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. 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 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.