S is for... SID chip
The most famous retro sound chip, the SID found in Commodore home computers such as the C64 was unquestionably the most powerful chip of its time, featuring three oscillators, filtering, ring modulation, selectable waveforms, and more.
If you want to get that distinctive SID sound in your modern DAW, you have a number of options. HardSID and SidStation are hardware solutions that use real SID chips, for a totally authentic sound; for convenience, check out virtual instruments like QuadraSID, plogue chipsounds and Nexus2 (with the SID expansion). Alternatively, grab a MSSIAH cartridge and a real C64, and plumb it into your rig like a MIDI synth!
S is also for… Sound chips
There are plenty of famous chips beside the SID, such as the Atari POKEY (Atari 2600), Ricoh 2A03 (NES), Konami SCC (MSX), and YM2612 (Megadrive/Genesis).