Hardware Docs

Documentation of the VMU and its various components

The following pages attempt to meticulously document everything that is currently known about the Visual Memory Unit's hardware.

Page	Contents
Technical Specifications	Hardware Overview
Memory Map	Overview of the VMU's various memory spaces
Addressing Modes	Listing and details of the LC86K's addressing modes
Instruction Set	Listing of all LC86K instructions/opcodes and their encoding
Special Function Registers	Listing and details on all known SFRs within the Potato
XRAM	LCD Framebuffer pixel layout + icon locations
BIOS	Builtin OS and public firmware calls located within ROM
Interrupts	Listing of interrupt service routines and their configuration registers
Filesystem	Layout and description of the 8-bit FAT filesystem stored within flash
File Formats	Layouts and descriptions of the various VMU-related file formats

Note

The source material for the information here came from the following places:

• Marcus Comstedt's original VMU reverse engineering and research
• Official Sanyo Hardware Docs
• Long-lost wisdom from around the web, recovered from WaybackMachine
• Discoveries made by Dmitry Grinberg during the development of uM23
• Commercial minigame analysis and disassembly for EVMU
• VMU BIOS disassembly analysis for EVMU
• jvsTSX's various test apps for register poking and EVMU research
• VMU Filesystem research undertaken with DC-SWAT for Dreamshell
• Rikki Gibson's findings working on DreamPotato

Warning

Although every effort has been made to ensure the complete documentation of every aspect of the VMU's hardware, some mysteries still remain. Attempts have been made to clearly disclose holes in our understanding within these pages.