Documentation Wanted

Chip name	Maker/Brand	System / driver	Priority	Notes
DP8534-V	National Semiconductor	Second-generation 68040 Macs (Quadra and Centris 610/650/800)	Low	I was able to reverse-engineer enough of this chip from a Linux driver to create a usable emulation (thanks smf!) but some details are still unclear.
F8680 PC/CHIP	Chips and Technologies	Cablenet 2039 Controller	Low	Enhanced 8086 CPU with PC-like on-chip peripherals and one or two custom instructions. Some documentation is online, but Programmer's Reference Manual (UG75) is missing.
HPC family (e.g. HPC46003)	National Semiconductor	Various ISA/MCA storage controllers, AGE crane games	Low	The most detailed architectural reference, the HPC16083/HPC16043/HPC16003 User's Manual (424410897-001A), is unavailable, though datasheets and application notes are easy to find. The HPC46400E User's Manual (420420213-001), though for an uncommon later model, may also be of interest here.
i750 Video Processor (82750PB + 82750DB)	Intel	Dragon Gun	Not so low	The Intel 82750PB Microcode Programming Guide is of particular interest.
M16 series (M31000, M31002, M31010, M31011)	Mitsubishi	Korg Trinity	Low	32-bit CISC architecture related to M32. Likely discontinued before the Renesas takeover in favor of M16C and M32C, whose CPU cores are completely different. https://github.com/linuxha/asl/ supports its assembly language.
MN1600 series (MN1610, MN1611, MN1613, MN1617)	Panasonic	Fujitsu/Panafacom/Matsushita FACOM 9450, C-15/C-x80 and Operate xxx series	Low	http://www.st.rim.or.jp/~nkomatsu/panafacom/MN1610.html has a lot of info but isn't complete, especially for the MN1617.
MN1860 series (e.g. MN1860003)	Panasonic	CD-ROM drives	Low	Upgrade of MN1880. Selection guide summarizes features of a few models. Instruction set mostly deduced from reverse engineering.
MN1880 series (e.g. MN18801A, MN1880023, MN1884820)	Panasonic	Novation synthesizers, Yamaha PSR-500, various CD-ROM drives	Low	Selection guide summarizes features of a few models. Instruction set mostly deduced from MN1872423 (MN1870 series) documentation and reverse engineering, but most internal registers remain mysteries. A manual for CL/1, a C-like compiled language developed by Panasonic for MN1880 and other MCUs, would also be potentially of interest.
PPC1, PPC2	Paradise Systems (later Western Digital)	Sun 3/80, Schneider Tower AT 220, various Paradise/WD ISA video cards	Low	These are single-chip versions of the IBM PC parallel port interface (PPC2 adds bidirectional capability). They probably work similarly to other parallel port controllers, but datasheets are not available.
SPC900/SPC970 series	Sony	MechaCon in older PlayStation 2 models	Low	Very little is known about this 16-bit MCU architecture beyond some not very informative datasheets.