Computer history: graphical systems (1974 – 1978)

The PDP 11/60 and the Evans & Sutherland PS/2

The CDC Digigraphic graphical computer system was replaced mid of 1979 by a DEC PDP 11/60 and an Evans & Sutherland Picture System/2 (PS/2). The PS/2-system was bought for US$ 110.000, the PDP 11/60 system cost was roughly the same. The PDP 11/60 system comprised 192 KB memory, a CPU with hardware floating point unit and four RL01-disk units (removable packs) with a capacity of 5 MByte each.

The planned installation was delayed from early April until end of July because the transport of the PDP and the E&S equipment during its flight to The Netherlands was not handled well. The system frame of the PDP was displaced ten degrees to the left and the back, a – amazingly still operating – monitor tube was displaced five centimetres to the back. One could touch the boards through the front … At the end of July , a replacement PDP 11/60 system was installed and the other damages were repaired.

The PDP 11/60 with the four RL01-disk units and the Kennedy magnetic tape recorder
The PDP 11/60 with the four RL01-disk units and the Kennedy magnetic tape recorder

During the acquisition of the system, the Laboratory still tried to obtain an exemption of import taxes as the PS/2 graphical system was a piece of equipment for “scientific research” to be used only for “scientific research activiteiten”. This request was denied by the Committee for Tax-exemptions. In 1980, the time had arrived that mini-computers and graphical processing systems had become ordinary pieces of equipment.

End of 1980, the Picture System/2 was expanded to a Multi-Picture System. The main driver for that was the research group Telecommunication, which used this system for the simulation of the raster communication plan for the Netherlands First Army Corps (1LK).

The CDC Cyber 18-17: plotting and the Micro Development System

The CDC Cyber 18-17 (in short System 17), that was used earlier to drive the Digigraphic graphical display, was re-used as mini-computer to drive both the Calcomp 936-plotter and the Micro Development System (MDS). As an extension to the “Janus” program (the CDC CYBER PP-programma 1IR that drove the card reader, printers and the Calcomp plotter), an overlay was developed that made an hand-shake via a 6000-channel coupling with a program on the Cyber 18-17. The plot data was transfered to the Cyber 18-17, which in turn drove the plotter. The channel speed was 3-4 Mbyte/s. After plotting, the plot files remained a while on the system in order to replot them in case of dried-out plotter pen or any other malfunctioning. In the same way, data was transferred to and from the MDS.