To allow CERN to test and maintain HIPPI equipment (High Performance Parallel Interface), a powerful test falcility is required. A tester has been developed at Los Alamos National Laboratories [9,10]. The CERN HIPPI testbox allows testing of HIPPI equipment both inside and outside the specifications. This includes the possibility of deliberately introducing errors. The main features of this testbox are: Manual set-up Processor controlled set-up Possibilities for remote analysis Checking the HIPPI specifications Checking illegal conditions

This card, based on a "4 slot DEC module", arbitrated the access priority of 15 datalinks of a CERNET node. Each datalinks could transfer data full duplex at 2.5 Mbit/sec over 1 Km of twisted pair (POD) cable. This was the frontier technology in 1980. The modest amount of integrated circuits was compensated by printing on the board photographs of the hardware designers, whose Belgian, Dutch and French nationality was underlined by the the short poem.

A diode matrix is an extremely low-density form of read-only memory. It's one of the earliest forms of ROMs (dating back to the 1950s). Each bit in the ROM is represented by the presence or absence of one diode. The ROM is easily user-writable using a soldering iron and pair of wire cutters.This diode matrix board is a floppy disk boot ROM for a PDP-11, and consists of 32 16-bit words. When you access an address on the ROM, the circuit returns the represented data from that address.

Each module contained 8 circuit cards for a total of about 300-500 uncovered transistors packaged with face plates so the Freon plates wouldn't touch the circuits. (cooling plates that surrounded each module).