PCIe cards stores up to 4 billion samples on board

What is an oscilloscope?
Oscilloscopes are test instruments that display electronic signals (either waves or pulses) on a screen. It creates its own time base against which signals can be measured, and displayed frames can be frozen for visual inspection. It is sometimes abbreviated as CRO, for cathode-ray oscilloscope, or commonly called scope or O-scope.

What is PCIe?
"PCIe or PCI Express is a high-speed peripheral interconnect introduced by Intel Corp. in 2002. Initially used for high-speed display adapters, and eyed to eventually replace the PCI and AGP buses entirely, PCIe was designed to match the higher speeds of today's CPUs. "