Back in the day,
synthesizers weren't the all-in-one
integrated packages you see today. The equipment consisted of several
modules wired together, each with their own
function.
Programming these devices was done by connecting
patch cords between these modules.
Moog was the
father of the modular synthesizer design later
adopted by other companies such as
ARP.
Modules used in Moog Modular Systems:
901 VCO / LFO
901a VCO Driver
901b VCO
901c VCO Output
901d VCO Output
902 VCA
903 White Noise Generator
903a White / Pink Noise Generator
904 VCF
904a Low-Pass VCF (the famous patented one)
904b High-Pass VCF
904c Filter Coupler
905 Spring Reverb
907 Filter Bank
907a Fixed Filter Bank
909 Power Supply
911 Envelope Generator
911a Delayed Trigger
912 Envelope Follower
914 Extended Fixed Filter Bank
921 VCO
921a VCO Driver
921b VCO
923 Noise Generator / High- & Low-Pass VCF
928 Sample/Hold
930 Power Supply
950 49-Note Keyboard
950a ?
950b Scale Programmer
952 49-Note Duophonic Keyboard
952a Duophonic Keyboard
955 Ribbon Controller
956 Ribbon controller
958 Pedal Controller
959 Joystick Controller
960 Sequencer
961 Sequencer Interface
961CP Sequencer Interface Panel
962 Sequential Switch
984 4x4 Matrix Mixer
991 VCF / Attenuator
992 CV
993 Trigger / Envelope
994 Jack Multiples (2/4)
995 Attenuator
995a Reversible Attenuator
1120 Foot Pedal
1123 Sample/Hold
1130 Drum Controller
1131 Percussion Controller
1150 Ribbon Controller
1528 Sample/Hold
1584 Mixer
1617 36-band String Filter
1630 Frequency Shifter by Harald Bode
1634 Pitch-to-Voltage Converter
6401 Ring Modulator
CP1 CV/Trigger Outputs
CP2 CV/Trigger Outputs / Filters
CP3 4x1 Mixer
CP3a Mixer
CP4 CV/Trigger Outputs / Attenuator
CP4a CV/Trigger Outputs
CP5 CV/Trigger Outputs
CP6 CV/Trigger Outputs
CP7 CV/Trigger Outputs / Multiples
CP8 Power Switch
CP8a Power Switch
CP9 Power Switch
CP11 Mixer / Triggers / Outputs
CP35 Attenuator
DVCO-1 Dual VCO
SF-1 String Filter
I created this list by combining several more incomplete ones found on the web. I can't say this one is final and complete, though. /msg me if you know of more units that exist.