What is this rare multi-user UNIX workstation? (Plexus P/20)

What we have on the bench is a Plexus P/20 dual processor multi-user UNIX computer from 1985. This was likely designed for office user and support 8 concurrent users in this configuration, with up to 16 possible with the use of an extra I/O processor card. This machine doesn’t seem to be documented anywhere other than a simple brochure (link below) so let’s see if we can unravel some of the mysteries of this machine. Part 1: This part Part 2: Coming soon! -- Links My Github Repo (with ROM dumps and images) Plexus P/20 Brochure: Plexus Unix: MFM emulator: Fujitsu Hard Drive Brochure: Omti 5200 Manual: Adrian’s Digital Basement Merch store: Adrian’s Digital Basement ][ (Second Channel) Support the channel on Patreon: My GitHub repository: -- Tools Deoxit D5: O-Ring Pick Set: (I use these to lift chips off boards) Elenco Electronics LP-560 Logic Probe: Hakko FR301 Desoldering Iron: Rigol DS1054Z Four Channel Oscilloscope: Head Worn Magnifying Goggles / Dual Lens Flip-In Head Magnifier: TL866II Plus Chip Tester and EPROM programmer: (The MiniPro) TS100 Soldering Iron: EEVBlog 121GW Multimeter: DSLogic Basic Logic Analyzer: Magnetic Screw Holder: Universal ZIP sockets: (clones, used on my ZIF-64 test machine) RetroTink 2X Upconverter: (to hook up something like a C64 to HDMI) Plato (Clone) Side Cutters: (order five) Heat Sinks: Little squeezy bottles: (available elsewhere too) --- Instructional videos My video on damage-free chip removal: --- Music Intro music and other tracks by: Nathan Divino @itsnathandivino