The machine was built in a plus-sign-shaped cabinet with a pump and heat exchanger in the outermost 18 in (46 cm) of each of the four arms.
Cooling was done with Freon circulating within the machine and exchanging heat to an external chilled water supply.
Each arm could hold four chassis, each about 8 in (20 cm) thick, hinged near the center, and opening a bit like a book.
The intersection of the "plus" was filled with cables that interconnected the chassis.
The chassis were numbered from 1 (containing all 10 PPUs and their memories, as well as the 12 rather minimal I/O channels) to 16.
The main memory for the CPU was spread over many of the chassis.
In a system with only 64K words of main memory, one of the arms of the "plus" was omitted.

The logic of the machine was packaged into modules about 2.5 in (64 mm) square and about 1 in (2.5 cm) thick.
Each module had a connector (30 pins, two vertical rows of 15) on one edge, and six test points on the opposite edge.
The module was placed between two aluminum cold plates to remove heat.
The module consisted of two parallel printed circuit boards, with components mounted either on one of the boards or between the two boards.
This provided a very dense package; generally impossible to repair, but with good heat transfer characteristics.
It was known as cordwood construction.
The machine was built in a plus-sign-shaped cabinet with a pump and heat exchanger in the outermost 18 in (46 cm) of each of the four arms. Cooling was done with Freon circulating within the machine and exchanging heat to an external chilled water supply. Each arm could hold four chassis, each about 8 in (20 cm) thick, hinged near the center, and opening a bit like a book. The intersection of the "plus" was filled with cables that interconnected the chassis. The chassis were numbered from 1 (containing all 10 PPUs and their memories, as well as the 12 rather minimal I/O channels) to 16. The main memory for the CPU was spread over many of the chassis. In a system with only 64K words of main memory, one of the arms of the "plus" was omitted.
The logic of the machine was packaged into modules about 2.5 in (64 mm) square and about 1 in (2.5 cm) thick. Each module had a connector (30 pins, two vertical rows of 15) on one edge, and six test points on the opposite edge. The module was placed between two aluminum cold plates to remove heat. The module consisted of two parallel printed circuit boards, with components mounted either on one of the boards or between the two boards. This provided a very dense package; generally impossible to repair, but with good heat transfer characteristics. It was known as cordwood construction.
CDC 6600