The Sinclair QL shipped with 128kB of RAM, and almost everything worth running on it wants more. This board provides up to 768kB of additional fast static RAM on a small card that plugs into the QL's expansion slot.

A DIN41612 pass-through connector on the far edge means the slot isn't consumed — you can chain further interfaces behind it. A two-position DIP switch selects between four configurations: 640kB (the standard 512kB expansion), 832kB (leaves 64kB free for correctly configured expansion cards without touching the ROM cartridge area), 896kB (maximum RAM, no room left for other cards), and a special mode for use as a second expansion alongside an already-expanded QL.

The design is built around a single 1M×8 static RAM in TSOP-II-44 and a GAL16V8 handling all the address decoding. GALasm sources and JEDEC fuse maps for both GAL revisions are included, so you can program your own. It can also be stacked with the author's earlier 512kB MIX board, or paired with the QL MiniTrump3 disk interface to recreate the original Trump Card combination.

Board is 97.79 × 35.56 mm, two layers, with seven SMD parts and six through-hole — well within reach of hand assembly.

This is just sharing the project. All design work is by Alvaro Alea Fernandez and is published at https://github.com/alvaroalea/QL_RAM_Expansions under the CERN Open Hardware Licence v2 (Strongly Reciprocal). It builds on earlier work by McLeod Ideafix, Jose Leandro, Zerover and tcat, and on liont's QUBIDE clone. I have only reorganised the files and generated a BOM and centroid; please credit the original author.