Saturday, April 16, 2022

Mastering the Sega Master System

The Sega Master System was Sega's first major attempt to market and sell a home video game console overseas.  Its Japanese predecessors, the SG-1000, the SC-3000, the SG-1000 II, and the Mark III, were not very successful compared to Nintendo's Famicom and similarly the US release of the Master System was not very successful against Nintendo's NES.  In the European market did Sega sell more consoles than Nintendo, thanks to Nintendo's fractured distribution system and Sega's placing the Master System as a budget console.  Sega also did extraordinarily well in Brazil whereas Nintendo floundered.  In this blog entry we will go over the various issues with the Master System and why you would want one.

Overview of the Available Consoles

If you wish to enter the world of the Sega Master System with original hardware, you have many choices.  There are generally six options , a Mark III, an SMS, a Japanese SMS, a Genesis with PBC,  an SMS2, and a Game Gear.  (Photographs shown below were taken from Wikipedia unless otherwise noted).

1.  Sega Mark III

The Mark III is Sega's first "Master System" compatible console, being released in 1985 before the Master System.  It was released in Japan, South Korea, Taiwan and uses a 44-pin cartridge connector.  It supports the Sega MyCards via a card slot and has a 24-pin expansion port.  It has two DE-9 controller ports, a power button, a pause button, a DIN-8 audio-video port providing composite video and RGB video, an RF output and a barrel-type power connector.  

Pros : SG-1000 compatible expansion slot, FM Sound Unit upgrade

Cons: Dim RGB output (requires amplification circuit), incompatibility with SMS Light Phaser, no save states on Master EverDrive X7, no reset button, FM Sound Unit's connector limits video output to composite only

2.  Sega Master System (Western)

The Sega Master System was released in the US in 1986 and Europe in 1987 and in Brazil.  Through distributors it could be found in Russia, Israel, China and other countries.  The SMS has four functional differences compared to the Mark III.  The first was the addition of a reset button, but this is a software-readable switch, not a hardware circuit.  It is up to the game how to respond to a reset button press.  The second was the use of a 50-pin cartridge port.  The third was the addition of an internal BIOS chip.  The fourth is the 50-pin expansion connector, a virtual mirror of the cartridge port.  Brazil released this version of the console twice in this form factor, with the "Master System II" differing from the original release mainly via the built-in game (Alex Kidd).  

The French version of the Master System I is a little different compared to other European Master Systems because France uses SECAM.  The French version lacks an RF modulator and only outputs RGB but requires a special SCART cable with a box that contains the circuitry to bring the RGB up to the correct specifications.  

Pros : Most common US console variant, expansion port, reset button

Cons : Built-in games rather simple compared to Master System II

3.  Japanese Sega Master System (photo courtesy of

In 1987, Sega designed the Mark III using the Master System's exterior as part of a console revamp.  The Japanese Sega Master System, in comparison to the Mark III adds a BIOS chip, an FM Sound chip upgrade, a 3.5mm port for the 3-D glasses and although retaining the 44-pin cartridge slot, a 50-pin expansion connector replaced the 24-pin expansion connector of the Mark III.  The reset button of the western versions is exchanged for a rapid fire unit.  Sega marketed an external Rapid Fire Unit for other consoles.  This version was also released in South Korea as the Gam*Boy. There is a Chinese PAL variant of this console in existence without the FM Unit, 3-D Glasses adapter but retains the 44-pin cartridge connector.  The RF modulator is external in this variant of the console and plugs into the AV port.

Pros : Built-in FM sound, 3-D Glasses Adapter and Rapid Fire, unique BIOS screen

Cons : Expensive, incompatible with SG-1000 expansion port peripherals, no save states on Master EverDrive X7, no reset button

4.  Sega Master System (USSR Version)

Until fairly recently, it was an obscure fact that the Master System was officially released in the USSR in 1990-1991, years before other consoles would be officially sold in the country.  The console was imported into the country and sold at special electronics stores.  The console was localized to the extent it output in SECAM instead of NTSC or PAL and came with a professionally translated manual in Russian.  It used a modified Model 1 shell and everything about the console was as cost-reduced as possible.  Gone is the card slot, reset button, power LED, AV output connector and the expansion port.  It has a unique mainboard and Alex Kidd as the built-in game.  Even so cost-reduced the console was no great success for many reasons.  Its price tag limited it to the wealthy and the well-connected and other games were not sold for it at that time.  When the Soviet Union fell in late 1991, so did any remaining market for the console.  Not many were made.  

4.  Sega Master System II

The Master System 2 was a smaller, cost-reduced Master System released beginning in 1990 everywhere but Japan.  Gone are the reset button, the expansion connector, the card slot and the A/V port (except in France).  The pause button is retained, and except for French models RF is the only A/V option available.  In Brazil it was released as the "Master System III Compact" and South Korea as the "Super Gam*Boy II" and the "Aladdin Boy".

Pros : Most common European console variant, built-in games are unique variants

Cons : RF only without modding, no cart slot, no expansion slot, no reset button

5.  Power Base Converter + Sega Genesis

Sega designed its next generation hardware, the Mega Drive/Genesis, to be backwards compatible with Master System and Mark III games.  It did this with the Power Base Converter, a cartridge attachment that reconfigured the Mega Drive/Genesis to act like a Master System and route the cartridge pins correctly (the Mega Drive/Genesis uses a 60-pin cartridge connector).  The Power Base Converter uses either a 44-pin or 50-pin cartridge slot, depending on whether it was intended for Japan or western countries.  The Power Base Converter provides a pause button and a card slot but not a reset button.

The original Power Base Converter only fit on Mega Drive and Genesis Model 1s.  The Master System Converter II was released in Europe to fit the Mega Drive Model 2, but it lost the card slot.  The Master System Converter II and clones are compatible with Genesis Model 2s or Japanese Mega Drive Model 2s as well as the earlier systems.  The Genesis 3 is not compatible with these converters, although the first revision (VA1) of the Genesis 3 PCB can be modded to restore Master System compatibility.

Pros : Uses Genesis as a base, card slot, no BIOS region lock

Cons : No expansion slot, no reset button, no SG-1000 or TMS video compatibility, physically limited to Model 1 systems

6.  Sega Game Gear + Master Gear Converter (Master Gear photo courtesy of Sega Retro)

Sega released its first portable console, the Sega Game Gear, in 1991.  The Game Gear was based off Master System hardware and could run Master System cartridges in "Master System" mode.  In this mode the video hardware would scale the higher resolution 256x192 Master System mode graphics to the 160x144 Game Gear resolution screen.  In this mode, the Game Gear would not be able to display the wider variety of colors it could display in its native Game Gear mode.  A Master Gear Converter or clone would be required to use Master System cartridges with the Game Gear.  Most people these days would likely use an EverDrive GG.  Certain Game Gear games are really Master System games using a Sega Game Gear cartridge and use the Master System video mode.  The start button on a Game Gear functions like a pause button on a Master System for Master System games.  

The Gear to Gear port can provide multiplayer support for Game Gear games and has a mode to act as a second controller, via a pin adapter, for Master System games.  It is also possible to use a Light Phaser via this "Master Link" cable, but you will need to mod your Game Gear to allow for 15KHz analog video output for the Light Phaser to work. The Light Phaser will not work with the Game Gear's LCD.

Pros : Portable Master System, access to Game Gear-exclusive games

Cons : Blurry Master System screen scaling, bulky Master Gear Converter plus Master System Cartridge, no reset button for Master System games, no way to use 3-D Glasses, card support requires a Card Catcher.

SG-1000 Compatibility

The Mark III was Sega's third 8-bit console, following the SG-1000 and SG-1000 II.  Also Sega previously released the SC-3000, which is an SG-1000 with a built-in keyboard and advertised as an inexpensive home computer.  The Mark III is fully backward compatible with SG-1000 games, however, the colors will not look identical when a game is played on the Mark III vs. an SG-1000.  This is because the SG-1000 uses a TMS-9918 or TMS-9929-based VDP, which generates NTSC or PAL color directly.  The Mark III and later consoles use a custom VDP which adds a more advanced graphics mode but generates RGB color.  The 15 colors the TMS can show are mapped into RGB colors, but with only 64 RGB colors available, perfect matches are not possible and colors can look garish.  Here is Ninja Princess, an SG-1000 game, as shown by an SG-1000 on the left and a Mark III on the right :

The Mark III's expansion port should work with most SG-1000 peripherals which connected to the SG-1000's expansion port.  This includes the SK-1100 Keyboard which turned the SG-1000 into the equivalent of the SC-3000.  The Japanese SMS has the same software compatibility as the Mark III but because it has a very different expansion port, compatibility with SG-1000 expansion slot peripherals is lost.

Western Master Systems cannot play SG-1000 cartridges because they use 44-pins and will fail the BIOS checks.  SG-1000 card games also cannot be played due to the BIOS checks.  The Game Gear may be able to play SG-1000 games with appropriate pin converters or via an EverDrive GG or GG X7.  The Master EverDrive X7 and EverDrive GG X7 will allow SG-1000 games to be played on western Master Systems and any Game Gear.

The Power Base Converter, regardless of its intended region, cannot play SG-1000 games because the Genesis VDP lacks hardware support for the TMS video modes SG-1000 games use.  For this same reason, the Master System game F-16 Fighting Falcon (a direct port of an MSX1 game) is also not playable in a Power Base Converter.  No video will be shown in F-16 Fighting Falcon past the title screen with a Power Base Converter.

Controllers and Peripherals

Standard Control Pad (photo courtesy of Sega Retro)

The standard controller for the Sega 8-bit consoles is a 2-button D-pad.  Sega's D-pads of this era have a poor reputation, especially compared to Nintendo's D-pads.  Sega's D-pads have no circuitry in them, they are simple carbon-pad activated switches that tie a button wire to ground when the connection is made. Sega's controller ports are compatible with Atari 2600-style joysticks, but only one button will be available.  Atari 7800 controllers use two buttons but implement the 2nd button differently, so they are not completely compatible.  

Official Sega controllers that function like the Control Pad include the Control Stick, the Mark III Joypad, the Handle Controller (functions like a Genesis 3-button controller) and earlier two button controllers for the SG-1000 & SG-1000 II. 

While Sega Genesis shares the same DE-9 connector as the 8-bit systems and the Genesis 3-button and 6-button controllers generally work well and control better than the official SMS controller, there are a few games that, unpatched, will only work with a 2-button controller:

  • Alien Syndrome
  • Asterix and the Great Rescue
  • Bomber Raid
  • Great Volleyball
  • Montezuma's Revenge
  • Penguin Land
  • Shanghai
  • Tennis Ace
  • Where in the World is Carmen Sandiego
  • Wonder Boy in Monster Land

Light Phaser (photo courtesy of Sega Retro)

The Light Phaser is the SMS's light gun but is not compatible with the Mark III due to the lack of a TH signal on pin 7 of the Mark III's controller port.  It is compatible with a Japanese Master System, but no games were released in Japan that supported a light gun (and the light gun was unreleased in Japan).  This controller requires a CRT, it will not work with an LCD.  These are the games which require or support the Light Phaser :

  • Assault City (was released in Control Pad and Light Phaser-required versions)
  • Gangster Town
  • Hang On / Safari Hunt (Safari Hunt only)
  • Laser Ghost (not required)
  • Marksman Shooting & Trap Shooting
  • Marksman Shooting / Trap Shooting / Safari Hunt
  • Missile Defense 3-D
  • Operation Wolf (not reequired)
  • Rambo III
  • Rescue Mission
  • Shooting Gallery
  • Space Gun
  • Wanted

3-D Glasses (photo courtesy of Sega Retro)

The 3-D Glasses were Sega's attempt to bring Virtual Reality to the 1980s.  The 3-D Glasses consist of the glasses themselves, which use LCD shutter-based technology to block light to one eye in sequence, and the 3-D Adaptor, which fits into the card slot.  In order to use the 3-D Glasses, you must have the a console with a card slot or a Japanese Master System.  You should be able to substitute any LCD shutter glasses with a 3.5mm connector for the official Sega glasses, which tend to break.  As the 3-D effect alternates screen images at 30Hz per eye, rather than 60Hz for both eyes, the games exhibit a lot of flicker.  A CRT is required to properly sync the 3-D glasses and preserve the 3-D effect.  These are the games which require or support the 3-D Glasses :

  • Blade Eagle 3-D
  • Line of Fire (not required, supported by holding down both controller buttons while powering on system)
  • Maze Hunter 3-D
  • Missile Defense 3-D
  • Out Run 3-D (not required)
  • Poseidon Wars 3-D (not required)
  • Space Harrier 3-D (2-D mode can be activated via reaching a high score)
  • Zaxxon 3-D (2-D mode switch via pause button on title screen)

Paddle Control
 (photo courtesy of Sega Retro)

Only released in Japan, this controller has an analog paddle knob and two buttons.  Only the Out Run games were released outside of Japan.  Here are the games that require or support the Paddle Control :

  • BMX Trial: Alex Kidd  
  • Galactic Protector
  • Megumi Rescue
  • OutRun (not required)
  • OutRun 3D (not required)
  • Super Racing (not required)
  • Woody Pop: Shinjinrui no Block Kuzugi

Sports Pad (photo courtesy of Sega Retro)

A trackball controller with two buttons, this peripheral came in Japanese and a larger North American variant.  The North American version has a switch to select the trackball or the controller mode, the latter for games which do not natively support the trackball mode.  There is also a turbo-like switch on the North American version.  The Sports Pad was supported only with the following three games :
  • Great Ice Hockey
  • Sports Pad Football
  • Sports Pad Soccer

BIOS Region Lockout and Built-in Games

Nine BIOSes were released in systems made available for wide release, beginning with the western versions of the Sega Master System.  The SG-1000s and Mark III have no BIOS.  All US/European BIOSes check whether there is a game inserted in the card, cartridge or expansion slot, then they check the cartridge header to see if a particular text string (TMR SEGA) is present, and finally they check the header to check to see if the region flag has been set appropriately.  If no game is found then the BIOS will boot into any built-in game in the console.  If the checksum function does not give the correct result, which may suggest dirty cart pins or a malfunctioning cartridge, then the BIOS will display "SOFTWARE ERROR".  If the Region flag is not set to designate an "International" cartridge, then the BIOS will run the built-in game.  

These BIOS checks will prevent SG-1000 games, most of which were made before the headers were required in cartridges, and Japanese games, due to the region flag from running in US/European consoles even with a pin converter.  

US/European BIOS v1.3 (1986)

Will display the two-note Sega splash screen, will play the Snail Maze game if you hold down buttons 1 & 2 and press Up on the Control Pad.  These consoles will display (c) SEGA 1986.  If no game is detected by this BIOS, it will show you instructions on how to get a cartridge running.  

European BIOS v2.0 (1987)

An uncommon BIOS, this acts like v1.3 but the Snail Maze game has a pair of junk tiles not displayed in any other BIOS version.  It will not lockout Japanese cartridges or cartridges without the correct header information.

Japanese BIOS v2.1 (1987)

This BIOS is exclusive to the Japanese Master System.  It will show an screen with a scrolling animated floor with color cycling and play the main theme from Space Harrier if it does not detect a cartridge or a cart is inserted.  The message is intended to tell the user to turn off the system and insert a game.  The music is unique because it uses both the built-in FM and PSG sound sources at the same time, something the Mark III cannot do.  If the BIOS finds a cartridge or card, it will boot without any screen being shown.  Unlike the US/European BIOSes, the Japanese SMS BIOS has no region checking capabilities and will not lock out SG-1000 software.

US/European BIOS v2.4 with Hang On and Safari Hunt (1988)

Will run the pack-in game Hang On/Safari Hunt if no cartridge is detected.  Can get to the Snail Maze game by using the method described for the v1.3 BIOS.  These consoles will display (c) SEGA 1988.  The built-in versions of Safari Hunt tend to have minor differences compared to the standalone cartridge versions, such as displaying a blue border instead of a black border (European Hang On carts show a blue border.)

US/European BIOS v3.4 with Hang On (1988)

Behaves identically to v2.4 except it will boot standalone Hang-On

US/European BIOS v4.4 with Missile Defense 3-D (1988)

Behaves identically to v2.4 except the change to the built-in game.  Snail Maze is not available.

US/European BIOS with Alex Kidd in Miracle World (1990)

Introduced with the Master System II, this BIOS just shows a static Sega logo with no sound.  This version of Alex Kidd has some slight changes compared to the standalone cartridge versions, such as changing the rice cake Alex Kidd eats before each level to a hamburger and swapping the attack and jump buttons to 1 and 2, respectively.

European BIOS with Sonic The Hedgehog (1991)

Found only on European Master System II consoles, this eliminated the credits display found in the standalone cartridge version of Sonic The Hedgehog.

Korean Samsung Gam*Boy/Aladdin Boy II BIOS with Alex Kidd in Miracle World

Found only in the South Korean Master System II variants.  Like the Japanese SMS BIOS, this has no region detection and will not lock out SG-1000 games.  The version of Alex Kidd built-in is unique to South Korea.

Game Gear BIOS

The original Game Gear consoles had no BIOS.  At some point in the mid-90s, Sega silently released a BIOS that will perform a check of the cartridge for the copyright text string and lock up and do nothing if the string is not found.  When Majesco obtained the rights to re-release the Game Gear in the late 1990s, the BIOS would show a blue screen with white text with the words "PRODUCED BY OR UNDER LICENSE FROM SEGA ENTERPRISES LTD" if the cartridge passed the check and leaves the screen turned off if it does not find the string.  

NTSC & PAL Compatibility

Because the Master System was more successful in Europe than in the United States or Japan, there were many more games released for the European market.  Master System games do not have software lockouts between any region other than Japan versus the West.  A game released in Europe could run on a US Master System or a Brazilian Master System.  Most European games run just fine on a US Master System, and those few (3) USA exclusives should run fine on a European console, just slower at 50Hz vs. 60Hz.

There are a few games which will only run correctly on a PAL system, but they are relatively few in number (23) and many are still playable.  Most may run correctly in a PAL Mega Drive with a Power Base Converter, but the Genesis does not implement the "extra-height" mode that Codemasters' SMS games use.  A few other games that have incompatibility issues on certain systems can be found here.

A Brazilian console uses NTSC line timings and runs at 60Hz.  Brazilian consoles uses the PAL-M color system for composite video and RF output.  No Brazilian Master Systems will output RGB without modding, they do not offer anything better than composite video output.  Their power supplies  are also unique.  US TVs will have no issue showing a PAL-M composite image other than the issue that the image will be in black and white because the PAL color encoding system is sufficiently different from NTSC that US TVs will not be able to decode it.  Games released exclusively in Brazil are totally compatible with US consoles and most should have little trouble running in a PAL console.

Important Modern Accessories

HD RetroVision Genesis Component Video Cable + Model 1 Genesis A/V Adapter for Genesis 2 Cable (photos courtesy of Castlemania Games)

The HD RetroVision Genesis Component Video Cable works with any Sega system that provides RGB output.  This includes every Sega system with a DIN or mini-DIN connector from the Mark III to the Nomad and Genesis 3.  The cable has circuitry to convert the RGB video into Component video and will amplify weak RGB signals from devices like the Mark III.  It will not fix jailbars, those are inherent in the signal generation process and circuitry layout on the systems' PCBs. Fixing jailbars requires internal modification but they are generally not annoying except with games with wide swaths of single color areas.  Component video it will show a substantial improvement over composite video.  The HD RetroVision cable uses a 9-pin mini-DIN connector and the the Master Systems and Mark IIIs use an 8-pin DIN connector, so you will need the Genesis Model 1 adapter for these cables.  Do not use a Genesis 32x to Model 1 adapter, that will not transmit audio properly through to the HD RetroVision cable.

Wireless 2.4G and Bluetooth Controllers (photo courtesy of Amazon)

There are good options for wireless controllers available to the Genesis, and those options also work with the 8-bit systems as well as the wired 3-and 6-button Genesis controllers.  The Pause button on all the 8-bit Sega consoles triggers a hardware interrupt, so it cannot be added via a controller button.  On these controllers, buttons B & C replicate Buttons 1 & 2, respectively, on the 2-button Sega Control Pad.

The 8bitdo M.30 2.4g is a fine controller and fairly inexpensive at $24.99.  The Retro-bit Wireless 8-Button Arcade Pad is nearly identical but comes with a USB as well as a DE-9 adapter and retails for $34.99.  The Krikzz Joyzz has a SMS 2-button mode for compatibility with unpatched games which only work with a 2-button controller, whereas other controllers do not, but is more expensive at $39.00.  Retro-bit and 8bitdo also make Bluetooth versions of their controllers but sell the DE-9 adapters separately.  I prefer 2.4g controllers over Bluetooth controllers because 2.4g has less latency than Bluetooth as a general proposition.

Master EverDrive X7 (photo courtesy of Krikzz)

The only person who has ever made a flashcart specifically for the Sega 8-bit systems, to my knowledge, is Krikzz.  His first flashcart was the Master EverDrive, which worked by copying ROMs from an SD card to a flash memory chip and used an FRAM for non-volatile memory for the (8) Master System games which originally offered a battery backed saving feature.  This cartridge has been discontinued by Krikzz but has been widely copied and is available from Chinese sellers via eBay or Aliexpress.

Krikzz' current flashcart is the Master EverDrive X7.  This cartridge copies ROMs from an SD card to a RAM chip, which is faster than using a flash memory chip because you have to erase flash memory before programming it.  It also has a battery to keep the battery backed memory saves safe, even if you turn the console off.  The EverDrive will save the contents of the battery backed memory to SD card when you load another game.  It supports up to 4MiB ROMs and 32KiB SRAM, but no official cartridge ever used more than 1MiB ROM or 8KiB SRAM.

Finally the X7 has support for save states and in-game menu reset.  This save state functionality comes with several limitations however due to the limitations of these consoles.  First, as the controllers do not provide a start button on the controller, the button combo to enter the menu or save a state is much easier to trigger unintentionally.  The save state and in-game menu rely on signals only available on a non-Japanese Master System to detect button presses, so the Mark III, Japanese Master System and a Power Base Converter (of any region) will not work with save states and in-game menu.  The Mark III and Japanese Master System also require pin converters to use an EverDrive at all.  The Mega Sg supports save states and in-game menus.  

SMSFM Mod (photo courtesy of Tim Worthington)

All Master System games support PSG sound, but 42 Mark III/Japanese Master System games also officially supported FM sound.  This is an impressive ratio given that only 84 Mark III/Japanese Master System games were actually released.  FM sound was only officially supported on the Mark III with the FM Sound Unit add-on or with a Japanese Master System, which has the FM sound chip, the YM2413, built in.  In addition there were 18 games never released in Japan that support FM sound.  Only 8 of those 42 games were exclusively released in Japan, but 2 more games only have support in their Japanese versions (Phantasy Star, Y's: The Vanished Omens) and 1 only support FM sound with a Japanese region console (Wonder Boy III: The Dragon's Trap).  Ys and WB3 can be patched to have the FM sound available to the English version and PS can be patched with a English translation which also provides switchable FM sound.  Finally, 6 other games and 1 demo have support for FM sound which can be enabled via ROM patching.

Outside of software emulation and hardware FPGA simulation (Mega EverDrive X7 Mega EverDrive Pro, Mega SD, Mega Sg, MiSTer), there were two methods that have been devised to allow non-Japanese consoles to playback FM sound.  There was the PowerBase Mini FM developed by Rene from db Electronics, and as its name implies it is designed for a Genesis, but the product has been discontinued and did not provide a card slot for the 3-D glasses adapter.  Tim Worthington (etim) designed the SMSFM mod to address the issue that non-Japanese systems had no way to enjoy the FM audio that many SMS games support.  This mod is still available for sale and is likely the number one reason why you should buy a Master System today over just relying on a Genesis for your 8-bit Sega gaming. 

The SMSFM mod board plugs into the expansion port of a Master System but requires the connector to be soldered as well as a audio patch wire to be soldered to the Master System's mainboard.  It currently includes a good clone of the YM2413 chip called the UM3567.  The mod board used to come with the YM2413B chip, which used a surface mounted package and sounded a little more different to the YM2413 than the UM3567.


  1. Exellent article as usual. I'd like to point put some small errors: the game gear can run two player sms games with another gamepad connected to the link port and a (official?) cable adapter. Source:
    The start button on Gamegear is used as a "pause" button for sms games.
    It seems possibile (requires modding an patching) to use a sms light gun on a rgb out enabled game gear. Source

    1. I'm glad these were the kind of errors found, and not something major!

  2. Thanks for the great article!
    I've found anohter small mistake: no brazilian Master System has RGB.
    Although the 2 first versios had a 5 pin DIM plug, it's used for a dual voltage power supply. Source:
    That's weird but looks like it was the way Tectoy had to make it work with PAL-M system, that has a color subcarrier frequency that alternates the phase of the signal and uses slightly different frequency.

    1. Excellent information, much appreciated. Information about the Brazilian consoles is a bit obscure in English.