| Name | Description | Year | Manufacturer | Rom | Clone | Sample |
| wyvernf0a | Wyvern F-0 | 1985 | Taito Corporation | wyvernf0 | wyvernf0 | |
| wyvernwg | Wyvern Wings (set 1) | 2001 | SemiCom (Game Vision license) | wivernwg | wivernwg | |
| wyvernwga | Wyvern Wings (set 2) | 2001 | SemiCom (Game Vision license) | wivernwg | wivernwg | |
| wzwaysll | Wizard Ways - Lady Luck (20139121, NSW/ACT) | 2003 | Aristocrat | aristmk6 | | |
| x07 | X-07 | 1983 | Canon | | | |
| x1 | X1 (CZ-800C) | 1982 | Sharp | | | |
| x1_001 | Seta X1-001 Sprites | | | | | |
| x1_010 | Seta X1-010 | | | | | |
| x1_012 | Seta X1-012 Tile Layer | | | | | |
| x1_keyboard | Sharp X1 Keyboard | | | | | |
| x168 | Xerox 16/8 | 1983 | Xerox | x820ii | x820ii | |
| x180 | unknown Yuvo Joy Stand game (set 1) | 1997 | Yuvo | | | |
| x180ii | unknown Yuvo Joy Stand game (set 2) | 1997 | Yuvo | | | |
| x1turbo | X1 Turbo (CZ-850C) | 1984 | Sharp | x1 | x1 | |
| x1turbo40 | X1 Turbo (CZ-862C) | 1985 | Sharp | x1 | x1 | |
| x1twin | X1 Twin (CZ-830C) | 1986 | Sharp | x1 | x1 | |
| x2201 | Xicor X2201 1024x1 NOVRAM | | | | | |
| x2210 | Xicor X2210 64x4 NOVRAM | | | | | |
| x2212 | Xicor X2212 256x4 NOVRAM | | | | | |
| x2222 | X2222 (final debug?) | 2000 | Oriental Soft / Promat | | | |
| x2222o | X2222 (5-level prototype) | 2000 | Oriental Soft / Promat | x2222 | x2222 | |
| x2404p | X2404P I2C Memory | | | | | |
| x24c01 | X24C01 I2C Memory | | | | | |
| x24c44_16 | Serial EEPROM X24C44 (16x16) | | | | | |
| x37 | X37 (prototype) | 1985 | Luxor | | | |
| x5jokers | X Five Jokers (Version 1.12) | 200? | Electronic Projects | | | |
| x68000 | X68000 | 1987 | Sharp | | | |
| x68030 | X68030 | 1993 | Sharp | x68000 | x68000 | |
| x68k_cz6bs1 | Sharp CZ-6BS1 SCSI-1 | | | | | |
| x68k_expansion_slot | Sharp X680x0 expansion slot | | | | | |
| x68k_hdc_image | SASI Hard Disk | | | | | |
| x68k_keyboard | Sharp X68000 Keyboard | | | | | |
| x68k_midi | X68000 MIDI Interface | | | | | |
| x68k_mouse | Sharp X68000 Mouse | | | | | |
| x68k_neptunex | Neptune-X | | | | | |
| x68ksupr | X68000 Super | 1990 | Sharp | x68000 | x68000 | |
| x68kxvi | X68000 XVI | 1991 | Sharp | x68000 | x68000 | |
| x76f041 | X76F041 Secure SerialFlash | | | | | |
| x76f100 | X76F100 Secure SerialFlash | | | | | |
| x80wc | X80 - War Command (ManilaMatic bootleg of Missile Command) | 1981 | bootleg (ManilaMatic) | missile | missile | |
| x820 | Xerox 820 | 1981 | Xerox | bigboard | bigboard | |
| x820ii | Xerox 820-II | 1983 | Xerox | | | |
| x820kb | Xerox 820 Keyboard | | | | | |
| xa | Philips 80c51 XA | | | | | |
| xavaero | XaviX Aerostep (XaviXPORT, Japan) | 2005 | SSD Company LTD | xavjmat | xavjmat | |
| xavbaseb | XaviX Baseball (XaviXPORT) | 2004 | SSD Company LTD | | | |
| xavbassf | XaviX Bass Fishing (XaviXPORT) | 2004 | SSD Company LTD | | | |
| xavbowl | XaviX Bowling (XaviXPORT) | 2004 | SSD Company LTD | | | |
| xavbowlj | XaviX Bowling (XaviXPORT, PT2-BWL-11, Japan) | 2005 | SSD Company LTD | xavbowl | xavbowl | |
| xavbox | XaviX Boxing (XaviXPORT) | 2004 | SSD Company LTD | | | |
| xavcheck | XaviX Aero Check & Balance (XaviXPORT, Japan) | 2006 | SSD Company LTD | | | |
| xavix | XaviX (SSD 97 / SSD 98) | | | | | |
| xavix_adc | XaviX ADC | | | | | |
| xavix_anport | XaviX Analog ports | | | | | |
| xavix_madfb_ball | XaviX / Radica Football Ball | | | | | |
| xavix_math | XaviX Math Unit | | | | | |
| xavix_mtrk_wheel | XaviX / Radica Monster Truck Steering Wheel | | | | | |
| xavix_sound | XaviX Sound | | | | | |
| xavix2 | Xavix 2 CPU | | | | | |
| xavix2000 | XaviX (SSD 2000) | | | | | |
| xavix2002 | XaviX (SSD 2002) (SuperXaviX) | | | | | |
| xavix2002io | XaviX 2002 IO | | | | | |
| xavjmat | Jackie Chan J-Mat Fitness (XaviXPORT) | 2005 | SSD Company LTD | | | |
| xavmusic | XaviX Music & Circuit (XaviXPORT) | 2007 | SSD Company LTD | | | |
| xavpkjr | PowerKIDS Jr. (XaviXPORT, Japan) | 2007 | SSD Company LTD | | | |
| xavtenni | XaviX Tennis (XaviXPORT) | 2004 | SSD Company LTD | | | |
| xb42639 | Apricot XEN-S (Venus I Motherboard 286) | 1989 | Apricot | ibm5170 | ibm5170 | |
| xb42639a | Apricot XEN-S (Venus II Motherboard 286) | 1990 | Apricot | ibm5170 | ibm5170 | |
| xb42663 | Apricot Qi 300 (Rev D,E & F Motherboard) | 1988 | Apricot | ibm5170 | ibm5170 | |
| xb42664 | Apricot XEN-S (Venus I Motherboard 386) | 1989 | Apricot | ibm5170 | ibm5170 | |
| xb42664a | Apricot XEN-S (Venus II Motherboard 386) | 1990 | Apricot | ibm5170 | ibm5170 | |
| xbase09 | XBase 09 Midi Controlled Analogue Drum Module | 1997 | JoMoX | | | |
| xbox | XBOX | 2001 | Microsoft | | | |
| xc1701 | Xilinx 1,048,576 bit Serial PROM | | | | | |
| xc1702l | Xilinx 2,097,152 bit Serial PROM | | | | | |
| xc1704l | Xilinx 4,194,304 bit Serial PROM | | | | | |
| xc17128e | Xilinx 131,072 bit Serial PROM | | | | | |
| xc17256e | Xilinx 262,144 bit Serial PROM | | | | | |
| xc1736e | Xilinx 36,288 bit Serial PROM | | | | | |
| xc17512l | Xilinx 524,288 bit Serial PROM | | | | | |
| xc1765e | Xilinx 65,536 bit Serial PROM | | | | | |
| xd88_01 | XD88/01 | 1990 | Tektronix | | | |
| xday2 | X-Day 2 (Japan) | 1995 | Namco | | | |
| xds_kbd_hle | XDS Keyboard (HLE) | | | | | |
| xds19p | XDS-19P | 1990 | Visual Technology | | | |
| xegs | Atari XE Game System | 1987 | Atari | | | |
| xen_daisy | Apricot XEN daisy chain abstraction | | | | | |
| xenon | Xenon | 1980 | Bally | | | genpin |
| xenonf | Xenon (French) | 1980 | Bally | xenon | xenon | genpin |
| xenophob | Xenophobe | 1987 | Bally Midway | | | |
| xevi3dg | Xevious 3D/G (World, XV32/VER.B) | 1995 | Namco | | | |
| xevi3dga | Xevious 3D/G (World, XV32/VER.A) | 1995 | Namco | xevi3dg | xevi3dg | |
| xevi3dgj | Xevious 3D/G (Japan, XV31/VER.A) | 1995 | Namco | xevi3dg | xevi3dg | |
| xevios | Xevios | 1982 | bootleg | xevious | xevious | |
| xevious | Xevious (Namco) | 1982 | Namco | | | |
| xeviousa | Xevious (Atari, harder) | 1982 | Namco (Atari license) | xevious | xevious | |
| xeviousb | Xevious (Atari) | 1982 | Namco (Atari license) | xevious | xevious | |
| xeviousc | Xevious (Atari, Namco PCB) | 1982 | Namco (Atari license) | xevious | xevious | |
| xexex | Xexex (ver EAA) | 1991 | Konami | | | |
| xexexa | Xexex (ver AAA) | 1991 | Konami | xexex | xexex | |
| xexexj | Xexex (ver JAA) | 1991 | Konami | xexex | xexex | |
| xeye | X'eye (USA, NTSC) | 1993 | JVC | | | |
| xfiles | The X-Files | 1999 | dgPIX Entertainment Inc. | | | |
| xfiles2 | X-Files (CPU 2.04, display A2.01) | 1997 | Sega | xfilesp | xfilesp | genpin |
| xfiles20 | X-Files (CPU 2.00, display A2.00) | 1997 | Sega | xfilesp | xfilesp | genpin |
| xfilesk | The X-Files (censored, Korea) | 1999 | dgPIX Entertainment Inc. | xfiles | xfiles | |
| xfilesp | X-Files (CPU 3.03, display A3.00) | 1997 | Sega | | | genpin |
| xfilespf | X-Files (CPU 3.03, display F3.00, France) | 1997 | Sega | xfilesp | xfilesp | genpin |
| xforce | X Force | 1987 | Tecnoplay | | | genpin |
| xga_copro | IBM XGA Coprocessor | | | | | |
| xiaoao | Xiao Ao Jiang Hu (China, Ver. 1.00) | 1999 | Subsino | bishjan | bishjan | |
| xiistag | XII Stag (V2.01J 2002/6/26 22:27) | 2002 | Triangle Service | coh3002t | | |
| xing48 | Xing Wireless Interactive TV Game 'Wi TV Zone' 48-in-1 (Europe, PAL) | 200? | Xing | | | |
| xiprocessor | Xi processor board | 2012 | Sergey Kiselev | ibm5150 | ibm5150 | |
| xjinhuang | Xin Jin Huangguan (V400CN) | 1997 | IGS | | | |
| xl25 | XL 25 | 1983 | Vulcan Electronics | | | |
| xm200 | XM200 Orchestra Module | 1990 | Orla | | | |
| xm3301 | Toshiba XM-3301 CD-ROM Drive | | | | | |
| xmap9 | SGI XMAP9 | | | | | |
| xmcota | X-Men: Children of the Atom (Europe 950331) | 1994 | Capcom | | | |
| xmcotaa | X-Men: Children of the Atom (Asia 950105) | 1994 | Capcom | xmcota | xmcota | |
| xmcotaar1 | X-Men: Children of the Atom (Asia 941219) | 1994 | Capcom | xmcota | xmcota | |
| xmcotaar2 | X-Men: Children of the Atom (Asia 941217) | 1994 | Capcom | xmcota | xmcota | |
| xmcotab | X-Men: Children of the Atom (Brazil 950331) | 1994 | Capcom | xmcota | xmcota | |
| xmcotah | X-Men: Children of the Atom (Hispanic 950331) | 1994 | Capcom | xmcota | xmcota | |
| xmcotahr1 | X-Men: Children of the Atom (Hispanic 950105) | 1994 | Capcom | xmcota | xmcota | |
| xmcotaj | X-Men: Children of the Atom (Japan 950105) | 1994 | Capcom | xmcota | xmcota | |
| xmcotaj1 | X-Men: Children of the Atom (Japan 941222) | 1994 | Capcom | xmcota | xmcota | |
| xmcotaj2 | X-Men: Children of the Atom (Japan 941219) | 1994 | Capcom | xmcota | xmcota | |
| xmcotaj3 | X-Men: Children of the Atom (Japan 941217) | 1994 | Capcom | xmcota | xmcota | |
| xmcotajr | X-Men: Children of the Atom (Japan 941208 rent version) | 1994 | Capcom | xmcota | xmcota | |
| xmcotar1 | X-Men: Children of the Atom (Europe 950105) | 1994 | Capcom | xmcota | xmcota | |
| xmcotar1d | X-Men: Children of the Atom (Europe 950105 Phoenix Edition) (bootleg) | 1994 | bootleg | xmcota | xmcota | |
| xmcotau | X-Men: Children of the Atom (USA 950105) | 1994 | Capcom | xmcota | xmcota | |
| xmen | X-Men (4 Players ver EBA) | 1992 | Konami | | | |
| xmen2pa | X-Men (2 Players ver AAA) | 1992 | Konami | xmen | xmen | |
| xmen2pe | X-Men (2 Players ver EAA) | 1992 | Konami | xmen | xmen | |
| xmen2pj | X-Men (2 Players ver JAA) | 1992 | Konami | xmen | xmen | |
| xmen2pu | X-Men (2 Players ver UAB) | 1992 | Konami | xmen | xmen | |
| xmen6p | X-Men (6 Players ver ECB) | 1992 | Konami | xmen | xmen | |
| xmen6pu | X-Men (6 Players ver UCB) | 1992 | Konami | xmen | xmen | |
| xmena | X-Men (4 Players ver AEA) | 1992 | Konami | xmen | xmen | |
| xmenaa | X-Men (4 Players ver ADA) | 1992 | Konami | xmen | xmen | |
| xmenabl | X-Men (4 Players ver AEA, bootleg) | 1992 | bootleg | xmen | xmen | |
| xmenj | X-Men (4 Players ver JBA) | 1992 | Konami | xmen | xmen | |
| xmenja | X-Men (4 Players ver JEA) | 1992 | Konami | xmen | xmen | |
| xmenu | X-Men (4 Players ver UBB) | 1992 | Konami | xmen | xmen | |
| xmenua | X-Men (4 Players ver UEB) | 1992 | Konami | xmen | xmen | |
| xmpu4chrpalboot19 | MPU4 bootleg Characteriser (fixed returns) | | | | | |
| xmultipl | X Multiply (World, M81 hardware) | 1989 | Irem | | | |
| xmultiplm72 | X Multiply (Japan, M72 hardware) | 1989 | Irem | xmultipl | xmultipl | |
| xmvsf | X-Men Vs. Street Fighter (Europe 961004) | 1996 | Capcom | | | |
| xmvsfa | X-Men Vs. Street Fighter (Asia 961023) | 1996 | Capcom | xmvsf | xmvsf | |
| xmvsfar1 | X-Men Vs. Street Fighter (Asia 961004) | 1996 | Capcom | xmvsf | xmvsf | |
| xmvsfar2 | X-Men Vs. Street Fighter (Asia 960919) | 1996 | Capcom | xmvsf | xmvsf | |
| xmvsfar3 | X-Men Vs. Street Fighter (Asia 960910) | 1996 | Capcom | xmvsf | xmvsf | |
| xmvsfb | X-Men Vs. Street Fighter (Brazil 961023) | 1996 | Capcom | xmvsf | xmvsf | |
| xmvsfh | X-Men Vs. Street Fighter (Hispanic 961004) | 1996 | Capcom | xmvsf | xmvsf | |
| xmvsfj | X-Men Vs. Street Fighter (Japan 970113) | 1996 | Capcom | xmvsf | xmvsf | |
| xmvsfjr1 | X-Men Vs. Street Fighter (Japan 961023) | 1996 | Capcom | xmvsf | xmvsf | |
| xmvsfjr2 | X-Men Vs. Street Fighter (Japan 961004) | 1996 | Capcom | xmvsf | xmvsf | |
| xmvsfjr3 | X-Men Vs. Street Fighter (Japan 960910) | 1996 | Capcom | xmvsf | xmvsf | |
| xmvsfjr4 | X-Men Vs. Street Fighter (Japan 960909) | 1996 | Capcom | xmvsf | xmvsf | |
| xmvsfr1 | X-Men Vs. Street Fighter (Europe 960910) | 1996 | Capcom | xmvsf | xmvsf | |
| xmvsfu | X-Men Vs. Street Fighter (USA 961023) | 1996 | Capcom | xmvsf | xmvsf | |
| xmvsfu1d | X-Men Vs. Street Fighter (USA 961004 Phoenix Edition) (bootleg) | 1996 | bootleg | xmvsf | xmvsf | |
| xmvsfur1 | X-Men Vs. Street Fighter (USA 961004) | 1996 | Capcom | xmvsf | xmvsf | |
| xmvsfur2 | X-Men Vs. Street Fighter (USA 960910) | 1996 | Capcom | xmvsf | xmvsf | |
| xor100 | XOR S-100-12 | 1980 | XOR Data Science | | | |
| xorwflat | Xor World (different hardware, ver 1.1, checksum 3333BA, prototype) | 1990 | Gaelco | | | |
| xorwflata | Xor World (different hardware, ver 1.1, checksum 333462, prototype) | 1990 | Gaelco | xorwflat | xorwflat | |
| xorwldms | Xor World (Modular System, prototype, set 1) | 1990 | Gaelco | | | |
| xorwldmsa | Xor World (Modular System, prototype, set 2) | 1990 | Gaelco | xorwldms | xorwldms | |
| xorworld | Xor World (ver 1.2, checksum DB5D0F, prototype) | 1990 | Gaelco | | | |
| xorworlda | Xor World (ver 1.2, checksum DB5D10, prototype) | 1990 | Gaelco | xorworld | xorworld | |
| xpander | Xpander | 1984 | Oberheim | | | |
| xplan | X-Plan (Ver. 101) | 2006 | Subsino | | | |
| xr68c681 | XR68C681 DUART | | | | | |
| xrally | Xtreme Rally / Off Beat Racer! | 1998 | SNK | hng64 | | |
| xreel | X-Reel | 2002 | Subsino (ECM license) | queenbee | queenbee | |
| xsandos | X's & O's | 1983 | Bally | | | genpin |
| xsedae | X Se Dae Quiz (Korea) | 1995 | Dream Island | | | |
| xsleena | Xain'd Sleena (World) | 1986 | Technos Japan (Taito license) | | | |
| xsleenab | Xain'd Sleena (bootleg, set 1) | 1986 | bootleg | xsleena | xsleena | |
| xsleenaba | Xain'd Sleena (bootleg, bugfixed) | 1987 | bootleg | xsleena | xsleena | |
| xsleenabb | Xain'd Sleena (bootleg, set 2) | 1987 | bootleg | xsleena | xsleena | |
| xsleenaj | Xain'd Sleena (Japan) | 1986 | Technos Japan | xsleena | xsleena | |
| xt_hdc | Generic PC-XT Fixed Disk Controller | | | | | |
| xt446 | Yamaha XT446 synth (embedded MU100B) | | | | | |
| xtensa | Tensilica Xtensa core | | | | | |
| xtheball | X the Ball | 1991 | Rare | | | |
| xtide | XT-IDE Fixed Drive Adapter | | | | | |
| xtom3d | X Tom 3D | 1999 | Andamiro / Jamie System Development | | | |
| xtrain | X-Train (Ver. 1.3) | 1999 | Subsino | | | |
| xtrial | Xtrial Racing (ver JAB) | 2002 | Konami | kviper | | |
| xtrmhnt2 | Extreme Hunting 2 | 2006 | Sega | awbios | | |
| xtrmhunt | Extreme Hunting | 2004 | Sammy | awbios | | |
| xunitvid | Midway X-Unit Video | | | | | |
| xvd701 | JVC XV-D701 | | | | | |
| xxmissio | XX Mission | 1986 | UPL | | | |
| xybots | Xybots (rev 2) | 1987 | Atari Games | | | |
| xybots0 | Xybots (rev 0) | 1987 | Atari Games | xybots | xybots | |
| xybots1 | Xybots (rev 1) | 1987 | Atari Games | xybots | xybots | |
| xybotsf | Xybots (French, rev 3) | 1987 | Atari Games | xybots | xybots | |
| xybotsg | Xybots (German, rev 3) | 1987 | Atari Games | xybots | xybots | |
| xyddz | Xiaoyao Dou Dizhu (V216CN) | 200? | IGS | | | |
| xyddzhh | Xingyun Dou Dizhu | 2006 | Herb Home | | | |
| xydn | Xiyou Douniu (S110CN) | 200? | IGS | | | |
| xymg | Xingyun Manguan (China, V651C, set 1) | 1996 | IGS | | | |
| xymga | Xingyun Manguan (China, V651C, set 2) | 1996 | IGS | xymg | xymg | |
| xyonix | Xyonix | 1989 | Philko | | | |
| xypdk | Xingyun Pao De Kuai (V106CN) | 2005 | IGS | | | |
| xypmd | Xingyun Paomadi Super (V401CN) | 2003 | IGS | | | |
| xypmda | Xingyun Paomadi (unknown ver) | 1999 | IGS | xypmd | xypmd | |
| y2404 | Y2404 | | | | | |
| y301xl | 301 XL (Yeno) | 1988 | Yeno / Bray Research | | | |
| y416xl | 416 XL (Yeno) | 1989 | Yeno | | | |
| y503iiir | YIS-503 III R (MSX2, USSR) | 1985 | Yamaha | | | |
| y503iiire | YIS-503 III R (MSX2, Estonian) | 198? | Yamaha | y503iiir | y503iiir | |
| y503iir | YIS503IIR (MSX1, USSR) | 1985 | Yamaha | yis503 | yis503 | |
| y503iir2 | YIS503IIR (MSX1, Estonian) | 1986 | Yamaha | yis503 | yis503 | |
| y532xl | 532 XL (Yeno) | 1989 | Yeno | | | |
| y805128 | YIS805/128 (MSX2, Japan) | 1986 | Yamaha | y805256 | y805256 | |
| y805128r2 | YIS805/128R2 (MSX2, USSR) | 1986 | Yamaha | y805256 | y805256 | |
| y805128r2e | YIS805/128R2 (MSX2, Estonian) | 198? | Yamaha | y805256 | y805256 | |
| y805256 | YIS805/256 (MSX2, Japan) | 198? | Yamaha | | | |
| y8950 | Y8950 OPL MSX-Audio | | | | | |
| yachtmn | Yachtsman | 1982 | Sanritsu / Esco | mermaid | mermaid | |
| yakyuken | The Yakyuken (bootleg) | 1982 | bootleg | | | |
| yamagchi | Go Go Mr. Yamaguchi / Yuke Yuke Yamaguchi-kun | 1985 | Kaneko / Taito | | | |
| yamato | Yamato (set 1) | 1983 | Sega | | | |
| yamatoa | Yamato (set 2) | 1983 | Sega | yamato | yamato | |
| yamatou | Yamato (US) | 1983 | Sega | yamato | yamato | |
| yamyam | Yam! Yam!? | 1990 | Dooyong | | | |
| yamyamk | Yam! Yam! (Korea) | 1990 | Dooyong | yamyam | yamyam | |
| yanchamr | Kaiketsu Yanchamaru (Japan) | 1986 | Irem | kidniki | kidniki | |
| yankeedo | Yankee DO! | 1982 | hack | mrdo | mrdo | |
| yarunara | Mahjong Yarunara (Japan) | 1991 | Dynax | | | |
| yattrmnp | Yatterman Plus (J 981006 V1.000) | 1998 | Sega | stvbios | | |
| yc64 | YC-64 (MSX1, Europe) | 1984 | Yashica | | | |
| yellowcbb | Yellow Cab (bootleg) | 1984 | bootleg | kamikcab | kamikcab | |
| yellowcbj | Yellow Cab (Japan) | 1984 | Data East Corporation | kamikcab | kamikcab | |
| yes | :YES | 1985 | Philips | | | |
| yesnoj | Yes/No Sinri Tokimeki Chart | 1992 | Taito Corporation | | | |
| ygv608 | YGV608 VDP | | | | | |
| yiear | Yie Ar Kung-Fu (version I) | 1985 | Konami | | | |
| yiear2 | Yie Ar Kung-Fu (version G) | 1985 | Konami | yiear | yiear | |
| yieartf | Yie Ar Kung-Fu (bootleg GX361 conversion) | 1985 | bootleg | yiear | yiear | |
| yis303 | YIS303 (MSX1, Japan) | 1984 | Yamaha | | | |
| yis503 | YIS503 (MSX1, Japan) | 1984 | Yamaha | | | |