Amdahl board (left); the same board in storage box (right)
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.
The bottomside wiring (detail); close-up of heatsinks. The small chips inbetween are arrays of termination resistors.
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⇗
