MiSTer and MEGA65 this autumn: workstation cores, a growing Amiga and an argument about AI

The two FPGA platforms most vintage-computer owners use had a busy autumn. The official MiSTer distribution added cores for workstations that have never had a hardware recreation of this kind, among them a NeXTcube, a Silicon Graphics Indy, three Sun machines and a Cray X-MP. The question of cores written with AI tools, which split the MiSTer community in July, has not gone away: two of the new cores say they were made that way. On the MEGA65, Dan Sanderson's October digest counted a "Summer of Cores", and one of them, an unofficial Amiga core, has published fifteen releases and a pre-release since 6 October. Release dates and file names here come from the projects' GitHub repositories as they stood on 26 October.

Workstations on a MiSTer

The new machines arrived through the MiSTer-devel organisation on GitHub, and every one named below has a core file in the _Computer folder of the MiSTer Distribution repository, the set of files that the MiSTer Downloader installs.

The NeXT core recreates a NeXTcube with a 68040, and its README says it boots NeXTSTEP 3.3; a second core, for the NeXTstation Turbo Color, boots to the colour desktop and is marked as work in progress. The SGI Indy core runs SGI's own boot PROM and IRIX 5.3 on a recreated MIPS R4600 at 50 MHz, and, its developers say, reaches the graphical login in about 90 seconds. There are separate cores for the Sun-2/160, the Sun-3/60, which its README calls "early, but it boots SunOS", and the SPARCstation 20, which needs the MiSTer SDRAM board. Apple machines include the Macintosh SE/30, which runs System 6 and 7 and the A/UX 3.1 Unix, the related IIcx, the Quadra 800, the Macintosh LC and the Apple III. Further afield there are Fujitsu's FM-7 and FM77AV and the Soyuz-Neon PK-11/16, a Soviet PDP-11-compatible computer of 1991 of which, the README says, about 200 were made. A PC/AT core built around a 286-compatible CPU has a repository in the organisation but was not yet in the Distribution.

Main_MiSTer, the repository for the platform's main program, has kept pace with support code for these machines. Its latest release build, MiSTer_20261010, is from 10 October, and commits since then have added 68EC030 and faster 68030 options for the Minimig Amiga core, CD32 discs with up to 99 tracks and WOZ conversion fixes for Apple II disk images. The newest, on 26 October, adds Main support for Bandai's Pippin.

The argument over AI-written cores

On 28 July Time Extension reported a "sharp rise in AI-assisted cores" for MiSTer, many of them apparently built from MAME's data rather than from studies of original arcade boards, and said they were being added to the update_all script without thorough review or clear labelling. The developer Jotego, whose cores are built from schematics of the original hardware, had written the day before that such work "turns the platform into a second class MAME, that tries to emulate what the emulator does". Others quoted by the site saw AI as a way to speed development up.

The new computer cores show the spread. Two of them say outright how they were made: the Apple III README opens with "Warning: This core is vibe coded", and the Cray X-MP README with "This was developed using AI". The NeXT core names the Previous software emulator as its hardware reference. The Mac SE/30 core says it was built from Apple's documentation and schematic and the chips' manuals, with MAME and WinUAE used as cross-checks. The other READMEs we read do not state how the code was written. The Distribution's README lists the tags its Downloader can use to include or exclude cores, and none of them marks AI-assisted work.

Arcade and media cores

RetroRGB's roundup of 29 August covered the arcade side. It listed a core for Sega's Outrunners with single- and dual-screen modes, a public beta of Konami's G.I. Joe from the Coin-Op Collection, Seibu's Denjin Makai and a Sega G80 vector core that plays Star Trek: Strategic Operations Simulator and Tac/Scan on a Z80 clocked at the original 3.867120 MHz. The System 32 core gained titles including Golden Axe: The Revenge of Death Adder and Jurassic Park, and rmonic79's Raiden core reached version 1.8 with a CPU boost option to reduce slowdown. Outside the arcade, the site counted two DVD playback cores in development, one in open beta that needs decrypted discs, and a Jellyfin media client called MiSTerFin.

MEGA65: an Amiga that keeps growing

Sanderson's digest of 17 October marked five years since the first MEGA65 pre-orders and the 500th file on the project's Filehost. Its list of cores led with Megamiga, a fork by johey of sy2002's Amiga 500 core that uses the SDRAM on R6 mainboards. The version Sanderson linked, 0.3.0, added A600 and A1200 profiles with the ECS and AGA chipsets. It has moved on since. Megamiga's GitHub page lists sixteen releases between 6 and 19 October: an RTG graphics card for Picasso96 in 0.4.0, a 100 Mbit network card on the MEGA65's Ethernet port in 0.5.0, a 68040 with MMU, FPU and caches at 42 MHz in 0.6.0, and in 0.6.4 an A4000 profile and Gayle IDE, with notes that Linux 6.18 boots to a shell. Its release packages are for R6 boards only, it needs a Kickstart ROM the owner supplies, and its notes say it is not an official release of AExp, the core it is forked from.

The other cores in the roundup are steadier. Stefan Eilers's C128 core is at a 1.0 beta with virtual drives, and Caps Lock stands in for the 40/80 key. The C64 core by MJoergen and sy2002 has a version 6 alpha with a second virtual drive and .d81 support, and sy2002's Amiga 500 core has a feature-complete version 2 beta. Sanderson also lists an Apple IIe core in a version 2 beta, a 1.0 alpha for the Atari 800, version 1.5 of the Sinclair QL core for R6 boards, an Amstrad CPC 6128 core that reads real CPC disks in the MEGA65's own floppy drive, an Atari ST core, a recreation of the BIT90 and an experimental IMSAI 8080.

More cores than slots

The MEGA65 stores eight cores in flash, and Paul Gardner-Stephen wrote on his MEGA65 development blog on 31 August that more cores are now coming out than fit. His answer is a loader built on a Raspberry Pi Pico with its own microSD card, which pushes a core into the FPGA through the mainboard's JTAG header on request from the MEGA65. He wrote that he was "vibe-coding" the Pico's firmware. Sanderson's digest mentions genAI experiments too, among them eleven titles released by one author in four weeks. The official MEGA65 core is unchanged: its latest release is 0.97.2, from 28 September 2025.