Transcribed from Issue #20 Mar/Apr 1991 Pgs.28-31 of Nintendo Power By Nick M WHY YOUR GAME PAKS NEVER FORGET ____________________________________ Starting in this issue, we'll include extra information about games in a data box. Some of the info cover memory sizes and configurations-information you can't get anywhere else. In the following pages, we'll tell you everything you need to know about ROM's, RAM, MMCs and more. IT ALL BEGAN WITH NROMS Let's start at the beginning. Computers like the NES Control Deck are impressive machines. You can do everything from designing spacecraft to rescuing Princess Toadstool from the evil clutches of King Koopa. But even the most powerful super computers are useless without programs to run them on. Game Paks, of course, are really just programs that your control deck can run. As you also probably know, programs consist of stored bits of data, or memory, in the form of numbers. What you might not know is how that memory is stored by your Game Paks, or that different or that different game use different types of components. Why all the differences? Because the NES was designed so that the latest technology could be used in each new generation of Game Paks. It's more like an RC car. When a faster motor comes out, you buy one and slap it into your old racer. Thats how games can get bigger and better while your Control Deck stays the same. For several years in a row, the max memory size on silicon chips has doubled every year. Back in '85, the 256 X 64 K of SMB was considered big. In 1985, the first NES games appeared using the NROM. ROM, which stands for Read Only Memory, is like a book with words that can't be changed or added to. By today's standards, the two microchips- one for the program and one for characters- were rather small. The program ROM's maximum memory size was 256 K and Character ROM's max memory was 64 K Of course small is a relative term,. 256 K means 256,000 bits of information. Actually one K equals 1024 bits, so 256K is a bit larger than 256,000 bits. But size isn't everything. Down To Basics __________________________________ | NROM Game Pak | | [CHR] [PRG] | |__________________________________| Data \/ /\ Address \/Data /\ Address | | | | ____ | _____ | __________ | ____ | _____ | \/ /\ \/ /\ | | [Video RAM] [Work RAM] | | /\ /\ /\ /\ | | \/ | \/ | | | [ CPU ]<-------->[ PPU ] | | NES Control Deck | |_________________________________ | STEPPING UP WITH THE UNROM It wasn't long before Nintendo started looking for ways to expand the capabilities of the NES. The UNROM was one result. The UNROM Game Pak has a PRGROM and a RAM chip RAM means Random Access Memory. It's a place to store information until it's needed, like a filing cabinet. Background and moving object characters for the current area of the game are stored in RAM, which is a more versatile method than storing everything in a ROM. The UNROM allows greater memory size and a process called Bank Switching, which is described below. The RAM Works __________________________________ | UNROM GAME PAK | | [RAM] [PRG] | | /\ /\ /\ | | ___| __|_________________ | ________ | Data | | Address | ___ | __ | ________________ | _________ | | | | | | [PPU]<--------------------->[CPU] | | NES Control Deck | |___________________________________| The UNROM was used for Pro Wrestling because of the number of opponents required by the game. MMCs: CUSTOM CRAFTED FUN To understand Bank Switching, picture a game as one page in a story book. The first thing you'll notice is that you canonly write so much on a single page. A one page story might be okay, but if you want to expand the story, you'll need to add more pages. It's the same with games. Program size is limited, but you can add programs to the chip. Bank Switching allows you to have several programs in one chip. When a new area of the game is reached, you'll automatically switch to the appropriate program, which is useful in big game with many variations or worlds. An Even bigger revolution came in the fore of Memory Management Controllers, or MMCs. An MMC is a custom designed set of circuits in a chip that allow specialized functions. Some of the circuits, which are aslo called Logic Gates, increase the speed or efficiency of computations. Others direct the program into specific locations in memory, sort of like doors that you open if you have the right key, The UNROM used off-the-shelf Logic Gates, which took up alot of space. MMCs are more compact, cheaper, and they also allow larger program and character memory size. some of the other benefits include being able to scroll in differen t directions and the use of battery backed up RAM that can save your game progress from one play session to the next. When the first wave of MMCs hit, they mad quite a splash. The Legend of Zelda, Metroid and Kid Icarus opened up vast new worlds of NES fun and challenge. Most new games today use MMCs, and newer and better MMCs are under development, all the time. On the next page you'll find an encyclopedia of MMcs currently in use and some of their special features. Games such as Kid Icarus and Zelda became possible with the introduction of specialized MMCs. It's Only Logical Logic Gates A C D __|__|__|__ __|__|__|__ _| |_ B _| |_E _| |_ _| |_ _| |_ _| |_ |_________ | |_________ | | | | | | | F G I __|__|__|__ __|__|__|__ _| |_ _| |_ _| |_ _| |_ _| |_ _| |_ |_________ | H |_________ | J | | | | | | F MMCs A B C D E __|__|__|__|__|__ | | | MMC | |______________| | | | | | F G H I J Logic Gates are like a buffet dinner. Your choices are great, but if you only want dessert, everything else just takes up space and is wasted. With MMCs you jump staright to the dessert table. MMC ENCYCLOPEDIA MMC1 The first MMC chip to be used for the NES is still the most popular today. Many of the classic games like Legend of Zelda and Metroid became possible only after the MMC1 was developed. In Metroid for instance, much of the challenge and excitement comes from the ability to scroll both horizontally and vertically. That kind of change of pace keeps a game fresh and exciting all the way to the end. Extra memory can also translate into more worlds and enemies. The complexity of some of the MMC1 games has kept them in the Top 30 for years. MMC2 To date, only one game has been designed for use with the MMC2, but that game is one of the biggest hits of all time. Punch-Out! is unique in several ways. First, the opponents are big characters. You can actually see expressions on their faces or subtle movements of their feet or hands, which are often signals to throw a punch. Second, the game program has a great number of variations, which requires extra memory. MMC3 Along with additional memory size, the MMC3 allows some great innovations like the split screen scrolling in Super Mario Bros. 3 The scoreboard at the bottom of the picture is actually a second screen which stay put, even as Mario sprints from left to right. It's made possible by a timer function that was specially built into the MMC3. Scrolling at an angle is also possible as seen in NES Play Action Football. The MMC3 is currently a hit with programmers and players alike. SMB 3 is the biggest NES hit ever. MMC5 The latest advances, including an improved battery back up system, better color definition and partial screen scrolling are mad possible by the MMC5. Some of these improvements are due to costomized mathematics module that frees up the Control Deck's CPU from some repetative functions such as running an internal clock. It also allows vertical split screen scroll, which mean you can have a side bar of information while the scrolling action of the game continues. Memory size for the MMC5 shoots up to 8 Megs. With a single meg equaling 1,048,576 bits, that's a lot of memory. As for saving games, with the MMC5, you won't have to push RESET while pushing POWER when you want to quit. ____________ | /\ [F | Verticle | | [I | Split Screen | | [X | Scrolling | SCROLL [E | |_________ [D | _______ MMC5 Color Area ------ |_+_|___| Regular Color Area------|___|___| To see how color definition is improved in games like Castlevania ]|[, Study the color area illustration above. Each Color Area can have up to four different colors, but on the MMC5 the Color Area is smaller. In the same space where older games had one Color Area with four possible colors, the MMC5 allows four Color Areas with 16 possible colors. BATTERY PAKS In the early days of NROMs, if you wanted to finish a game you had to do it during one play session. That limited the complexity of games, because no matter how good a game is, players are only human and have to stop to eat or sleep every so often. In a RAM chip, where the game information is stored, memory takes the form of switches they are either turned on or off. If a switch is on it represents the digit one, and if it's of it represents zero. Together, the ones and zeroes make up numbers, which is how computer information is stored, without the power turned on, all the switches are deactivated and the information is lost. By putting a battery in the Game Pak, game data can be stored as long as the life of the battery-about five years. COMPRESSION Compression is a programming technique that allows a programmer to pack as much information as possible into a limited memory space. Imagine that the Tetris blocks shown below are each a program. You can see that the first example takes up more space than the second, even though they both contain the same programs. this is one reason why memory size alone doesn't tell the whole story. You Can Be A Know-It-All What's in the new Power Data Box? The first number is program memory size, the second shows character memory size. The M stands for Megabits. The type of MMC used and the size of the Work RAM are also shown. PUTTING IT ALL TOGHETHER BEHIND THE MASK ROM One of the most common misconceptions about NES games is that you can record and erase them like tape cassettes. Erasable/Programmable ROMs do exist (EPROMs and PROMs), but they are very expensive and are chiefly used for NES research and development. To reduce costs, NES Game Paks use what is called a Mask ROM. The process begins by converting the game program into an actual integrated microcircuit. Using a photographic process, the circuit is reduced to thin silicon wafers, so the game information isn't just stored in the chip, it's part of the chip. Then the wafers are sandwiched together and attatched to connector pins. Below are the two most common configurations of Mask ROM chips. The major difference is that the Flatpack chip is smaller and more compact and can fit into Game Boy Paks. FLATPACK CHIP _|_| _| _|_ __| |__ __| |__ __| ROM |__ __| |__ |________| | | | | DUAL IN-LINE CHIP __|__|__|__|__|__ | | | ROM | |______________| | | | | | THE BOTTOM LINE As you've seen, Game Paks are not all created equal. Some have special built-in features that allow greater variety in game design. But the measure of any great game is not memory size of whether it uses a MMC1 or MMC5. The real test is whether or not it's fun to play. Dr.Mario, a 256 K x 256 K game, requires less memory than many other new games. But once you start playing, it's almost impossible to stop. Remember, it's the stuff that memory is made of that counts.