This circuit board, part nr 56-135958-124, was used in the Amdahl 580 series of mainframe computers¹, around 1982.
The multi-layer board carries 121 Fujitsu bipolar ECL chips, 16 of them (the larger ones, marked MB7703H) are 4K-bit RAM with 4 ns access time. The remaining chips are LSI gate arrays. Each chip has its own radiator (heatsink) for forced air cooling; the board was mounted horizontally in the system rack. Size of the board is about 28 x 32 cm.
We don't know the functionality within the system of this particular board. It is largely determined by the quite complex discrete wiring² on the board's bottomside. This wiring has probably been applied by a wire-bonding robot.The grid spacing is about 1 mm, the isolated wires are a few tenth of a millimeter thick. The wiring is protected by a transparent acrylic plastic sheet.
The Amdahl board was donated by Dirk Hannema from Uithoorn, The Netherlands.
¹) Datapro Research: Amdahl 580 Systems, 1982⇗
²) Amdahl Company: Amdahl 50 Large Scale Integrated Circuit Manual, 1981⇗