Tag: nes

Nicole Express on Twin Famicom Compatibility with Guardic Gaiden

Nicole Express is so knowledgable. How many blog posts have you seen about an obscure hardware issue, itself with obscure hardware, and the Japanese version of one specific cult game? Which the writer tested herself with her own unit and cartridge? Then went in to investigate herself with a freaking multimeter? Whaaa?

Nicole’s two Twin Famicoms

I won’t keep you waiting for the link: here it is. And here is my grossly simplified summary, intended to inspire you to go to the original article, if you have the time, and get all the deets.

Guardic Gaiden, known in the US as The Guardian Legend, uses a weird trick to put its status bar at the bottom of the screen, instead of, as usually seen in an UNROM game, at the top. To create a fixed status window requires stopping whatever the processor is doing at a very precise time while the display is being drawn to the TV, and then changing some PPU registers to display the status.

Guardic Gaiden’s title screen

More complex and versatile mappers, like the MMC family, have the ability to trigger interrupts at specific screen lines, but Guardic Gaiden/Guardian Legend doesn’t use an MMC. It doesn’t even have a raster line counter, so the game simply doesn’t know where on screen the raster beam is drawing.

There are still lots of games on the system that have status windows, even with MMC chips. The PPU has a built-in feature called Sprite 0 Hit, where the chip can signal when Sprite 0 (of the system’s 64 sprites) is being drawn on top of non-transparent background data. So what older games commonly do is put Sprite 0 in an unobtrusive place at the bottom of the status window at the top of the screen. When the Sprite 0 Hit register indicates a collision, the code knows it’s time to set up the PPU to display the main portion of the game screen.

There is a really big problem with this setup, though. Sprite 0 Hit doesn’t trigger an interrupt. It doesn’t stop the code to let it switch the graphics. It’s not even proper to say it “sends a signal.” It’s up to the code to check if Sprite 0 Hit has been triggered. If it has, then it’s time to set the scroll register to the right place, and maybe switch to the proper background tileset, and do whatever else needs to happen, and the code can then be off to run essential game logic, the actual game part of the game.

If it hasn’t… then, the code has to check again, and immediately. And if it hasn’t triggered then, to do it again. It has to literally check as quickly as it can, because if it delays in its check, the game screen might not get set up at the right moment, which will be perceptible as the bar straying down one extra line that one frame. Not the end of the world, but it looks glitchy. And this code will be running every frame, so if it strays down once, it might do it again, which is a more perceptible glitchiness.

Sprite 0 is set to trigger its hit at the top of the screen, because the code won’t have to spin its wheels checking the hit over and over. It wastes time, but not that much. This is why UNROM games put their status lines, with the score, timer, health bar and life counters, at the top of the screen.

Well, The Guardian Legend is an UNROM game, and maybe because creators Compile wanted to show off, they decided they’d put the bar at the bottom of the screen. And yet, their game doesn’t waste most of each frame just in maintaining the status bar.

How? And what does that have to do with the Twin Famicom? For that I’m going to direct you to Nicole Express’ blog post. May you find it as fascinating as I did!

Nicole Express: Is the Twin Famicom Flawed? The Case of Guardic Gaiden

NESHacker’s Guide to the NES Hardware

More and more I find I should do a blog search to make sure that I haven’t posted something before, and my search for this video didn’t find it. It did find our link to the Copetti Site’s discussion of various console architectures, and a separate link specifically to their explication of the SNES’ construction, but not this particular video from NESHacker, so it’s fair game. Post! (zoop)

It’s only about nine minutes long so you can guess that it doesn’t go into deep detail. Essentially the NES is split into two parts, the CPU and its memory, and the PPU graphics chip and its own memory. A lot of classic consoles and microcomputers had to take special measures to support their display, which often ended up being the most complex part of the unit. Think about it: you have what amounts to a deluxe broadcast character generator right there in a box on your desk, shelf or floor, with lots of extra bells and whistles besides. (In fact, home computers were often used to generate current events channels for local cable companies, and an Amiga was essentially the basis for the old Prevue Guide channel.) It’s like a tiny special-purpose, single-receiver TV station just for your own use.

Graphics hardware is extremely timing sensitive. It has to generate the signal for your TV to display according to standardized picture generation requirements, so special requirements are often necessary. In the Commodore 64, for instance, the VIC-II graphics chip has the power to actually put the 6510 CPU to sleep, so it can have unrestricted access to the computer’s memory, without fear of bus conflicts, when it’s needed. This reduces the overall speed of the processor by a bit, and it’s why C64s turn off the screen when loading programs from cassette tape, in order to keep the CPU timing consistent relative to the data being streamed in off the tape.

The NES gets around this by giving the PPU RAM and address bus for its own exclusive use, and to put stuff in it the CPU has to use the PPU as an intermediary. And what’s more the NES exposes both the CPU and PPU’s address busses through the cartridge connector (which is why it’s got so many pins), allowing carts to supply dedicated ROM and RAM to both chips.

Even though it’s just a high-level overview, I found it a worthwhile use of those nine minutes, and you may very well enjoy it too.

NES Hardware Explained (from NESHacker, on Youtube, 9 minutes)

Sundry Sunday: Steamed Hams, But It’s An NES Game

Sundry Sunday is our weekly feature of fun gaming culture finds and videos, from across the years and even decades.

So despite the fact that you likely already know all of this, I still feel like I have to explain it all for people who might not have soaked their brains in US popular culture, yet still care enough about video games that you’re reading Set Side B. Let’s get it out of the way as quickly as feasible.

Premiering December 17, 1989, The Simpsons has been on the air for approaching 35 years. We in the United States are going to have to come to terms with the fact that it’ll probably be the reigning television fact of our lives. When it began, the NES was still the hot game system, and that was eons ago.

Premiering in the 7th season, during the time when most people still agreed The Simpsons was the best show on television, was the episode 22 Short Films About Springfield, in which the writers created a loosely-connected sequence of miscellaneous stories about the many side characters in The Simpsons. One of those stories was “Seymour and the Superintendent,” where Bart’s principal hosts his boss Superintendent Chalmers to a home-cooked meal, but due to a sequence of comical events serves him Krusty Burgers instead, covers it up in a variety of unlikely lies, and nearly burns down his house. Colloquially this has become known as “Steamed Hams,” after one of the lies Principal Skinner tells.

In 2017, a popular meme went around the internet in which people remade, remixes, or otherwise re-did that story, alone of all of them in the episode, the season, and among the long long run of the show.

In fact, those memes are still being made, and this post’s subject is one of them. It’s a video simulating what a Steamed Hams game would have been like if it were made in the style of the Bart vs the Space Mutants and Bart vs The World games on the NES. It was made by Penney Pixels, it’s four minutes long, and it’s here, and here:

There is an actual game version of the Steamed Hams, of which a playthrough is recorded here, and can be downloaded here. There’s another version of Steamed Hams too, and it can be played on GameJolt here. Both of those are adventure games.

I thought Steamed Hams had come up here before, but a quick search didn’t find anything, so I’ll just leave it at this. I’m sure in the next 35 years there will be hundreds more game versions of Steamed Hams. Maybe after all that time, I’ll be able to bring myself to mention it here again.

Computing Pi on a NES

Today’s link is to a madperson who explains how to compute digits of pi on a NES’s 6502 to an arbitrary length. As you do. Along the way it explains how to multiply and divide in binary on a processor without hardware support. It’s around nine minutes long, but if you want a machine to get to the end of pi it’ll probably take a tad bit longer.

We link to such a variety of things here. Sometimes we post light videos where someone has Kirby do funny things. Sometimes we show explainers that explain how to do arithmetic on old processors. I presume that you’ll take from these what you want, and leave the rest to the crazy people, by definition the people who are not you. I understand.

Youtube Series: Inside the Famicom

It’s only two episodes in, but this series from the Youtube channel What’s Ken Making is already really interesting, with episodes averaging at around 16 minutes each. The first part is titled “The Design of a Legend,” which doesn’t really grab me much, but the second is about the main processor, “The 6502 CPU,” which Ken admits near the start isn’t exactly accurate. The Famicom/NES’s processor isn’t precisely a MOS 6502; it’s a Ricoh 2A03 in NTSC territories, and a 2A07 in others. The 2A03 is licensed from MOS, but lacks the original’s Binary-Coded Decimal mode, and includes the Famicom/NES’s sound hardware on-die.

Episode 1 (15 minutes):

Episode 2 (17 minutes):

That removed BCD feature. Why? The video notes that the circuits are right there within the chip, but have been disabled by having five necessary traces severed. The video notes that the 6502’s BCD functionality was actually patented by MOS, and asks, was the feature disabled because of patent issues? Was Ricoh trying to avoid paying royalties?

Reverse Engineering the 6502

This is a 52-minute talk from 2010, from the 27th Chaos Communication Congress in Berlin, Germany (the talk is in English), presented by Michael Steil of Visual 6502, which successfully reverse engineered the venerable 6502 microprocessor, a chip used, in one capacity or another, in one form, or another, in all the Apple, Commodore and Atari microcomputers, the BBC Micro, the Atari 5200, in a modified from the Atari 2600 the NES, and countless arcade games, as well as in other places.

The talk is intended for a technical audience… literally. When the speaker asks who in the audience has coded in assembly before, practically everyone raises their hands. It’s recognized that we at Set Side B veer wildly between the most surface-level populist material and in-depth treatments for those with gigantic capacities for technical discussion and the attention span of a Galapagos Giant Tortoise. We like to think this is charming, and will listen eagerly if you tell us that you agree.

Anyway, here is that talk. I already mentioned that it’s 53 minutes. If that’s too long, there’s a speed-up function on Youtube. If that’s too technical, well, I don’t know how to help there. Maybe a read through pagetable.com’s documentation on the 6502. Oops! I’ve made it worse, haven’t I. Well, if you like, you might console yourself that the 6502 is really a simple processor to learn to code in. I’ve done it myself! There’s no memory management, there’s only three general-purpose registers, the stack is fixed in place, and all opcodes are one byte. It’s so simple that an extremely motivated child could learn it. Guess how I know?

27c3: Reverse Engineering the MOS 6502 CPU (Youtube, 53 minutes)

Here’s a description of the talk from the conference web site.

Hardcore Gaming 101 Covers Snake’s Revenge

Hardcore Gaming 101 is one of the most important game history sites on the internet, and site creator Kurt Kalata writes on a wide variety of games for consoles and computers alike. Recently they’ve been on a Metal Gear kick, and that means covering the black sheep of the series, Snake’s Revenge.

Snake’s Revenge is the forgotten Metal Gear game, an NES sequel made without Hideo Kojima input, to the NES port of Metal Gear that he also had nothing to do with. It has a reputation for being terrible, but that’s really unmerited. As Kurt Kalata notes, while it has its flaws, is ignored by later Metal Gear games, and it has a story based on the manual scenario for Metal Gear written by Konami’s crazy American writing staff*, it’s technically proficient and has good music.

Yep, it’s the Metal Gear with side-view segments.

You can, and should read it for yourself, here.

* The American manual for NES Life Force says that the evil planet-eating monster Zelos was the proud progeny of “Ma and Pa Deltoid.” In the description of Dracula’s Heart in the manual for Castlevania II, it warns: “Careful! The heart attacks.” These were not means isolated occurrences from Konami’s US staff.

Sharopolis Looks Into NES Technical Feats

Youtuber Sharopolis has a 20-minute video up examining several specific NES games and how some unexpected tricks were pulled off in each: Rescue: The Embassy Mission, Crash and the Boys Street Challenge, Castlevania III and Jurassic Park. I love learning about how developers overcame hardware limitations, and if you’re reading this, I’d wager there’s a good chance you do too!

Sundry Sunday: Gyruss Themes

Sundry Sunday is our weekly feature of fun gaming culture finds and videos, from across the years and even decades.

While there are examples of excellent music from the classic era of arcades (Frogger comes immediately to mind), I don’t think there is much that can equal that of Gyruss’ arrangement of Bach’s Tocatta and Fugue in D Minor. Here it is, isolated from the rest of the game’s soundtrack, from Youtube uploader StyleK226 (1 1/2 minues):

Wikipedia tells us that the arcade arrangement is reminiscent of a version of the song from the British band Sky, titled just “Toccata” (4 1/2 minutes):

If you only know Gyruss from the NES port, you might be surprised that it’s an almost entirely different arrangement from the arcade version! Maybe it was changed because of the similarity to Sky’s version. Some people prefer that one, it’s got a bit more variety, although I think the arcade’s is a bit better. Judge for yourself (3 minutes):

The Toccata is only used for the intro and the first warp on each planet, which is a bit of a shame, the rest of the music isn’t bad, but it’s not Bach. In Japan, Gyruss was a Famicom Disk System game. The FDS had extra sound hardware, and the result is an upgraded version of the NES soundtrack (14 minutes in all):

There’s been a number of fan versions of the Gyruss soundtrack, although most of them seem to be inspired by the NES port rather than the arcade original. Here’s a metal medley of that particular musical mutation (3 minutes):

As commenter @Fordi says, “What I love is that Intro / Stage 1 is a genre cover (metal) of a game’s adaptation (Gyruss) of a genre cover (Sky – Toccata) of classical music (Toccata and Fugue in Dm).”

Chrontendo 64

Dr. Sparkle is back with the 64th installment (Youtube, 55 minutes) of his quest to review every NES and Famicom game. He’s pretty far in! In about ten episodes, he figures he’ll reach the launch of the Super Famicom, which won’t be the end of his journey but will probably mean he’s in the home stretch.

In the meantime, ten games from 1990 are in this episode. They are:

Puss ‘n’ Boots: Pero’s Great Adventure – Technically a retread of a previously-covered Japanese game, this version has substantial differences so Dr. Sparkle decided to cover its U.S. version separately. A very easy game until the last stage where it jumps in difficulty, and then the final boss is absurdly hard. Dr. S expresses confusion why a game made to be so easy that it’s obviously intended for young children would become nearly impossible right at the last second. Personally, I suspect it was done because NES game publishers were terrified of the game rental market.

Wit’s: A Japan-only release, this is basically a de-luxe version of Snake, where your enemies have special abilities that you have to account for. Suprisingly, it’s an arcade port!

Captain Tsubasa Vol. II: Super Striker: A weird RPG take on Soccer, published by Tecmo and based on a manga and anime series. Instead of controlling a player or players completely in real time, the action pauses frequently and asks you what to do. The main screen is mostly animations down on the soccer field. It’s a unique take on soccer, but it’s not the only one: this is the second game to play like this on the Famicom. The Captain Tsubasa game series continues even today: the most recent releases, Dr. Sparkle tells us, are on PS4 and Nintendo Switch, although I don’t know if they take the menu-based RPG approach.

Jyuouki: This is simply a licensed Famicom port of Sega’s Altered Beast, and a pretty bad one at that.

Mahjong G-Men: Nichibutsu Mahjong III: Yet another Mahjong game, although with some interesting features, if you’re into Mahjong. That’s not Mahjong Solitaire, a.k.a. Shanghai, the Activision (and formerly PLATO) computer game where you remove tiles in matching pairs from a tableaux, but the Chinese Rummy-like game using tiles instead of cards. It also has a weird Tetris-like subgame involving Mahjong tiles.

The Pennant League: Home Run Nighter ’90: Yet another Famicom baseball game.

Dr. Mario: The classic Nintendo puzzle game! I always thought it was a bit inferior to Tetris, but then most games are, and that didn’t stop me from playing a ton of it long ago.

Pictionary: Based on the board game, and coming from infamous American NES publisher LJN. Dr. Sparkle is a bit harsh on developer Software Creations, but I think this effort looks pretty well-made to me. It’s not a classic, and it’s actually not really so much Pictionary as a kind of variation on the theme, where players play mini-games to reveal parts of a drawing and then try to guess what the drawing is of. It looks much like one of Rare’s many game show and board game adaptations and creations, and in fact if it weren’t for the Software Creations credit I’d have assumed that Rare made it.

Bigfoot: From Acclaim and developed by Beam Software. It’s fairly well polished for a Beam Software title, but has some weird ideas to it, including a weird control scheme for the events that involves tapping left and right on the control pad. I think the idea has a bit of merit, but that it was probably the wrong place to use it. A Bigfoot game would mostly be bought or given to kids, who would be the absolute last demographic you should expect to master a non-standard control scheme. I’m not one of those people who thinks making a game that goes about its play differently than most other games is always a terrible idea (see: most of what I’ve ever written about roguelikes), and I can kind of see why they did it, trying to make a race game that’s more than just holding to the right. It probably could have used a bit more iteration though.

Snake Rattle ‘n’ Roll: A game from Rare that they actually put a lot of effort into, and it shows. And some people really like it, it’s definitely got a cult following. Dr. S isn’t part of it, due to the difficulty of getting used to SRnR’s isometric style. I think what happened was, they had these routines laying around that they used in implementing NES Marble Madness, and decided to do another game that controlled in that kind of way. I think the game was poorly suited to a digital control pad; if it were controlled with an analog stick, or at least a digital control where diagonal movement is easier, I think it’s possible that some people who hate Snake Rattle ‘n’ Roll might be able to enjoy it better.

Anyway, here is the whole episode, start to finish:

A Guided Tour of the NES

This tab has been open on my browser for literally months, so I’m finally excising it from the bar….

A while back the site HackADay did a teardown of the NES, going through how to take it apart and reassemble it, and going through some of the elements of its assembly. It doesn’t go into a lot of detail, but that lets it be fairly short, at only nine minutes.

NES Hardware Explained (HackADay post, Youtube video)