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[previous article] [next article]A new breed of Sun file server and workstation is starting to appear at the ECN, the Sun-4. This new machine, the fastest available from Sun, does not use the familiar 68XXX architecture of the earlier Sun-2 and Sun-3 series from Sun. It instead uses a new RISC-based architecture, designed by Sun, called SPARC.
RISC, in this case, stands for Reduced Instruction Set Computer. That is to say a computer which has fewer instructions when compared to a Complex Instruction Set Computer (CISC) such as a VAX or a 68XXX based machine. The notion of a reduced instruction set computer comes from some research done by IBM in the early 1970's. Researchers found that only a small number of a CISC processor's instructions were used in most of the programs run on that processor. Researchers both at IBM and the University of California at Berkeley built machines which incorporated these core instructions and accomplished those tasks done by the instructions they left out by means of sub-routines. By leaving out instructions the builders of these machines were able to increase the speed of the common instructions and add additional features to the processor such as large arrays of registers. This allowed RISC processors to run faster than their CISC counterparts using the same technology to build the processor.
The two current models of Sun-4 which you will see arriving at ECN are the 4/280 and the 4/110. The 4/280 is rated at about 10 MIPS and the 4/110 at about 7 MIPS. These speed figures are somewhat high and misleading. MIPS measures the number of instructions per second a processor can execute. On a RISC machine this is quite high. However, since RISC machines must accomplish some tasks by use of sub-routine calls, the speed of a given program will not be quite as fast as these MIPS numbers would indicate. Tests run by the ECN staff indicate a relative performance of about 7 times a VAX 11/780 for the Sun-4/280 running our standard suite of benchmark programs.
As with any different architecture, some problems may occur when bringing programs over to a Sun-4. According to Sun these problems will be few for several reasons, most notably the fact that they used the 68XXX architecture as a model for their processor. In any case, a document is available from Sun to any interested ECN users describing the differences between the Sun-4 and Sun-3 machines and what to look out for in moving programs between these machines. Contact your site specialist for a copy of ECN #92 Sun--Porting Software to SPARC System.
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