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An unknown video mode support on early CD-i models

>> Thursday, July 26, 2007

And another story by our CD-i developers team: Charles and cdifan! "While developing Frog Feast, I (well we, hello CD-I Fan!) stumbeld on a video mode only present on Mini MMC based boards. There is a 320x224 (or 256 in PAL ) mode supported on the systems such as the 205/910, 350 and, 605. This may be present in other models, but it didn't show up, in the Frog Feast tests. This is what caused the corrupt display experience by a few people. This mode matches the resolution of game systems such as the Sega Genesis/CD and TurboGrafx 16 and, Amiga/Atari ST computer systems. I'm not sure this is a fully supported mode even on the Mini MMC based boards, as there was some pixel garbage in the lower border area, that could not be cleared out."

"If the MCD212 chip was based on a previous chipset, it may've been left over functionality from the earlier chip. There's a document somewhere that details the chips used in each CD-i model. Since the MCD212 was used in other models, the RTOS must not allow the bits to be left unset in other models.

I started investigating why Frog Feast was not displaying correctly on my CD-I 605, and was able to determine the width and height, by drawing lines. Looking into the Balboa source I found both parts of the cause, but didn't put them together. CD-I Fan replied with an e-mail containing both pieces of information, which got me looking at the Green Book again. I noticed that I had overlooked the bit in the 'reload display parameter' instruction, I'd already noticed and corrected the bits in the 'image coding method' instruction.

Although Balboa isn't a good library for game development, it does provide source code that would help a programmer understand CD-I programming. It provides the correct way to interface with the CD RTOS. Unfortunately for me, I found it too late in the process."


cdifan: "The Green Book explicitly defines the above three bits as required to be set, but does not tell you what happens if you forget to set them. Well, Charles found out the hard way: on Mini-MMC hardware you get a different video resolution; on later hardware it has no effect. I suspect that on Maxi-MMC hardware (CD-i 18x series) the effect would have been similar.

Charles actually happened to confirm both my best hopes and worst fears about using CD-i Emulator for development. He found the various tracing and debugging aids (which are much more powerful then whatever was available at the time) invaluable, but also managed to get stuck on the differences between the emulator and "real hardware" in several cases (some of which were bugs in CD-i Emulator, but others where not).

The experience has been enlightening and got me thinking about ways to support developement with the emulator. Bitwise validation of the Display Control Program was easy to add and presto, out rolled the three bits! Of course, Charles had already noticed them by bitwise comparison of DCPs from various other CD-i titles including the early Balboa version of Frog Feast, which speaks volumes about the amount of effort he must have thrown at the problem. Hats off!

About the various hardware versions... Some of this is documented in the Technical Notes series which should appear on ICDIA sometime soon. Early CD-i models used a separate decoding chip per video plane, called VSC (Video System Controller?) on Maxi-MMC and VSR (Video System Revised?) on Mini-MMC, with another chip called VSD (Video System Decoder?) used to combine the outputs of the two video planes. This chipset generation supports the weird resolutions in hardware, but I have not been able to find any software support for it. It may have been a holdover from early development or an attempt to make the chipset reusable for other purposes as well.

The Motorola MCD212 reimplemented the functions of these chips on a single chip called VDSC (Video Decoder and System Controller), and I guess in the reimplementation the "undocumented" functionality got dropped. The VDSC is used in all CD-i players from Mono-I on.

ICDIA has a Comparison table of all Philips and Philips-build consumer CD-i players listing the board types of each CD-i player; the Player Support section of the CD-i Emulator website shows the board types of each CD-i player in the tooltips; the CD-i Types section lists the chipsets used in each board type."


If you want more info: Check the forum.

By: Charles Doty, cdifan

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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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