Collators The collator ... is a card device which will merge two sets of cards without disturbing their original sequence, and, in addi- tion, will select cards to be kept out of the merged sequence. Two hoppers and feed units (fig. 8-21), along with four or five pockets for stacking cards are provided.

The two feed units in the collator are called the PRIMARY FEED and the SECONDARY FEED. Cards placed in the primary feed hopper are referred to as primary cards, and those placed in the secondary feed hopper are called secondary cards. Cards are placed in the hoppers face down, with the 9 edge toward the throat.

Most collating operations require that two numbers be compared. For example, when checking sequence, the number coded on one card must be compared with the number on the preceding card to see if the cards are in the proper order. Also, when merging, the number coded on a card in one feed unit must be compared with the number on a card in the other feed unit to see which cards is to be fed first.

When one card is compared with another, one of three possible conditions may exist with regard to the number coded on the card; it may be lower than, equal to, or higher than the number on the other card. Card feeding and selection can be controlled by control panel wiring (not shown) when either of these conditions occurs.

Note from the illustration (fig. 8-21) that the primary cards pass two sets of brushes, while the secondary cards pass only one set. The readings from the two sets of brushes in the primary feed unit can be compared with each other, or with the readings from the secondary brushes. Since the secondary feed unit contains only one set of brushes, readings from the secondary brushes can normally be used only for comparing with readings from the primary brushes.

The Type 77 Electric Punched Card Collator performs many card filing and pulling operations. As a filing machine, the Collator feeds and compares simultaneously two groups of punched cards: records already in file, and records to be filed. These two groups are merged in correct numerical or alphabetical sequence. If desired, the machine will at the same time remove from either group, those cards which are matched by cards in the other group, or all but those cards which are matched, or other selected cards.

When operated for the purpose of pulling cards, the Collator makes it possible for one group of cards to pull corresponding cards from another group. The cards not pulled are segregated for return to the file, and the absence of any cards sought is indicated by segregation of the corresponding pulling cards. The cards pulled and those which pull them may be kept separate, or merged in sequence, as required.

Many operations, previously performed less efficiently, are made automatic by this machine. Following is a brief list of applications:

• Filing current transaction cards with previous transaction cards.
  
  
• Pulling accounts receivable debit cards and combining them with cash received credit cards.
  
  
• Replacing old record cards with new record cards superseding them.
  
  
• Selecting all cards dated earlier than a certain date, as for analysis of accounts in arrears, or all cards containing a given classification number, when cards are scattered throughout the file.
  
  
• Combining master cards, such as name and address and rate cards with transaction cards and separating them again after their use in accounting machine operations.