From the Defender April 1981 Manual, 16P-3001-101 R-T CPU/Video Board --------------- Requires Decoder ROM 2 at location 3K and Decoder ROM 3 at location 3E. C8573 Interface Board --------------------- Jumper W1 must be installed. W2 must be installed. Rom Board - D8572 ----------------- For Red Label roms, insert the following jumpers: W2, W4, W6, W7, W9, W11, W13, W16, W17, W20, W21, W24 Note: ROM 5 is not used.