFF0) == 0x00C0) {
			// scroll down n pixels
			var rowSize = this.hires ? 128 : 64;
			for(var layer = 0; layer < 2; layer++) {
				if 