The SPARCstation 1 (Sun 4/60, code-named Campus) is the first of the SPARCstation series of SPARC-based computer workstations sold by Sun Microsystems. The design originated in 1987 by a Sun spin-off company, Unisun, which was soon re-acquired. The SPARCstation 1 has a distinctive slim enclosure (a square 3-inch-high "pizza box") and was first sold in April 1989, with Sun's support ending in 1995. Based on a LSI Logic RISC CPU running at 20 MHz, with a Weitek 3170 (or 3172) FPU coprocessor, it was the fourth Sun computer (after the 4/260, 4/110 and 4/280) to use the SPARC architecture and the first of the sun4c architecture. The motherboard offered three SBus slots and had built-in AUI Ethernet, 8 kHz audio, and a 5 MB/s SCSI-1 bus. The basic display ran at 1152×900 in 256 colours, and monitors shipped with the computer were 16 to 19 inch greyscale or colour. Designed for ease of production to compete with high-end PCs or Macs (its principal competitors were the IBM PS/2 Model 80, the NeXT Computer, and Sun's own 3/80), it sold for between about US$9,000 (with no hard disks), to US$20,000 — and in the first year around 35,000 units were sold. Design The SPARCstation 1 features several distinctive design and packaging elements driven internally by system designer Andy Bechtolsheim and externally by design house frog design. Bechtolsheim specified that the motherboard would be the size of a sheet of paper and the SBus expansion cards would be the size of index cards, resulting in an extremely compact footprint. The external design motif includes dot-patterned cooling vents on the side which are echoed by a "dimple" pattern on the front face, and "Sun purple" feet. Memory The SPARCstation 1 takes 30-pin SIMMs in groups of four. It can take either 1 MB or 4 MB SIMMs as long as the size is consistent within a bank. There are a total of four memory banks, which can give a total of 64 MB of memory. Memory bank 0 (composed of U0311, U0322, U0309, and U0307) should be filled first. If not, the OpenBoot firmware will hang while memory checking. Disk drives The SPARCstation 1 has space for up to two hard drives and one floppy drive internally. The machine will take any 50-pin SCSI-2 hard drive, but the OpenBoot firmware will not boot from any partition which starts or ends after 1024 MB.