From the Defender February 1981 Manual, 16P-3001-101

CPU/Video Board
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Requires Decoder ROM 2 at location 3K and Decoder ROM 3 at location 3E.

C8573 Interface Board
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Jumper W1 must be installed. W2 must be removed.

Rom Board - D8520
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For Blue Label roms, insert the following jumpers:
W2, W3, W6, W7,
W10, W11, W13, W16,
W17, W20, W21,
W24.

Note: ROM 4 is not used.

** Between blue and green-labeled ROM sets, ROMs 2,6,7,8,9,10,11 and 12 are COMPATIBLE.