We discuss the implementation of a time-division SQUID multiplexing system for the instrumentation of large-format transition-edge sensors (TES) arrays. We cover the design and integration of cryogenic SQUID multiplexers and amplifiers, signal management and wiring, analog interface electronics, a digital feedback system, serial-data streaming and management, and system configuration and control. We present data-verifying performance of the digital-feedback system. System noise and bandwidth measurements demonstrate the feasibility of adapting this technology for a broad base of applications, including x-ray materials analysis, and imaging arrays for future astronomy missions such as Constellation-X (x-ray) and the SCUBA-2 instrument (submillimeter) for the James Clerk Maxwell Telescope.