The HD63484 ACRTC model in src/chips/hd63484.{h,cpp} was written from the Hitachi
datasheet and User's Manual (see docs/sources.md) using the structure of MAME's
src/devices/video/hd63484.cpp as its basis. That file is distributed under the
BSD-3-Clause license, reproduced here as it requires:

Copyright (c) Angelo Salese, Sandro Ronco
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