Nintendo released the Family Computer (Famicom) on July 15, 1983 in Japan for a cost of 14,800 Yen. Cartridges for the system typically cost 4,500-5,500 Yen. On February 21, 1986, Nintendo released the Family Computer Disk System accessory at a cost of 15,000 Yen. Disks with new games typically cost 2,600-3,400 Yen, but the cost to rewrite a game was only 500-600 Yen. At the time, Nintendo heavily promoted this peripheral as the future of gaming as it saw it.
Nintendo focused its efforts on the disk system for quite a long time. The last cartridge game it released for the Famicom before the disk system's release , Mach Rider, was released on November 21, 1985. It did not release another cartridge for two years (Punch-Out!!, November 21, 1987) and only had released ten cartridge games by the end of 1991. By contrast, excluding ports and revisions of cartridge games, Nintendo released twenty-six FDS games during the same time period.
The actual situation with cartridges became more complex than Nintendo wanted. While Nintendo was off in magnetic-media land, its third parties carried the disk-less console and developed new cartridge hardware to increase drastically the amount of ROM space available to the games. While the Disk System was not Nintendo's greatest success, it was hardly a failure. 19.35 million Famicoms were sold compared to 4.5 million disk systems. As it found its way into at least 20% of Japanese Famicoms, as an add-on it would appear to be successful. This is despite buyers having already paid 14,800 Yen for a Famicom. Nintendo made money off each console sold. Also, after the release of Famicom Grand Prix II: 3D Hot Rally on April 14, 1988, Nintendo no longer devoted exclusive games to the system, with the exception of PC-style adventure games.
Third parties interest in the system and the number of games released for it dried up by the end of 1988. Some major developers like Capcom and Namco did not devote much attention to the disk system. The main advantages of the disk system, namely space and saving, had quickly become affordable in cartridges and companies would charge extra for the privilege. Moreover, Nintendo's own licensing policies swallowed up a large portion of the profits, already smaller due to the lower prices for disk-based games. Piracy was pretty commonplace, despite Nintendo's security measures.
Nintendo set up Disk Writer kiosks in stores across Japan to allow gamers to purchase new disks and rewrite old disks. Considering that renting games was illegal in Japan, this was a good way to allow children to sample many games at reasonable prices. This may have worked relatively well in Japan's more densely populated urban areas, but the more rural areas may have felt left out due to the distance required to travel to get to a shop with a Disk Writer. Nintendo had to periodically service these machines with new games.
Unfortunately, this device is probably the most unreliable device Nintendo ever made. The disk had no dust cover on them, making them prone to dust. Like floppy all disks, the magnetic media can wear out over time and stray electromagnetism can make bits unreliable. In fact, I have read of people recently buying disks sealed in the box and having them fail. ROM cartridges are far more robust.
The disk drive itself has a head that will need cleaning, and the custom format means that getting disk cleaning disks will be tricky. The drive belts will become loose, can break over time or even melt, and the circumference is a custom length. Although the NES front loader cartridge connector will win no awards here, the pins can be cleaned and bent back. Nintendo must have had made a pretty penny replacing drive belts for systems out of warranty and they offered the service until 2003.
The disk system came with a RAM adapter. Inside this RAM adapter was a custom ASIC chip called the 2C33 that interfaced with the disk drive, provided the extra sound channel and came embedded with an 8KB BIOS ROM. The sound channel modulates an arbitrary 6-bit waveform. The RAM adapter also contained 32KB of RAM for Program Memory and 8KB of RAM for Character Graphics Memory. Not unlike the Starpath Supercharger for the Atari 2600, the use of RAM allowed games to split the amount they would use for code and the amount of extra RAM they could use. To load new data required reading from the disk. Reading from the disk introduced load times to Famicom players. For example, it can take 10 seconds to create a new character in Legend of Zelda and 45 seconds to load a game from the menu in Metroid, not accounting for the time it takes to flip the disk.
The disks are 3" wide, narrower than the common 3.5" disks. They are Mitsumi Quick Disks with some extra plastic on the end that is molded with NINTENDO. Real Nintendo disks are usually yellow and have no metal dusk cover, but Nintendo did release some special blue disks with metal dust covers. This acts to prevent non-Nintendo disks from being used because the drive has a mold that must fit some of the holes in that word, but this was quickly circumvented. The disks themselves can offer up to 65500 usable bytes of storage for a game on each side of the disk. However, some of that space is taken up by sychronization bits, checksums and headers, so the actual space available to the programmer is less than the nominal amount. With a cartridge, just about every byte is freely available for the programmer to use. Also, there are no load times with cartridges and if the game is larger than 64KB, no disk swapping is required. Standard Famicom cartridges could store only 40KB without additional hardware. A 128KB cartridge game has more space available to it than a double-sided disk game.
The drive itself could be powered by the included AC adapter (you can use a Sega Genesis adapter here in the US) or 6-C Cell batteries. Apparently power strips were not yet ubiquitous in Japan and there was no room left in the outlet when the TV and Famicom were connected. The batteries, beastly as they are, should last for quite a while because the disk drive's motor is not always active.
Interestingly, Nintendo had already released a keyboard for the Famicom that plugged into the Famicom's expansion port. This keyboard came with and was only used with the Family BASIC cartridges. Family BASIC saved data to the the Famicom Data Recorder, a cassette recorder that plugged into the audio ports of the keyboard. The cartridge contained only 32KB/8KB of ROM and 2KB or 4KB of battery backed RAM. Nintendo could have had their console behave more like a "Family Computer" had they released a BASIC disk, but never did so. Disk based storage is far more preferable to cassette based storage.
Most FDS-exclusive games came one disk, using two disk sides. Many of the cartridge ports only required one side of a disk, leaving the other side free for a different game. The PC-adventure style games were typically released in two parts with part 2 being released typically later than part one and require four disk sides.
One thing the FDS had going for it is Zelda no Densetsu : The Hyrule Fantasy (The Legend of Zelda overseas). No console, let alone an add-on, could ask for a finer launch title. Many game designers would be happy if they produced one bona-fide classic, but Shigeru Miyamoto produced his third indisputable masterpiece after Donkey Kong and Super Mario Bros with Zelda. Zelda offered Famicom players a unique experience. It had puzzles, tons of secrets, unique enemies, multiple items to equip and for the time what must have seemed like a gigantic world. Yet though that world was large, it was finite and almost no two screens were exactly alike. Unlike many other games, then and now, it did not force you to do things in strict sequence. As icing on the cake, when you completed the game, there was a second, harder quest thrown in for free!
To me and many other non-Japanese NES fans, the most interesting aspect of Famicom Disk System games are the games that were ported to the NES. Fortunately Nintendo released Zelda as its first battery-backup cartridge overseas. It knew it had something special on its hands, and sought to impress people with a shiny gold box and cartridge. Considering Zelda sold several million copies, they were literally on the money.
Zelda cartridge is a good port of Zelda FDS. You loose the extra sound channel, but it is chiefly used during the intro and ending credits, like most other of Nintendo's FDS games that were ported to cartridge. Nintendo did not seem to use the extra sound channel for music during gameplay but did use it for sound effects. Sound effects like Link throwing his sword and the doors opening in Metroid sound much more impressive compared to their NES counterparts.
When Nintendo ported Zelda to cartridge and released in July, 1987, they implemented a battery backed save mechanism. The battery would keep an S-RAM in the cartridge powered so it would not lose its memory when the system was turned off. It was the first NES cartridge released with a battery backed save. The next battery backed cart would be Zelda 2, released in December, 1988. Battery backed games were expensive, but far less common in the US than in Japan. Of the roughly 750 US cartridges released during the NES's lifetime, only 56 had batteries. By contrast, even though there were just over 1,050 Japanese Famicom cartridges, at least 200 had batteries. Also, every FDS game had the potential to save.
Back in the 1980s, when Japanese games were ported to the US, many had minimal text to translate. Some Japanese games used English throughout (if the game was fairly light on text) because most Japanese children would be expected to understand some English words and even simple sentences. Other games would use Japanese mostly or entirely thoughout. The more text, the less likely the port as translation cost time and made things more difficult when porting. Many of the games that were text heavy and saw ports usually had lots of "Engrish" until development companies began assigning these tasks to people who could actually speak English. This would be apparent in games with lots of text like both Zelda and Castlevania II. The Engrish in those games made many dialogues and hints seem truly cryptic.
However, games in the 1980s themselves were pretty cryptic when it came to clues. Ultima : Exodus, even before it was ported to the NES, was very terse when it came to clues. Limited disk or cartridge space and the lack of compression tended to cause text to get the clipped shrift. The FDS version of Zelda also had its obscure hints, as you can read here : http://legendsoflocalization.com/the-legend-of-zelda/first-quest/ Dracula II : Nori no Fuuin, another text heavy FDS game that was ported over to the NES as Castlevania II : Simon's Quest, also has its fair share of head-scratchers : http://bisqwit.iki.fi/cv2fin/diff
Several FDS games, including Link no Boken, Doki Doki Panic and Dracula II, when ported, used 256KB carts. The porters had more than double the space, and not all of it was taken up by the extra space needed to store English text over Japanese text. In the US version of Zelda II, each dungeon had its own set of background tiles, some bosses were redesigned and the battle music is more complex. Castlevania II has much better music than Dracula II, the percussion channel in the NES is used to better effect than the extra FDS sound channel. Super Mario Bros 2 has much more animation than Doki Doki Panic. However, Jackal has an extra stage, cut-scenes and can scroll the screen horizontally as well as vertically compared to its FDS counterpart (Akai Yousai) and the cart only has 128KB.
There can be some subtle differences between the original cart release and an FDS port. Two games that original appeared as a cart, Wrecking Crew and Excitebike used the Famicom Data Recorder (a cassette recorder) to save custom levels and tracks. When ported over to the FDS (the latter as Vs. Excitebike), they saved to disk. While Super Mario Bros. for FDS does not support saving to disk, it does have a completely different minus world (consisting of three levels) that can be completed.
Many games, when ported over to cartridge, lost their ability to save games. This includes Castlevania, Castlevania II, Dr. Chaos, Kid Icarus, Metroid, Mystery Quest and Super Mario Bros. 2., and Section Z. Castlevania II, Dr. Chaos, Kid Icarus and Metroid use passwords, and the ability to have fun with custom passwords today makes them, in my opinion, more interesting than standard save games. Of course, Japanese gamers did not have to write down these passwords and hope they did not make any errors or confuse a 0 with an O or a 1 with an l. (At least we weren't subject to the intimidating 52 character long passwords of Dragon Quest II or the insane 104 character long password of the Japanese version of Maniac Mansion). The rest allowed for continuing after you died (limited in the case of Super Mario Bros. 2).
Toward the end of the Famicom's life, there were a few ports of games that were released on Disk to Famicom Cartridge. In each case, Zelda, Akumajou Dracula and Moero Twinbee, the overseas cartridge versions were taken as the base for the reverse port and took what they could and needed from the disk versions. Cartridge Akumajou Densetsu loses saving, but gains an easy mode. Moreo Twinbee (released as Stinger in the US) also has the easy mode and retains the three player mode of the disk version, which works by plugging a controller into the Famicom expansion port.
Two FDS games, when ported to NES cartridges were given a complete overhaul. Roger Rabbit became The Bugs Bunny Crazy Castle. LJN obtained the rights to publish a Roger Rabbit NES game, so Kemco had to replace Roger Rabbit with Bugs Bunny when they released a cartridge based on the FDS game. The result was little more than a sprite hack, with Roger being replaced by Bugs and the Weasels being replaced by multi-colored Sylvesters. Crazy Castle also had Yosemite Sam, Daffy Duck and Wile E. Coyote as enemies, but they appeared far more seldomly. Roger Rabbit changes them into the Ink and Paint Club Gorilla, the Penguin Waiters from the Ink and Paint Club, and Judge Doom. The object of Roger Rabbit is to rescue Jessica Rabbit, Bugs Bunny has to rescue Honey Bunny. (This was 1989, and Lola Bunny, his modern girlfriend, was created for Space Jam in 1996).
In porting Doki Doki Panic to Super Mario Bros 2, Nintendo made major changes. The replaced the original characters entirely with Mario characters, changed the plot entirely, modified sprites and replaced music. In Doki Doki Panic, each character had to progress through the levels on their own, and the player could save the game for each world they completed with a character. For Super Mario Bros 2., Nintendo allowed the player to select from any of the four characters each time they entered a new level or lost a life, but they also eliminated the ability to save your game. Finally, to see the true ending in Doki Doki Panic, you had to complete the game with all four characters. The NES version will show you the full ending by beating the game once, but only allows you two continues. Here is a more visual and detailed depiction of the changes : http://www.themushroomkingdom.net/smb2_ddp.shtml
If you look inside a Metroid or Kid Icarus cartridge, you will see an extra RAM chip. In fact, these games use the same cartridge board as Zelda, and even have a place on them for a battery. Apparently, these games needed the flexibility of more RAM than the NES could provide. The FDS could provide more RAM (at the expense of ROM), but they needed extra RAM for the cartridge versions. It seems that Nintendo didn't want to spend the extra nickel to put in a battery or the programmer's work on the password system was too far to revert before they discovered that the games needed extra RAM. Similarly, Super Mario Bros. 2 also has an extra RAM chip, but its board does not have space for a battery.
Super Mario Bros. 2 for the FDS was not released for the NES, but was released for the SNES as "The Lost Levels" and a portion of it (Worlds 1-8 only) for the Gameboy Color as Super Mario Bros. Deluxe. It is well known that Super Mario Bros 2. FDS was rejected for being too difficult for the US market. However, there are differences between the original FDS version and the SNES remake. The SNES cart remembers the level saved, unlike the FDS version which only remembers the world. World 9 requires the player to complete every level of Worlds 1-8 without warping, but the FDS only gives you one life and loops back to 9-1 after you beat 9-4. This is closer to the original minus world concept of Super Mario Bros. In the SNES version, you go to World A-1 when you beat 9-4. Also, the player must beat the game eight times in the FDS version and press A on the title screen to progress to World A-1, whereas you only need to complete Would 8-4 (with or without warping) to get to World A-1. Thus the FDS game does save how many times you beat the game.
One annoyance with FDS games is that, unless you obtain a pristine, new-in-box copy of a game, you are likely going to be saddled with somebody's old saves. Most NES games allow you to delete old saves and those deletions will stick If the NES game does not, the game will be restored to its pristine condition when the battery fails or is removed. While the two Zelda games allow you to restore the game to a pristine state with no save games, the rest of the games mentioned here do not. Zelda and its sequel will write to disk if you kill a game or start a new game, but the others will only write to disk if you start a new game. Therefore you will always have at least one character on your disk.