Abstract: Data processing apparatus performs automatic hardware device identification and system setup in computer systems that have a Programmable Option Select (POS) feature, where the system includes multi-card adapters (adapters with attached daughter card(s)), and/or multi-card planar complexes (system boards with pluggable processor complexes and/or I/O risers). In particular, the apparatus uniquely identifies the aforementioned multi-card devices utilizing unique "combination type" POS IDs, where a combination type POS ID is a POS ID specifically preassigned to a combination of cards rather than to a single type of card. According to the invention, the unique combination type POS ID is partitioned across the combination of cards (for example, hardwired into each card). When the cards are combined, the partitioned ID is synthesized and becomes available to the system.