As expected, MIPS Technologies Inc has now received first silicon on the high-performance floating point-intensive R4000 iteration of its R-series RISC with 4m transistors, the one known as TFP. Toshiba Corp is making TFP for MIPS’s parent, Silicon Graphics Inc, which has already announced a high-end TFP-based Power Challenge parallel system which is due by year-end. TFP’s 300 MFLOPS peak performance and 1.2Gb per second bandwidth to the external cache has apparently already attracted the attention of several supercomputer manufacturers. The two-chip set – which has two integer units, two floating point units, two load-store pipes and one branch unit – won’t replace MIPS’s R4400 but will satisfy Silicon Graphics’s need for floating-point performance until the T5 or Terminator arrives around the end of next year. Microprocessor Report expects the 75MHz TFP to match the integer performance of the 150MHz R4400 and double its floating point mark; that implies 100 SPECint92 and over 200 SPECfp92. Digital Equipment Corp’s current 200MHz Alpha AXP 21064 is rated at 200.4 SPECfp92. TFP can issue four instructions per cycle, the highest of any conventional RISC CPU. Although that’s the same as IBM Corp’s Rios RISC, Rios can only issue four instructions at a time if they consist of an integer operation, floating-point, condition-code and a branch, which doesn’t happen very often and therefore the chip rarely performs at peak issue rate, Microprocessor Report observes. Due to its complexity however, the TFP may not ship until mid-1994. TFP is the first to implement the MIPS IV architecture, which includes all of the 64-bit extensions in the 4000’s MIPS III. New extensions are for floating-point performance and some instructions are similar to those in Sparc version 9 and Alpha. No pricing or availability details yet, but MIPS hopes it will be between $2,000 to $3,000. Microprocessor Report estimates manufacturing cost of the integer and floating-point units at $850, compared with $480 for the Intel Corp Pentium and $185 for R4400.
