They still make bus systems similar to S-100. VME was a successor, and I use VPX which has PCI Express (or any switched fabric if you're ambitious enough) on t

They still make bus systems similar to S-100. VME was a successor, and I use VPX which has PCI Express (or any switched fabric if you're ambitious enough) on the backplane, at my day job every day. https://en.wikipedia.org/wiki/VPX https://en.wikipedia.org/wiki/VPX I wish VPX was more widely-adopted. You can get processor modules, the modules can have XMC mezzanine cards for add-ins like GPUs and NVMe drives, 10-gig (and faster) networking (including switches and routers) over the backplane, RAID storage arrays, FPGA modules, and more all in a rugged chassis. You can get compact 3U boards and can make NUC-sized systems, or use the full-sized 6U boards and go nuts cramming capability into a printer-sized boxes. But because it is almost exclusively limited to the aerospace/military domain everything is obscenely expensive. A cheaper, less rugged, consumer-focused version could transform computing: easy tool-less upgrades, no clearance/compatibility issues with GPUs, cable-less desktops, and extreme modularity. You could have an 8-bay chassis the size of a NAS from Synology or QNAP with 8 slots, with 2 for CPU, 2 for GPU (or 1 each for low-power devices), 1 for storage, 1 for advanced pro audio, 1 for video capture, and 1 with a bunch of M.2 slots for massive storage arrays. Need to upgrade your gpu? Just pull a handle and slide it out, and slide the new one in. One can dream!