via this auction
"Vintage digisound 24 Module Synthesizer British company Digisound modules are affordable, innovative, well designed, and sound great. Digisound's own printed circuit boards are in this wooden box enclosures. Some are cream-coloured metal front plate individually cut and hand-labelled and some are white.
The Tolex covered case was built by the late Kevin Louis Lightner of the website synthfool.com. Most of the modules are built off the Curtis chip architecture from Curtis Electromusic Specialties. 
The solid state reverb unit (Module 80-17 Reverberation) works off a 3328-stage bucket brigade set of chips to produce a useful reverberation time of about 3 seconds. The VCF module labeled MOOG is built off the MOOG ladder filter.
The two 80-5 Processor modules are not multi patch panels but are quazy quad panners.
The VCDO is a fixed wave table with voltage control.
There are 11 manuals that explain some of the modules. In the manuals are schematic diagrams to help understand the components used in the build design and component part lists.
List of the manuals:
80-2 Voltage Controlled Oscillator Module
80-3 V.C. Low Frequency Oscillator Module
80-4 Voltage Controlled Mixer Module
80-5 Processor Module
80-7A V.C. State Variable (multimode) Filter Module
the 80-7A State-Variable Filter, featured optional 12 or 24dB operation for low-, high- or band-pass filtering, plus a notch (band-reject) filter. This is a very versatile module, its band-pass mode being my personal favorite.
80-9 Dual Voltage Controlled Amplifier Module
80-11A Dual Ring Modulator Module
80-13 External Input Module
80-16 Dual Resonant Filters Module
80-17 Reverberation Module
80-23 Quad Low Frequency Oscillator Module
List of modules stating from the top and going from right to left:
80-13 External Input Module
(3) 80-2 VCOs
80-21 Voltage Controlled Digital Oscillator
80-11A Dual Ring Modulator
80-5 Processor
80-7A State-Variable (multimode) Filter
Voltage Control Filter L
80-16 Dual Resonant Filters
80-9A Dual VCA
80-4A Voltage Controlled Mixer
2nd Row:
80-23 Quad LFO
Voltage Control Low Feq Oscillator
80-12 Noise Generator With Sample & Hold
(2) 80-18 Multi-function Envelope Generator
80-17 Reverberation Unit
80-5 Processor
80-7A State-Variable (multimode) Filter
Voltage Control Filter L
Moog VCF
80-9A Dual VCA
80-14 Stereo Power Amplifier"
