The SID is a synthetizer chip built to give a “voice” to the classic home computer Commodore 64.
The sounds and music capabilities of the Commodore 64 were really ahead at that time, and everyone of us remember the tunes of tons of games played on the C64.

The sound  capabilities of the C64 were really appreciated by the demoscene movement during the 80s and early 90s, and even experimental electronic musician incorporated that sound in their compositions.

In the 90s a little synth manufacture started their businness building the first SID based synth, the SidStation.
The sidstation uses a single chip as voice generator.
When it first came out there was little interest in the machine, it was priced and sounded like a C64…
When people started hearing the sidstation sounds in pop or dance tracks understood the power of this little chip…

Today the Sidstation is a priced collectable piece of gear as they were made on a limited number (under 1000 units) and are out of production from years.
So the alternatives to get a midi controllable SID are a few…

• MIDIBOX SID (a Sidstation-like diy synth)
• HARDSID (a “sid engine” controllable thru usb)
• MIDIBOX WILBA (an evolution over the classic Midibox)
• MSSIAH (a midi controllable program on cartridge for the C64)