This repository contains all the files that you'll want in your MiSTer.
You may download all of them at once as a zip through the following link. Once you have them, place them as-is in your SD card, and everything should work out of the box.
If you want to check more about the MiSTer project, please check this wiki.
For downloading all of these files in an automatic fashion, use this tool.
.config, acornatom, acornelectron, adam, adctest, adventurevision, alicemc10, all_filters, altair8800, alternatives, amiga, amstrad, amstrad-pcw, amstradpcw, ao486, apogee, apple-i, apple-ii, aquarius, arcade, arcade-arkanoid, arcade-asteroids, arcade-asteroidsdeluxe, arcade-astrocade, arcade-atarisys1, arcade-ataritetris, arcade-athena, arcade-bagman, arcade-bankpanic, arcade-battlezone, arcade-berzerk, arcade-blackwidow, arcade-blockade, arcade-bombjack, arcade-bosconian, arcade-breakout, arcade-burgertime, arcade-burningrubber, arcade-canyonbomber, arcade-cave, arcade-centipede, arcade-chameleon, arcade-computerspace, arcade-congobongo, arcade-cores, arcade-cosmic, arcade-cosmicguerilla, arcade-crazyballoon, arcade-crazyclimber, arcade-crazykong, arcade-crystalcastles, arcade-defender, arcade-digdug, arcade-dominos, arcade-donkeykong, arcade-donkeykong3, arcade-donkeykongjunior, arcade-dorodon, arcade-dottorikun, arcade-druaga, arcade-exerion, arcade-exidy2, arcade-expressraider, arcade-finalizer, arcade-foodfight, arcade-freeze, arcade-frenzy, arcade-galaga, arcade-galaxian, arcade-galivan, arcade-gaplus, arcade-gauntlet, arcade-gyruss, arcade-ikariwarriors, arcade-inferno, arcade-iremm107, arcade-iremm62, arcade-iremm72, arcade-iremm92, arcade-ironhorse, arcade-jackal, arcade-jailbreak, arcade-joust2, arcade-kickandrun, arcade-ladybug, arcade-lunarlander, arcade-mariobros, arcade-mcr1, arcade-mcr2, arcade-mcr3, arcade-mcr3mono, arcade-mcr3scroll, arcade-missilecommand, arcade-moonpatrol, arcade-mrdo, arcade-mrjong, arcade-mysticmarathon, arcade-ninjakun, arcade-pacman, arcade-pengo, arcade-penguinkunwars, arcade-performan, arcade-phoenix, arcade-pleiads, arcade-polyplay, arcade-pong, arcade-pooyan, arcade-popeye, arcade-psychic5, arcade-qbert, arcade-rallyx, arcade-riverpatrol, arcade-robotron, arcade-rshnatk, arcade-scootershooter, arcade-scramble, arcade-segasys1, arcade-segavicz80, arcade-silverland, arcade-slapfight, arcade-sms, arcade-snk_triplez80, arcade-solomonskey, arcade-sonson, arcade-spaceinvaders, arcade-spacerace, arcade-sprint1, arcade-sprint2, arcade-subs, arcade-superbreakout, arcade-suprloco, arcade-taitosj, arcade-tankbattalion, arcade-tecmo, arcade-tiamc1, arcade-timepilot, arcade-timepilot84, arcade-tnkiii, arcade-traverseusa, arcade-tropicalangel, arcade-turkeyshoot, arcade-ultratank, arcade-vball, arcade-xevious, arcade-xsleena, arcade-zaxxon, arcade-zigzag, arcadelpf, arcadia, archie, arduboy, astrocade, atari2600, atari5200, atari7800, atari800, atarilynx, atarist, avision, ay-3-8500, bbcbridgecompanion, bbcmicro, bios, bk0011m, c128, c16, c64, casio_pv-1000, casio_pv-2000, channelf, cheats, chess, chip8, coco2, coco3, coleco, colecoadam, colecovision, complexmultichromatic, computer, computer-cores, console, console-cores, contrast_boost, cores, corespecific, creativision, crt-simulation, displayspecific, docs, downloader, downloaderlatest, drv, edsac, eg2000, epochgalaxyii, essential, extra-utilities, famicom, filters, filters_audio, filters_video, flappy, flappybird, font, galaksija, gamate, gameboy, gameboy2p, gameboyadvance, gameboycolor, gamecontrollerdb, gamegear, gamenwatch, gameoflife, games, gamma, gb, gba, gba2p, gbc, gbmidi, generalhardware, generallpf, genesis, genesis-core, genmidi, gnw, handheld2p, hbmame, homelab, inputtest, intellivision, interact, jupiter, laser, laser310, lcd-general, lcd-integeronly, linux, lynx48, macplus, mame, mastersystem, megacd, megadrive, megadrive-core, megaduck, memte, memtest, menu, mgl, minimig, minimigdb9, minimigrgb8, misterfirmware, misterlaggy, mra, msx, msx1, multicomp, myvision, n64, neogeo, nes, nintendo, odyssey2, old, ondra_spo186, orao, oric, other, other-cores, overlays, palettes, pc88, pc8801, pcengine, pcenginecd, pcxt, pdp1, pet2001, pmd85, pocketchallengev2, pokemonmini, poly_gamma, presets, psx, pure_gamma, ql, readme, rx78, s32x, samcoupe, saturn, scanlines-adaptive, scanlines-brighter, scanlines-standard, scripts, segacd, segamark3, service-cores, sgb, shadow_masks, sharpmz, simplemonochrome, slugcross, sms, snes, sordm5, specialist, spectrum, spmx, sufami, super_vision_8000, superfamicom, supergameboy, supernes, supernintendo, supervision, supervision8000, svi328, tatungeinstein, tgfx16, tgfx16-cd, tgfx16cd, ti-99_4a, ti994a, tomyscramble, tomytutor, trs-80, tsconf, turbografx, turbografx16, turbografx16cd, turbografxcd, uk101, upscaling-lanczosbicubicetc, upscaling-recommended, upscaling-sharpbilinear, utility, vc4000, vector-06c, vector06, vector06c, vectrex, vic20, wonderswan, wonderswancolor, x68000, yctxt, zx-spectrum, zx81, zxnext, zxspectrum