Tap your card on a transit gate, drive through an electronic toll lane, or scan a warehouse pallet, and you are using a technology whose first patent was granted more than fifty years ago. In 1973, an engineer named Mario Cardullo received what is widely cited as the first US patent for an RFID tag with rewritable memory. It held a grand total of sixteen bits, and it was built to collect highway tolls. That tiny transponder is the direct ancestor of nearly every connected device that senses, identifies, or tracks something in the physical world today.
A 16-bit tag powered by the reader
Cardullo's device, covered by US Patent 3,713,148 and granted on January 23, 1973, did something that still defines modern RFID and NFC: it carried no battery. A passive tag draws all the energy it needs from the radio signal of the interrogating reader. When the reader's field washes over the tag, that energy wakes up the circuit just long enough for it to transmit its stored data back.
The memory was sixteen bits of non-volatile storage, hand-built at the time from tiny ferrite cores because that was the only practical way to retain data without power. Sixteen bits is enough for 65,536 unique values, which was plenty to identify a vehicle at a toll plaza. The prototype was demonstrated in 1971 to the New York Port Authority and other potential users as exactly that: an automated toll device.
Why a half-century-old idea still matters for IoT
It is tempting to treat RFID history as a museum piece, but the engineering constraints Cardullo solved are the same ones every embedded systems team wrestles with today. Power, memory, and cost have always been the three walls of connected hardware design, and the passive, powered-by-the-reader trick is one of the most elegant answers anyone has found.
That same principle scaled into the contactless world we now take for granted. The access badge that opens your office door, the tap-to-pay chip in your card, the inventory tags on retail shelves, and the asset trackers moving through supply chains all inherit Cardullo's basic architecture. The frequencies, encoding, and standards have evolved, but the core bargain has not: keep the tag cheap and battery-free, and let the reader do the heavy lifting.
The lesson for builders today
The story is a useful reminder when you are scoping an IoT project. The most durable designs are usually the ones that respect their constraints instead of fighting them. A sixteen-bit toll tag sounds laughably small until you realize it did exactly one job perfectly and cheaply enough to deploy at scale. Plenty of modern connected-device projects fail not because the silicon is too weak but because the design tried to do too much per node instead of letting a well-chosen reader, gateway, or cloud layer carry the complexity.
In the Philippines and across Southeast Asia, RFID is everywhere from toll networks to retail and logistics, which makes it a natural starting point for teams building their first connected product or thesis prototype. Understanding why the original tag was designed the way it was helps you make better decisions about where to put memory, processing, and power in your own system.
If you are designing something that needs to identify, sense, or connect, the right architecture matters more than raw horsepower. Fluidwire builds IoT and web services from silicon to cloud, and we are happy to help you figure out where the smarts in your system should live. Get in touch to talk through your project.
