High-channel-count, high-precision, and high-throughput time-to-digital converters (TDC) are needed to support detector arrays used in deep-space optical communications (DSOC) link receivers being developed between Earth and deep-space solar-system exploration platforms for human and robotic activities in 2020 and beyond. Compared to current radio-frequency (RF) space communications, DSOC will provide 10- to 100-times more data returns for future advanced instruments, live high-definition video, telepresence, and human exploration beyond cislunar space. To be accepted operationally, the optical link must provide substantially greater data rates/data-return volumes than equivalent mass and power RF systems — and at lower cost per bit. Therefore, to prepare for these deep-space missions, substantial enhancement of the current NASA telecom-link capacity is needed. To satisfy NASA's DSOC needs, a scalable high-precision (≤ 100 ps), high-throughput (> 100 Gbps) high-channel-count (≥ 256) time-to-digital advanced processor (HiTAP) architecture will be developed for use in single-photon-counting free-space optical communications systems and test beds. In Phase II, two fully functional systems integrating custom hardware, firmware, and software will be designed, fabricated, tested, and delivered to NASA.