Prime Computer Inc picked the wrong target yesterday when it announced that its new MIPS RISC-based workstation outperformed the Iris from Silicon Graphics Inc (see front) because at about the same time, the Mountain View, California company was announcing a new Iris-4D – based on the same MIPS RISC processor. The Iris-4D are rated by Silicon Graphics at seven times the performance of the VAX-11/780 in MIPS using the Dhrystone benchmark – five times more powerful running actual user applications, delivering a sustained five MIPS of integer computing performance. The first member of the line is the Iris 4D/60, a 12-slot superworkstation with RISC processor subsystem from MIPS Computer Systems, Sunnyvale, including 8MHz 32-bit RISC CPU offering up to three times the computing performance of Silicon Graphics’ previous Iris 3100 Series. Graphics performance has been enhanced by incorporating 38 custom and semicustom graphics chips in the design. It performs 140,000 32-bit three dimensional floating point transformations per second and renders over 4,500 100-pixel polygons per second with smooth shading and hidden surface removal. It offers 24 colour bit-planes for more than 16m col-ours; four user-accessible system planes for overlay or underlay, menu and windowing functions; a 24-bit Z-buffer enabling hidden surface removal with greater accuracy and realism; high-level primitives such as splines and surfaces for more accurate renderings; and a multi-mode graphics windowing environment. Standard configuration includes 4Mb CPU, eight colour bit-planes for 256 colours); four system planes, a Weitek-based floating point accelerator board; a 170Mb ESDI disk and controller; a 19 1,280 by 1,024 60Hz non-interlaced colour monitor; keyboard and mouse; and a floor-standing chassis with 12 VME slots and a 1,000-watt power supply. Software compatible with the previous generation, it runs Unix System V.3 with a base price of $74,000. Ships April.