List of Super NES enhancement chips
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As part of the overall plan for the Super Nintendo Entertainment System, rather than include an expensive CPU that would still become obsolete in a few years, the hardware designers made it easy to interface special coprocessor chips to the console. Rather than require a complicated upgrade procedure found in the IBM PC Compatible world of computers, these certain enhancement chips were included inside the plug-in game cartridges themselves if needed for a specific game. This is most often characterized by 16 additional pins on the cartridge card edge.[1]
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[edit] Super FX
The Super FX chip is a supplemental RISC CPU developed by Argonaut Games that was included in certain game cartridges to perform functions that the main CPU could not feasibly do.[2] It was typically programmed to act as a graphics accelerator chip that would draw polygons to a frame buffer in the RAM that sat adjacent to it.
In addition to rendering polygons, the chip was also used to assist the SNES in rendering advanced 2D effects. Super Mario World 2: Yoshi's Island used it for advanced graphics effects like sprite scaling and stretching, huge sprites that allowed for boss characters to take up the whole screen, and multiple foreground and background parallax layers to give a greater illusion of depth.
This chip went through three revisions, first starting out as a Chip-on-Board epoxy glob-top in the earliest Star Fox cartridges, labeled as Mario Chip-1. Within a year, the chip was given a more conventional surface-mount package, commonly called the Super FX (no number). Both versions are clocked with a 21 MHz signal, but an internal clock speed divider halved it to 10.5 MHz. Later on, the design was revised to become the Super FX GSU-2; this, unlike the first Super FX chip revision, was able to reach 21 MHz. All versions of the Super FX chip are functionally compatible in terms of their instruction set. The differences arise in how they are packaged, their pinout, and their internal clock speed.
[edit] DSP
This fixed-point digital signal processor chip allowed for fast vector-based calculations, bitmap conversions, both 2D and 3D coordinate transformations, and other functions.[3] Four revisions of the chip exist, each physically identical but with different microcode. The DSP-1 version, including the later 1A and 1B bug fix revisions, was most often used; the DSP-2, DSP-3, and DSP-4 were used in only one title each.[4]
[edit] DSP-1
The DSP-1 is the most varied and widely-used of the SNES DSPs, appearing in over 15 separate titles. It is used as a math coprocessor in games such as Super Mario Kart and Pilotwings that require more advanced Mode 7 scaling and rotation. It also provides fast support for the floating point and trigonometric calculations needed by 3D math algorithms. The later DSP-1A and DSP-1B serve the same purpose as the DSP-1, however, several bugs were corrected in these later chips.
[edit] DSP-2
The DSP-2 can only be found in the SNES port of Dungeon Master. Its primary purpose is to convert Atari ST bitmap image data into the SNES bitplane format. It also provides dynamic scaling capability and transparency effects.
[edit] DSP-3
An assistant chip used only in one turn-based strategy game for the Super Famicom in Japan titled SD Gundam GX. The chip assisted with tasks like calculating the next AI move, Shannon-Fano bitstream decompression, and bitplane conversion of graphics.
[edit] DSP-4
A DSP used in only one game cartridge, Top Gear 3000. It primarily helped out with drawing the race track, especially during the times that the track branched into multiple paths, which was a unique feature of this type of game at the time.
[edit] S-DD1
The S-DD1 chip is a powerful ASIC decompressor made by Nintendo for use in some Super Nintendo Entertainment System Game Paks.[2] Designed to handle data compressed by ABS Lossless Entropy Algorithm, a form of arithmetic coding developed by Ricoh, its use was necessary in games where massive amounts of sprite data had to be compressed with a 32 or 48 megabit data limit in mind. This data is decompressed on-the-fly by the S-DD1 and given directly to the picture processing unit.
The S-DD1 mediates between the Super NES's core CPU (the Ricoh 5A22) and the game's ROM via two buses. However, the controlling 5A22 processor may still request normal, uncompressed data from the game's ROM even if the S-DD1 is already busy with a decompression operation. This form of parallelism allows sprite data to be decompressed while other types of data are quickly passed to the main CPU.
Star Ocean and Street Fighter Alpha 2 were the only games that used this chip.
[edit] SA-1
The SA-1 was used in a number of SNES games, including the popular Super Mario RPG: Legend of the Seven Stars. Similar to the 5A22 CPU in the console, the Super Accelerator 1 (SA-1) chip contains a 65c816 processor core clocked at 10 MHz, a memory mapper, DMA, decompression and bitplane conversion circuitry, several programmable timers, and CIC region lockout functionality.[2] The SA-1 as used in the SNES is not a slave CPU for the 5A22; both can interrupt each other independently.
[edit] SPC7110
A data decompression chip used solely by Hudson in a few games. Far East of Eden Zero also contains a real-time clock chip accessed via the SPC7110.[2]
[edit] Cx4
The Cx4 chip, often incorrectly called the C4, was used to handle the wireframe effects, perform general trigonometric calculations, and to help out with sprite positioning and rotation in Capcom's second and third Mega Man X series games.[2]
[edit] OBC-1
A sprite manipulation chip used exclusively in the Super Scope game Metal Combat: Falcon's Revenge, the sequel to Battle Clash.[2]
[edit] ST010
A chip created by Seta for general functions and handling computer cars' AI in F1 ROC II: Race of Champions.[5]
[edit] ST011
A chip created by Seta for mostly AI functions in Hayazashi Nidan Morita Shougi. Likely uses the same microcontroller core as the ST010.[6]
[edit] ST018
A chip created by Seta and used in Hayazashi Nidan Morita Shougi 2.[6]
[edit] S-RTC
A real-time clock chip used in one game, Dai Kaiju Monogatari 2.[2]
[edit] SGB CPU
This chip was used only inside the Super Game Boy peripheral and possessed a core identical to the CPU in a regular handheld Game Boy. Because the Super NES was not powerful enough to use software emulation to simulate the Game Boy, circuitry equivalent to an entire Game Boy had to sit inside of the cartridge.[6]
[edit] MegaChips MX15001TFC
This chip was made exclusively for Nintendo Power cartridges. The cartridges were equipped with flash ROMs instead of mask ROMs, and were designed to hold games downloaded from specialized kiosks for a fee. The chip managed communication with the kiosks to download ROM images, and provided an initial menu to select which of the downloaded games would be played. Some titles were available both in cartridge and download form, while others were download only. The service was closed on February 8, 2007.[7]
[edit] References
- ^ anomie. Anomie's SNES Port Doc (text). Retrieved on 2007-07-13.
- ^ a b c d e f g (2007-05-01) Snes9x readme.txt v1.51. snes9x.com. Retrieved on 2007-07-03.
- ^ Overload (2006-05-29). Digital Signal Processing. Overload's Puzzle Sheet. Retrieved on 2007-05-09. Refer to the command summaries for all four DSP versions.
- ^ Nach; Moe, Lord Nightmare. SNES Add-on Chip information. Retrieved on 2007-05-09.
- ^ Overload. ST-0010. Overload's Puzzle Sheet. Retrieved on 2007-07-03.
- ^ a b c ZSNES v1.51 Documentation. Retrieved on 2007-07-03.
- ^ Nintendo Power. N-Sider.com. Retrieved on 2007-07-03.
