programs have to be loaded into a computer’s memory
is not magic, is computer science
the need to program machines existed way before the development of computers
- e.g. textile manufacturing - if you just wanted to weave a big red tablecloth, you could simply feed red thread into a loom and let it run - but what if you wanted the cloth to have a pattern or plaid? workers would have to periodically reconfigure the loom as dictated by the pattern, which was labor-intensive and made patterned fabrics expensive

Jacquards Loom

in response, Joseph Marie Jacquard Loom developed a programmable textile loom first demonstrated in 1801 - the pattern for each row of the cloth was defined by a punched card, and the presence or absence of a hole in the card determined if a specific threat was held high or low in the loom such that the cross thread called the weft passed above or below the thread - to vary the pattern across rows these punch cards were arranged in long chains, forming a sequence of commands for the loom - familiar right?
many consider this loom to be the earliest form of programming

Tabulating machines

punched cards turned out to be a cheap, reliable and fairly-human-readable way to store data
a century later, punched cards were used to help tabulate the 1890 U.S. census
- each card held an individual’s person’s data like race, marital status etc.
- for each demographic question, a census worker would punch out a hole of the appropriate position
- when a card was fed into the tabulating machine, a hole would cause the running total for that specific answer to be increased by one
- in this way, you could feed the entire country’s worth of people and at the end, you’d have running totals for all of the questions that you asked
- they weren’t early computers as they could only tabulate - operation fixed and not programmable
- punched cards stored data, but not a program

over the next 60 years, these business machines grew in capability, adding features to subtract, multiply, divide, and make simple decisions about when to perform certain operations
to trigger these operations programmers accessed a control panel

full of little sockets, into which a program would plug cables to pass values and signals between different parts of the machine - that’s why they were also called plug boards
but this meant having to rewire the machine each time a different program needed to be run, so by the 1920s these plug boards were made swappable but still were fiendishly complicated to program
this style of plug board programming the world’s first general-purpose electronic computer, Eniac, 1946, used a ton of them
- even after a program had been completely figured out on paper, physically wiring up the Eniac and getting the program to run could take upwards of three weeks

given the enormous cost of these early computers, weeks of downtime simply to switch programs was unacceptable and the new, faster, more flexible way to program machines was badly needed
by the late 1940s and into the 50s, electronic memory was becoming feasible