How MAME Works
From MAMEDEV Wiki
The following is a list of documents describing the internal workings (core) of the MAME emulator. Most are penned by Aaron Giles.
Filters and streams in the MAME Sound System
MAME Interrupt Function Review
Executing Code Out of an Area With a Read Handler
Layouts and Rendering for MAME Artwork System
Writing Messages to the Screen In a MAME Driver
Programmable Logic Devices in MAME