UltraSPARC
Encyclopedia
The UltraSPARC is a microprocessor
developed by Sun Microsystems
who is now a part of Oracle Corporation
and fabricated by Texas Instruments
that implements the SPARC V9
instruction set architecture (ISA). It was introduced in mid-1995. It was the first microprocessor from Sun Microsystems to implement the SPARC V9 ISA. Marc Tremblay
was a co-microarchitect.
microprocessor that executes instructions in in-order. It has a nine-stage integer pipeline
.
The integer register file
has 32 64-bit entries. As the SPARC ISA uses register window
s, of which the UltraSPARC has eight, the actual number of registers is 144. The register file has seven read and three write ports. The integer register file provides registers to two arithmetic logic unit
s and the load/store unit. The two ALUs can both execute arithmetic, logic and shift instructions but only one can execute multiply and divide instructions.
The floating-point unit consists of five functional units. One executes floating point adds and subtracts, one multiplies, one divides and square-roots. Two units are for executing SIMD instructions defined by the Visual Instruction Set
(VIS). The floating-point register file contains thirty-two 64-bit registers. It has five read ports and three write ports.
The UltraSPARC required a mandatory external secondary cache. The cache is unified, has a capacity of 512 KB to 4 MB and is direct-mapped. It can return data in a single cycle. The external cache is implemented with synchronous SRAMs clocked at the same frequency as the microprocessor, as ratios were not supported. It is accessed via the data bus.
process as Texas Instruments claimed it did not scale well to 0.5 µm processes and offered little performance improvement. The process was perfected on TI's MVP digital signal processor
(DSP) with some features missing such as three levels of metal instead of four and a 0.55 feature size, before it was used to fabricate the UltraSPARC to avoid a repeat of the fabrication problems encountered with SuperSPARC
.
Microprocessor
A microprocessor incorporates the functions of a computer's central processing unit on a single integrated circuit, or at most a few integrated circuits. It is a multipurpose, programmable device that accepts digital data as input, processes it according to instructions stored in its memory, and...
developed by Sun Microsystems
Sun Microsystems
Sun Microsystems, Inc. was a company that sold :computers, computer components, :computer software, and :information technology services. Sun was founded on February 24, 1982...
who is now a part of Oracle Corporation
Oracle Corporation
Oracle Corporation is an American multinational computer technology corporation that specializes in developing and marketing hardware systems and enterprise software products – particularly database management systems...
and fabricated by Texas Instruments
Texas Instruments
Texas Instruments Inc. , widely known as TI, is an American company based in Dallas, Texas, United States, which develops and commercializes semiconductor and computer technology...
that implements the SPARC V9
SPARC
SPARC is a RISC instruction set architecture developed by Sun Microsystems and introduced in mid-1987....
instruction set architecture (ISA). It was introduced in mid-1995. It was the first microprocessor from Sun Microsystems to implement the SPARC V9 ISA. Marc Tremblay
Marc Tremblay
Marc Tremblay is a distinguished engineer at Microsoft. Prior to joining Microsoft in April 2009, he was senior vice president and chief technology officer of the microelectronics business unit at Sun Microsystems. He was instrumental in the design of various microprocessors at Sun, including the...
was a co-microarchitect.
Microarchitecture
The UltraSPARC is a four-issue superscalarSuperscalar
A superscalar CPU architecture implements a form of parallelism called instruction level parallelism within a single processor. It therefore allows faster CPU throughput than would otherwise be possible at a given clock rate...
microprocessor that executes instructions in in-order. It has a nine-stage integer pipeline
Instruction pipeline
An instruction pipeline is a technique used in the design of computers and other digital electronic devices to increase their instruction throughput ....
.
Functional units
The execution units were simplified relative to the SuperSPARC to achieve higher clock frequencies - an example of a simplification is that the ALUs were not cascaded, unlike the SuperSPARC, to avoid restricting clock frequency.The integer register file
Register file
A register file is an array of processor registers in a central processing unit . Modern integrated circuit-based register files are usually implemented by way of fast static RAMs with multiple ports...
has 32 64-bit entries. As the SPARC ISA uses register window
Register window
In computer engineering, the use of register windows is a technique to improve the performance of a particularly common operation, the procedure call...
s, of which the UltraSPARC has eight, the actual number of registers is 144. The register file has seven read and three write ports. The integer register file provides registers to two arithmetic logic unit
Arithmetic logic unit
In computing, an arithmetic logic unit is a digital circuit that performs arithmetic and logical operations.The ALU is a fundamental building block of the central processing unit of a computer, and even the simplest microprocessors contain one for purposes such as maintaining timers...
s and the load/store unit. The two ALUs can both execute arithmetic, logic and shift instructions but only one can execute multiply and divide instructions.
The floating-point unit consists of five functional units. One executes floating point adds and subtracts, one multiplies, one divides and square-roots. Two units are for executing SIMD instructions defined by the Visual Instruction Set
Visual Instruction Set
Visual Instruction Set, or VIS, is a SIMD instruction set for SPARC V9 microprocessors developed by Sun Microsystems. There are three versions of VIS: VIS 1, VIS 2 and VIS 2+...
(VIS). The floating-point register file contains thirty-two 64-bit registers. It has five read ports and three write ports.
Cache
The UltraSPARC has two levels of cache, primary and secondary. There are two primary caches, one for instructions and one for data. Both have a capacity of 16 KB.The UltraSPARC required a mandatory external secondary cache. The cache is unified, has a capacity of 512 KB to 4 MB and is direct-mapped. It can return data in a single cycle. The external cache is implemented with synchronous SRAMs clocked at the same frequency as the microprocessor, as ratios were not supported. It is accessed via the data bus.
Fabrication
It contained 3.8 million transistors. It was fabricated in Texas Instruments' EPIC-3 process, a 0.5 µm complementary metal–oxide–semiconductor (CMOS) process with four levels of metal. The UltraSPARC was not fabricated in a BiCMOSBiCMOS
BiCMOS is an evolved semiconductor technology that integrates two formerly separate semiconductor technologies - those of the analog bipolar junction transistor and the digital CMOS transistor - in a single integrated circuit device....
process as Texas Instruments claimed it did not scale well to 0.5 µm processes and offered little performance improvement. The process was perfected on TI's MVP digital signal processor
Digital signal processor
A digital signal processor is a specialized microprocessor with an architecture optimized for the fast operational needs of digital signal processing.-Typical characteristics:...
(DSP) with some features missing such as three levels of metal instead of four and a 0.55 feature size, before it was used to fabricate the UltraSPARC to avoid a repeat of the fabrication problems encountered with SuperSPARC
SuperSPARC
The SuperSPARC is a microprocessor that implements the SPARC V8 instruction set architecture developed by Sun Microsystems. 33 and 40 MHz versions were introduced in 1992. The SuperSPARC contained 3.1 million transistors. It was fabricated by Texas Instruments at Miho, Japan in a 0.8 micrometre...
.