High-Speed I/O, PCIe 6.0/7.0, and CXL Memory Pooling: PAM4 Signaling, Flit Mode, DMA, Peer-to-Peer Transfers, CXL.mem/CXL.cache, and Disaggregated Memory Tiers

Deep End Era. Engineering with Sankalp · Oct 29, 2026 · 1h 6m

Every three years for two decades, PCI Express has doubled the speed of the copper traces connecting CPUs, GPUs, NVMe drives, and network cards—until at 64 gigatransfers per second, binary ones and zeros dissolved into heat inside the circuit board. We unpack PAM4 four-level signaling, low-latency FEC, 256-byte Flit mode, scatter-gather and Peer-to-Peer DMA, and CXL coherent memory pooling.

Chapters

00:00:00 Opening: Sixty-Four Billion Pulses a Second Across Twelve Inches of Copper

00:04:35 The Physics of the Copper Wall: Why Binary NRZ Signaling Died After PCIe 5.0

00:12:15 Four Voltage…