The SEGA CDX was released in 1994 and is the cream of the crop when it comes to SEGA systems in my book. This thing is a beauty to behold. When you hold it in you hands, you can tell you’re holding a nice piece of hardware. It is heavy and feels well constructed, and if you ever open it up (which you should NEVER do) you will see that the same quality appears on the inside as far as construction is concerned. It is bristling with ports and buttons on all sides. It plays SEGA Genesis, SEGA CD games and music CD & CDGs. It’s basically a portable SEGA CD / Music player, but I would love to see someone jogging down the street with this thing strapped to their hip!

I never had one back in the day. I do remember however seeing the box in Toy R Us, which I believe was the only chain allowed to sell the unit. It was released at the end of the SEGA CD era, and was discontinued along with the SEGA 32X as the SEGA Saturn was on its way.


Model MK-4121

I have had may units and they are all the same. I don’t believe there were any major modifications ever made to the unit. As it was only around for about a year and is basically itself a revision of the SEGA CD. But instead of putting it on the CD page, I thought it deserved its own page.

As mentioned above this thing is a beauty. Starting on the front of the machine you have two standard SEGA Genesis controller ports. Between the controller ports is power button. If you need help hooking this baby up visit our HOW TO section.

On the top front of the machine from right to left you have:

Open button – to open the CD tray, which you close manually.

Back button – to restart the song currently playing, pressing again will cycle backwards through the CD tracks. (not used for gaming)

Fast Forward button – to skip to the next song on a music CD (not used for gaming)

Right in the middle you have the LCD Display. This will show you information about the music CD (track number)

Play / Pause button – again used for controlling the music CD functions, not games.

Stop button – that’s right… it stop the music from playing.

Reset button – This functions like the reset button on the SEGA Genesis. It will restart a game as if it were reinserted.

On the left side of the SEGA CDX you have a headphone jack, a volume control for the headphone jack and then and audio out to run the sound to your home stereo system. Also on this side is the tab to open the battery compartment.

Note: The system can operate using two AA-Bateries, but will only play music CDs this way. You can not play cartridge or CD games using the batteries, the system must be plugged in to do so.

On the back of the SEGA CDX we have the AC Power Port. This is used with the SEGA MK-4122 Power Supply. The specs on this power supply are unique and as such:


And finally, on the right side of the SEGA CDX we have the AV OUT port. This uses the same SEGA RCA Cable that the SEGA Genesis 2 and SEGA 32X use.


  • Unit Lifetime: 1993-1995 (US)
  • Resolution: 320 x 224
  • Colors Available: 512
  • Colors on Screen: 64
  • Power Requirements: 9.5V 1500amps
  • Sound: Added 10-channels to the Genesis specs
  • Games Released US: 147 CD + 811 Genesis

The SEGA CDX came with 3 CDs:

• Ecco the Dolphin CD edition

• SEGA Classics CD (4-in-1)

  1. Columns
  2. Golden Axe
  3. The Revenge of Shinobi
  4. Streets of Rage


Because of its rarity this is an expensive system to collect. But honestly it was $400 when it was released and you can find them for about that price now! So it merely held its value! If you do try and acquire one, make sure it has the original power supply. The Genesis 2 power supply (MK-2103) will fit and turn on the system, but causes problems when trying to run the CD. DO NOT DO IT!

The 6-Button Controller

The SEGA CDX came packed with the SEGA 6-Button Controller.

In 1993 SEGA made a 6-button controller for the SEGA Genesis. This was partly due to fighting games like Street Fighter that required the extra inputs. To me this is a perfect analog controller. It’s slightly smaller and easier to handle than the 3-button controller while adding 3 more action buttons.

The new buttons are labeled X, Y & Z and smaller than the original A, B & C buttons. The are also rounded or convex while the original buttons retain the recess concave shape. This makes the very easy to navigate. The buttons are sturdy and responsive.

The d-pad is slightly smaller than the original 3-button controller and raised a little higher. It had a little more movement that feels nice.

Just like the 3-button they are sturdy and well made, but time waits for nothing and maintenance or repair may be necessary.

NOTE: There is a button located on the right shoulder. This is a MODE button for a few games (ones made before the controller was) that did not work with the 6-button controller was used. Holding this button down and then turning on the system and waiting for the game to load will make the controller function like an original 3-button controller.

SEGA Genesis Controllers

The 3-Button Controller

Even though the SEGA CDX included the 6-button controller, the 3 button controllers will work fine on it.

The SEGA Genesis originally came with a 3-button controller. It has an 8-way directional d-pad, a Start button, and three buttons labeled A, B & C.

These controllers are fairly durable, but with original controllers being decades old now you find many that do not work. But when they are in good shape they are good quality controllers. They can be maintained, cleaned and repaired and I will go over some of that in the Gametrog Maintenance Section.

They feel beefy with a little weight and thick plastic and may feel a little big in smaller hands. The d-pad and buttons are responsive and it’s an all around solid controller. I have seen various cord lengths from plenty to short. There are also a few different internal changes over the years, but appeared the same cosmetically.

More SEGA Genesis Accessories

SEGA Genesis 6-Button Arcade Stick

The cream of the crop when it comes to Arcade style sticks for your Genesis.

SEGA Genesis 3-Button Arcade Stick

We take a quick look at the Arcade Power Stick for the SEGA Genesis.

QuickShot Eagle Flight Stick Controller – SEGA Genesis

Like flight-sims and shooters like Desert Strike? Then you might want to grab you a flight stick!

SEGA Genesis Activator

Trog steps into the octagon with the terrible SEGA Activator nerd-ring of shame.

SEGA CDX (Genesis) Games


The SEGA Genesis was the first 16-bit system to hit the US. This brought an expanded color palette and higher resolution and detailed graphics than the 8-bit systems before. Games started to resemble their arcade counterparts more closely and this was used as a selling point. You can find pretty much any game type you fancy for the system from arcade classics, RPGs, platformers and action titles. Sports games really started to grow with the 16-bit era with SEGA Sports and EA Sports leading the way. With the abundance of quality titles it is an easy system to collect for.


The SEGA Genesis is a cartridge based system. For most of the Genesis’ life the games came in a plastic box, with clips inside that held the cartridge. There are normally also tabs on the inside front that held the manual in place. These are the same boxes that were used for the SEGA Master System.

Being a plastic box these guys have held up pretty well. There is a clear mylar sleeve around the box that the game cover slips into. This allows the box art to hold up pretty well over time also. You can remove the game cover from the top or bottom of the box (opening the box gives a little slack to the mylar sleeve allowing you to reach in and pull out the cover. If yours is damaged you can even print your own cover and slide it in!

Most of the manuals were in color and informative (not like the lack of manuals with games these days). In addition to the manual you would often find several postcard like inserts that might offer phone numbers for tips or other games.

In the later years of the SEGA Genesis many games were shipping in a cardboard box. This box had close to the same dimensions of the plastic boxes, but lost the durability. There is a box with and indentation created to hold the cartridge and the manual was usually found behind the game itself. So you can pop out the game, but you would have to open the box from the top to pull out the manual. It’s also a pain to put the manual back in sometimes as the flaps that create the hole for the cartridge will snag on the manual. Also by this time most of the manuals were printed in black & white. Over the cardboard box container is a cardboard sleeve that slides over everything from the top or bottom. As the whole package is now cardboard these guys do not hold up over time as well as the plastic one.

If you have the option, get the plastic box whenever you can!


The SEGA CD added several new features to the standard cartridge based games for the Genesis. First and foremost was the storage capacity of the CDs themselves. They allowed much more content to be added than any cartridge could hold. The CD technology also allowed for CD quality music which was a major improvement. Many SEGA Genesis title were re-released in CD format to take advantage of these new features by adding animated cut-scenes, voice acting and extra levels.

One of the biggest new features was hardware sprite scaling. This feature was similar to the sprite scaling of the Super Nintendo but more robust. Basically a large detailed graphic image like a vehicle or spaceship could be drawn once but smoothly scaled down or up in size. Games like Batman Returns and Soulstar among others made great use of this.

One of the issues that the SEGA CD didn’t address was the color palette. The SEGA Genesis could display 64 colors on screen at a time and though it was considered increasing it during the development of the CD in the end it retained the same color abilities. This worked fine the Genesis, but when you started adding video to games or making complete Full-Motion games it made the image very grainy. They would address this with the release of the SEGA 32X later, but it was too late.

The case for the SEGA CD is a big one. They are taller than SEGA Genesis boxes and a little wider. They are built from plastic and have a hinge on the top and bottom of the case that allows it to open like a book. The manual is also the cover of the game. Once opened you could remove the manual from the front of the case where it was held in with some small tabs. This can bit a bit of a pain with thick manuals and you can often see the damage to the manual on the top and bottom where the tabs hold it in place.

The back of the case had an insert with the standard game information and pics. This sheet could be removed by popping the black plastic along the left edge of the case out (easy to do and easy to put back in).

The back part of the case holds the CD with a standard CD clip right in the middle. There was also a foam rectangle that was placed over the CD to fill up the vast amount of empty space inside the case and help keep the CD in place should it come loose from its clips.

These cases are a bit fragile. The hinges on the top and bottom that hold the cover flap often break. The front and back of the case can also have cracks. But with the cover and back insert able to easily be removed, you can switch everything out to a case in better shape if you want to.

Despite their shortcomings these guys do look good on a shelf together. The cover design and graphics were often awesome.

The first few releases for the SEGA CD actually came in cardboard cases. These were about the same dimensions as the plastic one in height and width, but were about half the thickness. You would open the top flap when you could access and pull out a standard  music CD style case with the game inside and the manual was tucked behind it.

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