The ASCII16-X Mapper Extra Large (XL) 8 MB for MSX is an extension to the common ASCII16 mapper. It provides extended memory capacity, FlashROM memory which allows for persisting save games, mirroring of pages and bank select registers across the entire address space, and is backwards compatible with existing software.

Project page: ASCII-X FlashROM cartridge

The primary goal of this project is to provide the MSX community with open hardware implementations of ASCII mappers with these extended capabilities, using only commonly available parts, and aimed at optimising manufacturing simplicity and cost. As such, this project also contains actual cartridge hardware implementations built with plain logic ICs.

This design is made with KiCad 9.0.2. Its dimensions target the Overrich cartridge cases. Board width is kept under 10 cm to allow for cheap PCB fabrication. The surface mount components are also all on a single side for cheaper PCB assembly, as well as simplified hand-soldering using a stencil.