“The punch card was data processing back then”

Question

I find it difficult to understand the sentence as shown in the title.

1. Is the card data?
2. Is the card processing?
3. Is the card a method (or style) to process data?

I'm Chinese. If I express the sentence with Chinese I'll say The punch card was the main method of data processing back then.

---

NOTE: I'm a programmer and I know what a punch card is. So please don't waste you precious time to explain the punch card.

Answer 1

In this brief quote, the author Joe Celko is using a figure of speech, specifically syndecdoche, in his explanation of how the punched-card framework shaped data processing, from the turn of the century up until the early 1970's.

In syndecdoche, "part of something is used to refer to the whole thing". In this case the "part" is a punch card, and the "whole" encompasses punched-card data processing equipment and methods based on that kind of equipment.

Conceivably one could regard the figure of speech as an instance of metonymy, in which "a thing is called ... by the name of something intimately associated with that thing or concept." That is, "The punch card was data processing back then" may be seen as referring to all the keypunches, sorters, and other card-based unit record equipment and computers by reference to the pieces of paper they all processed.

Answer 2

Here's my interpretation:

In people's minds, data processing and punched cards were almost the same thing. If you had asked somebody "What is data processing?" they would have answered, "Data processing is what you do with punched cards."

Answer 3

The sentence sounds like something that may have been overheard during a verbal conversation, as @jwpat7 said, this sounds like a figure of speech.

It sounds as if the speaker is saying that the use of punch cards was for all intents and purposes the only way to do data processing during the time-period in question. Admittedly it's a bit tough to tell for sure without some additional context.

Answer 4

wikipedia A punched card, punch card, IBM card, or Hollerith card is a piece of stiff paper that contains digital information represented by the presence or absence of holes in predefined positions. Now an obsolete recording medium, punched cards were widely used throughout the 19th century for controlling textile looms and in the late 19th and early 20th century for operating fairground organs and related instruments. They were used through the 20th century in unit record machines for input, processing, and data storage. Early digital computers used punched cards, often prepared using keypunch machines, as the primary medium for input of both computer programs and data. Some voting machines use punched cards.

1 Yes, it stores data. 
2 Yes, it handles the data. 
3 Yes, definitely the punch card is method of dealing with data.

In short the sentence means that at that time they were using punch card to handle with data. So you are right saying The puch card was a main method of data processing back then .