Modular synths typically come with filters; analog computers typically don't. Analog computers do come with integrators which could be considered very weird lowpass filters. Likewise a differentiator can be considered a weird and always imperfect highpass filter.
Both typically come with adders, but a modular synth will call this a mixer. Both typically come with multipliers but a modular synth will often call a multiplier a ring modulator (and it might not multiply all four quadrants).
(Just to make things more confusing, at RF frequencies the word "mixer" typically refers to a multiplier rather than an adder. In the audio range, mixers are adders.)
Modular synths are designed for making sound; analog computers are designed for precise, much slower waveform generation. Its circuits might not even be capable of operating fast enough to make sound.
- Bitwig
- Softube Modular
- Cherry Audio Voltage Modular
- VCV Rack
- miRack
- Reaktor Blocks
- Nord Modular
- Max/MSP BEAP
Can't emphasize enough how awesome Eurorack is though