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Why is CD-i support in MESS Emulator limited?

>> Thursday, December 29, 2011

It seems we don't have to expect big updates on the MESS CD-i driver, because the author struggles to understand the system. It's a very complex system and if CD-i Fan wasn't around to help there would probably no CD-i MESS driver at all. A few paragraphs to display the current situation. Why is CD-i support in MESS Emulator limited?

"Because to work on the current CD-i driver any further [is very difficult]. I'll be happy to look into it if anyone ever procures dumps of the internal ROMs for the various peripheral MCUs that correspond to the specific CD-i board revision that MESS currently emulates, but beyond that I'd just be piling even more hacks on top of what is already a hack." ... "From what I can see the games for the system are designed in a fairly abstract manner, near enough an old style sandbox, designed to survive hardware changes because Philips designed it as the ultimate 'future-proof' multimedia system (however foolish that ended up being). There are probably a few key bugs in the implementation causing the vast majority of the problems. It's an impressive driver, don't get me wrong, but from my own study of it I don't feel it actually *needs* the internal ROMs to improve compatibility, afaik the standalone CDi emu does fine without them."

"To be quite honest, it is a very simple system, at least the Mono-II. The real problem comes from the abstraction that you mentioned above. By virtue of all of these different games going through the same core I/O functions that are supplied by the BIOS, there is an enormous lack of test cases. I have a bunch of CD-i games that all hit the hardware in more or less the same way."

CD-i Fan: "I have no more chip documentation then you do, in fact I originally had less since I worked on a different board (MiniMMC, it uses the (at the time) undocumented 2xVSC+VSD chips instead of the documented VDSC). My only "plus" is some years of headstart and a very good familiarity with the system as a developer. It does make me wonder where MESS CD-i would be without me; I think both emulators ended up better as a result of it. All of that aside, I sincerely believe that most current emulation bugs (in either emulator) would not be easily solved even with the contents of the internal ROMs; these bugs are probably only peripherally related to the contents of those ROMs."

"By contrast, I see the CD-i as a crap console that has only gone unemulated in an open manner for so long because people care so little about it. It's not a coincidence, in my opinion, that both more-popular and less-popular consoles and computers have been emulated in MESS. That both more-complex and less-complex systems have been emulated in both MESS and MAME. I was interested in emulating the CD-i because despite not knowing the ins and outs of all of the different CD-i platforms that you have emulated, I sincerely doubt that any of them are more complex than the Nintendo 64, so it seemed like a pretty simple target to hit until I found out that nobody ever bothered to leak any significant amount of register-level programming documentation."

CD-i Fan: "On the technical front, it's inherent in emulating CD-i. It's hard to get accurate low-level emulation with the amount of undocumented hardware in the system; reverse engineering and HLE is the only way that functional emulation can be achieved for a reasonable cost (time or money). I know that HLE is not the MESS way, but in this case it can't be helped. CD-i as a system is certainly way below the complexity of modern or even many older consoles, which makes it all the more challenging to get it properly emulated. That little register-level documentation was ever leaked is a consequence of the basic design of CD-i as a software API; to me as a software engineer it seems a better way then just fixing the hardware as so many contemporary consoles did. At the quality level, I think that the current CDIC emulation in MESS is essentially identical to that in CD-i Emu; there are still some problems in both emulators but I currently have no more ideas about fixing that then you do. I do not think that the CPU, VDSC and SLAVE emulations in either emulator have other then minor problems."

[Thanks, CD-i Fan, Just Desserts, Haze]

2 reacties:

CD-i Fan December 30, 2011 at 12:05 AM  

Thanks for a nice non-emotional abstract, Bas, the actual discussion on the forum was somewhat more heated :-)

Over a month ago I sent the MESS CD-i programmar full CD-i Emulator Mono-II sources (under NDA); he was happy with it and said it has helped him fix a few bugs but so far I haven't seen the results.

Austin January 7, 2012 at 5:50 AM  

Very interesting information, Bas! Thank you for posting this.

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Games 0-F

3rd Degree - PF Magic
7th Guest, The - Philips Freeland Studios
Accelerator - SPC/Vision
Adventure of the Space Ship Beagle, The - Denshi Media Services
Affaire Morlov, L' - Titus
Alfapet - Adatek
Alice in Wonderland - Spinnaker
Alien Gate - SPC Vision
Alien Odyssee - Argonaut
Aliens Interactive CD-i - Dark Vision Interactive
Ange et le Demon, L' - Smart Move
Apprentice, The - SPC Vision
Apprentice 2, The - Marvin's Revenge - SPC Vision
Arcade Classics - Philips ADS / Namco
Asterix - Caesar’s Challenge - Infogrames
Atlantis - The Last Resort - PRL Redhill (Philips ADS)
Axis and Allies - CapDisc
Backgammon - CapDisc
Battle Chess - Accent Media (for Interplay)
Battleship - CapDisc
Big Bang Show - Infogrames
BMP Puzzle - Circle (for ZYX)
Brain Dead 13 - Readysoft
Burn:Cycle - Trip Media
Caesar's World of Boxing - Philips POV
Caesar's World of Gambling - CD-I Systems
Cartoon Academy - Bits Corporation
CD-i mit der Maus - SPC Vision
CD Shoot - Eaglevision Interactive Productions
Change Angels Kick-off - HMO
Chaos Control - Infogrames
Christmas Country - Creative Media
Christmas Country - The Lost Levels - Creative Media
Christmas Crisis - DIMA
Clue - 3T Productions
Clue 2 - The mysteries continue - 3T Productions
Connect Four - CapDisc
Creature Shock - Argonaut (for Virgin)
Crime Patrol - CapDisc
Crow, The - Philips POV
Cyber Soldier Sharaku - Japan Interactive media
Dame was Loaded, The - Beam Software
Dark Castle - Philips POV
Dead End - Cryo
Defender of the Crown - Philips POV
Deja Vu - Icom Simulations
Deja Vu 2: Lost in Las Vegas - Icom Simulations
Demolition Man - Virgin Interactive Entertainment
Demon Driver - Haiku Studios
Discworld - Teeny Weeny Games
Dimo's Quest - SPC Vision
Domino - Wigant Interactive Media
Down in the Dumps - Haiku Studios
Dragon's Lair - Superclub / INTL CDI
Dragon's Lair 2- Time Warp - Superclub / INTL CDI
Drug wars - Crime Patrol II - CapDisc
Dungeons & Dragons - PF Magic
Earth Command - Visionary Media
Effacer - CapDisc
Escape from Cybercity - Fathom Pictures
Evidence - Microids
Falco & Donjon & The Sword of Inoxybur - BMi / Zephyr Studio
Family Games I - DIMA
Family Games II - Junk Food Jive - DIMA
Felix the Cat - Philips Sidewalk Studio
Flashback - Delphine/Tiertex (for US Gold)
Flinstones Wacky Inventions - Philips Funhouse
Fort Boyard: The Challenge - Microids
Frog Feast - Rastersoft

CD-i Games Index G-M

Go - CapDisc
Golden Oldies - SPC Vision
Golden Oldies II - SPC Vision
Golgo 13 - Japan Interactive Media
Great day at the races, A - CD-I Racing, Dove Films, Total Vision
Guignols de l'Info, Les - Canal+ Multimedia / INTL CDI
Heart of Darkness - Amazing Studio (for Virgin)
Hitchhiker's Guide to the Galaxy, The - Philips Kaleidoscope
Holland Casino CD-i - HMO
Hotel Mario - Philips Fantasy Factory
Inca - Coktel Vision
Inca 2 - Coktel Vision
International Tennis Open - Infogrames
Jack Sprite vs. The Crimson Ghost - PF Magic
Jeopardy - Accent Media
Jigsaw - Novalogic
Joe Guard - DIMA
John Dark: Psychic Eye - CapDisc
Joker's Wild!, The - Accent Media
Joker's Wild Jr., The - Accent Media
Kether - Infogrames
Kingdom - The far reaches - CapDisc
Kingdom 2 - Shadoan - CapDisc
Labyrinth of Crete - Philips Funhouse
Laser Lords - Spinnaker
Last Bounty Hunter, The - CapDisc
Legend of the Fort - Microids
Lemmings - DMA Design / Psygnosis
Lettergreep - Wigant Interactive Media
Lingo - SPC Vision
Link - The faces of evil - Animation Magic
Lion King, The - Virgin Interactive Entertainment
Litil Divil - Gremlin Graphics
Litil Divil 2: Limbo Years - Gremlin Graphics
Lords of the rising sun - Philips POV
Lost Eden - Cryo (for Virgin)
Lost Ride, The - Formula (Lost Boys)
Lucky Luke - The video game - SPC Vision
Mad Dog McCree - CapDisc
Mad Dog McCree II: The lost gold - CapDisc
Magic Eraser - Circle (for ZYX)
Mah-Jong - Japan Interactive Media
Making the Grade - 3T Productions
Man Before Man - Cryo
Marco Polo - Infogrames
Mario Takes America - CIGAM
Master Labyrinth - AVM AG/HQ
Mega Maze - CapDisc
Memory Works, The - Compact Disc Incorporated
Merlin's Apprentice - Philips Funhouse
Microcosm - Philips Freeland Studios
Micro Machines - Codemasters
Monty Python's Invasion from the Planet Skyron - Daedalus CD-i Productions
Mutant Rampage - Body Slam - Animation Magic
Myst - Sunsoft (for Cyan)
Mystic Midway - Rest in pieces - Philips POV
Mystic Midway 2 - Phantom Express - Philips POV

Compact Disc Interactive

Compact Disc Interactive

Games N-Z

Name that tune - Philips Fantasy Factory
New Day - Bits Corporation
NFL Hall of Fame Football - Philips POV
Othello - HMO
Pac Panic - Philips ADS / Namco
Palm Springs Open - ABC Sports / Fathom Pictures
Pool - SPC Vision
Pinball - CapDisc
Plunderball - ISG Productions
Power Hitter - ABC Sports / Fathom Pictures
Power Match - Two's Company
Pursue - BEPL
Pyramid Adventures - Compact Disc Incorporated
RAMRaid - PRL Redhill
Return To Cybercity - Fathom Pictures
Riddle of the Maze, The - Fathom Pictures
Riqa - Bits Corporation
Rise of the Robots - Mirage Technologies
Sargon Chess - Spinnaker
Scotland Yard Interactive - AVM AG/HQ
Secret Mission - Microids
Secret Name of Ra, The
Shaolin's Road - Infogrames
Skate Dude - Viridis
Smurfen, De - De Telesmurf - Infogrames
Solar Crusade - Infogrames
Solitaire - BEPL
Space Ace - Superclub / INTL CDI
Space Ranger - Studio Interactive
Special Operations Squadron - SPC Vision
Sport Freaks - SPC Vision
Star Trek - Philips POV
Star Wars: Rebel Assault - LucasArts
Steel Machine - SPC Vision
Striker Pro - Rage
Strip Poker Live - Greenpig Production
Strip Poker Pro - Interactive Pictures
Super Fighter - The Super Fighter Team / C&E
Super Mario's Wacky Worlds - NovaLogic
Surf City - Philips Sidewalk Studios
Tangram - Eaglevision Interactive Productions
Taco's Toyroom Troopers - Creative Media
Tankdoodle - Creative Media
Tetris - Philips POV
Tetsuo Gaiden - Creative Media
Text Tiles
Thieves' World - Electronic Arts
Tic-tac-toe - BEPL
Tox Runner - ISG Productions
Treasures of Oz - Philips Kaleidoscope
Ultra CD-i Soccer - Krisalis
Uncover featuring Tatjana - SPC Vision
Uninvited - Icom Simulations
Video Speedway - ISG Productions
Vinnie the Pinguin - Pandemonium Labs
Voyeur - Philips POV
Voyeur 2 - Philips POV
Whack-a-Bubble - Creative Media
What's it worth - Marshall Cavendish Multimedia / Spice
Who shot Johnny Rock? - CapDisc
Wordplay - BEPL
World Cup Golf - US Gold
Zaak Sam, De - Toneelschool NL
Zelda - The wand of Gamelon - Animation Magic
Zelda's Adventure - Viridis
Zenith - Radarsoft
Zombie Dinos From The Planet Zeltoid - Philips POV

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