Synthcart is a cartridge I developed for the
Atari 2600 game console
that turns it into a basic synthesizer with an argeggiator and built-in rhythm patterns.
The controls are designed so that it is possible to use without a TV, allowing it to function as a stand-alone synthesizer. Synthcart
requires a pair of Atari keyboard controllers or video touch pad controllers, which can be found on eBay.
● Play an assortment of familiar Atari sounds
● Use two different sound types at a time, one assigned to each controller
● 8th, 16th, and 32nd note arpeggiator
● Beat Box with many pre-programmed beats and fills
● Play two beats simultaneously to create custom beats
● Two tremelo settings
● Four attack/release settings
● User interface designed so that a TV is not required
● Easter egg: light show mode that displays color patterns based on
sound output. To activate, put the scale on "major" and put the left keypad on "pitfall" or
"saw" and play the notes: 4 7 8 9 8 9.
Which controllers work with it and where do I get them?
Keyboard Controllers, Video Touch Pads (Star Raiders controller), and the
Atari Kid's Controllers
I usually use the Video
Touch Pads which you can get on Ebay. The
Kids Controller is also good and
looks great, but is usually a bit more expensive (about $20-$30 for a pair.)
An Atari 2600 w/ power supply, TWO keyboard controllers, and a TV (or a VCR that includes a TV tuner and audio out).
Which Ataris will it work with?
It will work with all Atari 2600's including the Junior model (black and
silver). It also works on the Atari 7800. However, the 7800 doesn't have a
switch. So the 7800 will not be able to access all the sounds unless the B&W
switch mod is done (install a switch/toggle in place of the 7800's momentary Pause button).
There are PAL and NTSC versions, but not a SECAM version.
Is there a sequencer or drum beat editor on the Synthcart?
The beats cannot be easily edited. There are 33 beats and they are hard coded in the cartridge. There's not
enough memory to have any proper sequencing. The Atari only has 128 BYTES of RAM which is already filled.
However, since I've released the source code (see above), if you like to hack,
you can modify the beats and re-assemble the ROM into a version with your own beats.
Then you can run that on an emulator, krokodile cart,
or cuttle cart 1 or 2, or get Atariage
to make a custom Synthcart.
What generates the sound?
The sound is generated by the Atari 2600's built in sound chip (the TIA). The
cartridge doesn't have any special sound
generating hardware, and it is just a regular Atari 2600 cartridge.
How do I get a direct audio out?
You can do the modifications yourself: you just solder two wires to the Atari board and then connect them to
a RCA or a 1/4" connector.
Check out Ben's how-to page
to figure out where to solder the wires.
On Ben's page go to "How do get composite video from [whichever Atari you're using]?"
and it'll show you where to solder the audio wire (just do the audio mod, ignore the video portion).
Solder the other wire to any ground point.
this mod to get audio-out with a stereo option (one output per oscillator).
also the new A/V mod kits from 8bitdomain which are quite a bit cheaper than
the Cybertech mods that I use (which are no longer in production). I haven't tried these A/V kits
yet, but I've heard good things about them.
Other easier options are to get a VCR and use its tuner and A/V outputs or
get a video demodulator.
Do I have to have a modified Atari to use it?
No, you can just use your TV. Or you can hook it up to a VCR with
A/V out to get the audio.
Is there a way to sync the Synthcart to my gear?
Not automatically, but if you set your gear to the same tempo as the Synthcart
them at the same time, they will stay in sync since the 2600 clock is very
Some limitations that musicians should be aware of:
- The pitch on the Atari is very limited. I’ve set up a sound table of 12
notes from a major scale for each sound type.
While these notes are reasonably in tune with each other,
some sound types do not use a standard tuning.
For example, the bass sound is in C# major at -35
You will have to tune
your other sound modules accordingly or use a pitch shifter to
I have not found
this to be much of a problem.
- The tempo is only
adjustable in large increments.
The Atari demands a lot of the processor’s time to draw the
To have a fine tempo
adjustment would require me to update the tempo counter, arpeggiator, beat
box, and voice manager many times while drawing the screen, which is just not
Tempo values in BPM on the NTSC version are:
224.71 179.77 149.81 128.41 112.36 99.87 89.88 81.72 74.90 69.14. The values are calculated from
the Atari's clock frequency, so they are very accurate.
- Although Synthcart works with NTSC and PAL Ataris, it does not fully work on European SECAM Ataris since the B&W/Color
switch doesn't work the same way on those models. Half of the sounds will be inaccessible on SECAM models.