IBM Rivina
Encyclopedia
Rivina is an experimental 64-bit
64-bit
64-bit is a word size that defines certain classes of computer architecture, buses, memory and CPUs, and by extension the software that runs on them. 64-bit CPUs have existed in supercomputers since the 1970s and in RISC-based workstations and servers since the early 1990s...

 PowerPC
PowerPC
PowerPC is a RISC architecture created by the 1991 Apple–IBM–Motorola alliance, known as AIM...

 microprocessor
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...

 built by IBM
IBM
International Business Machines Corporation or IBM is an American multinational technology and consulting corporation headquartered in Armonk, New York, United States. IBM manufactures and sells computer hardware and software, and it offers infrastructure, hosting and consulting services in areas...

 in 2000. It was the successor to "guTS" (Gigahertz Unit Test Site) and the purpose of both was to build a processor able to reach very high frequencies. They were the first microprocessors to reach and surpass the 1 GHz mark.

Project work was conducted by fewer than twenty engineers over a course of two years. The idea was to use aggressive circuit
Integrated circuit
An integrated circuit or monolithic integrated circuit is an electronic circuit manufactured by the patterned diffusion of trace elements into the surface of a thin substrate of semiconductor material...

 design techniques, a carefully crafted floorplan and microarchitecture
Microarchitecture
In computer engineering, microarchitecture , also called computer organization, is the way a given instruction set architecture is implemented on a processor. A given ISA may be implemented with different microarchitectures. Implementations might vary due to different goals of a given design or...

 while keeping a short six stage pipeline. While guTS only supported a subset of about 100, mainly integer
Integer
The integers are formed by the natural numbers together with the negatives of the non-zero natural numbers .They are known as Positive and Negative Integers respectively...

 instructions, of the PowerPC instruction set
Instruction set
An instruction set, or instruction set architecture , is the part of the computer architecture related to programming, including the native data types, instructions, registers, addressing modes, memory architecture, interrupt and exception handling, and external I/O...

, Rivina used the complete 64-bit PowerPC specification including dual precision floating point
Floating point
In computing, floating point describes a method of representing real numbers in a way that can support a wide range of values. Numbers are, in general, represented approximately to a fixed number of significant digits and scaled using an exponent. The base for the scaling is normally 2, 10 or 16...

 and address translation. guTS had a small single cycle 4 kB L1 cache
CPU cache
A CPU cache is a cache used by the central processing unit of a computer to reduce the average time to access memory. The cache is a smaller, faster memory which stores copies of the data from the most frequently used main memory locations...

, and Rivina used a two-cycle, two set associative 64 kB cache instead.

The processor comprised over 19 million transistors, manufactured using IBM's CMOS
CMOS
Complementary metal–oxide–semiconductor is a technology for constructing integrated circuits. CMOS technology is used in microprocessors, microcontrollers, static RAM, and other digital logic circuits...

 7S, 0.22 μm copper fabrication process
CPU cache
A CPU cache is a cache used by the central processing unit of a computer to reduce the average time to access memory. The cache is a smaller, faster memory which stores copies of the data from the most frequently used main memory locations...

. It was able to reach 1.15 GHz, dissipating 112 watts at 101 °C.
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