Sinclair QL for MEGA65 (QL4M65)

A port of the Sinclair QL to the MEGA65, built on top of the MiSTer2MEGA65 (M2M) framework and based on the MiSTer-devel/QL_MiSTer core (68008/fx68k CPU, zx8301 video ULA, zx8302 I/O ULA).

Current status: Milestone 1 complete. The QL boots end-to-end on real MEGA65 R6 hardware: RAM check, boot logo, F1-F4 screen, 10-second timeout (or F1/F2/F5 response), and into SuperBASIC with a working keyboard - both Minerva and MGE tested. System ROM loads either automatically from a fixed SD card path at boot or manually via the Shell's Options menu, with the core auto-resetting itself after any manual ROM change. See .research/PORTING-PLAN.md and DECISIONES.md (in the parent directory) for the full, detailed log of the whole investigation and every decision made along the way.

Milestone 1 scope

• Native QL CPU speed (no QL/16MHz/24MHz/Full speed switch yet)
• PAL video only
• 128 KB RAM (implemented in FPGA BRAM for now; HyperRAM planned for a later milestone)
• System ROM: Main ROM (48 KB - Minerva, MGE, JS...) and Back ROM (16 KB - TK2, Pascal...) as two independent, fixed-size slots. Each auto-loads at boot from a fixed SD card path (/ql4m65/main.rom / /ql4m65/back.rom, both optional) and can also be changed at any time via the Shell's Options menu ("Main ROM:%s" / "Back ROM:%s" / "Extract Back ROM" to clear the Back ROM slot) - the core resets itself automatically after any manual change, no hard reset needed.
• Keyboard: MEGA65 keys mapped to the QL's matrix (replacing the real hardware's Intel 8049 IPC microcontroller with a real emulated one running the real community-patched firmware, ipc.vhd), using a deliberately MEGA65-native symbol layout - whatever's silkscreened on a MEGA65 key is what it types on the QL, not necessarily what the real Sinclair QL keyboard has in that position. Full key-by-key rationale in .research/keyboard-mapping-design.md.

Not yet in scope for Milestone 1: microdrive (.MDV, planned as Milestone 2), QL-SD (QXL.WIN), memory/CPU-speed expansion, mouse, or GoldCard/SMSQ,E support - these are planned for later milestones (see .research/PORTING-PLAN.md section 7 for the current milestone order).

Getting the compiled core

This repository is source only - no compiled .cor file and no system ROM (Minerva/MGE/JS are copyrighted Sinclair/AMS software, not redistributable here). A ready-to-use Milestone 1 .cor for MEGA65 R6 is available in the MEGA65 community on Discord

• ask there if you'd like a copy. Building it yourself from source requires your own copy of a QL system ROM placed on the SD card (see Milestone 1 scope above).

Repository layout

• CORE/vhdl/ - the actual QL4M65 port (clock generation, memory map, video/ keyboard wiring, Shell configuration)
• CORE/QL_MiSTer/ - git submodule, the MiSTer QL core (mostly unmodified; see doc/m2m/exceptions.md for the handful of deliberate changes and why)
• M2M/ - the MiSTer2MEGA65 framework itself (not modified)
• .research/PORTING-PLAN.md - the porting dossier and hardware-test log (every tested build, what changed, what happened)
• DECISIONES.md (parent directory) - chronological log of every technical decision and diagnosis made during this port, in Spanish

Credits

• QL4M65 port by Jose Daniel Fernandez Santos (dfsantos)
• MiSTer2MEGA65 framework by sy2002 and MJoergen
• MiSTer-devel/QL_MiSTer core by the MiSTer QL community

Licensed under GPL v3.

---

Built on the MiSTer2MEGA65 framework - learn more about M2M itself via The Ultimate MiSTer2MEGA65 Porting Guide or the friendly MEGA65 community on Discord.