RCA 301 Programmer's Reference Manual page 25

The magazines are removable and interchangeable, and they may be removed from one retrieval unit, inserted
and processed on other 3488 retrieval units.
A card is removed from its magazine by mechanical grips which are program addressable. Once the card enters
onto the transport belts (see figure 2) it moves towards the read/write heads located near a revolving drum (capstan)
where data can be read or recorded.
A gate located at this point determines whether the card is to be returned to the magazine where it came from,
or to remain at the recording station and be circulated under the read/write heads.
Retrieval Assembly
Each eight-magazine Retrieval Assembly (3488-1) contains, in addition to the magazines, a card transport
mechanism, card selection mechanism, read/write station, and all necessary internal addressing and timing logic. The
Expansion Assembly (3488-2) can expand the capacity of the unit to 16 magazines. The Expansion Assembly
contains a card transport mechanism and a card selection mechanism.
Magazines
Each magazine contains two decks of 128 uniquely addressed cards. Each deck of cards is contained within
a separately-addressable half of a magazine. Addressing is independent of the relative position of the cards within
each half-magazine. This eliminates the need for a card to be returned to the exact same position within its deck; it
is returned to the end of the deck in the half-magazine from which it was extracted.
Card Transport Mechanism
This Transport (Raceway) mechanism provides the means for physically moving the selected card to the
read/write station (card feed) and returning the card to the magazine (card return). If the expansion assembly is
added, the expansion assembly transport mechanism feeds into the primary card transport mechanism for movement
to and from the read/write station.
RCA Computer System with Maximum 3488 Configuration
Four 16-Magazine Retrieval Units
5.4 Billion Characters
RCA 301
Four 16-Magazine Retrieval Units
Figure 1
II-9