picoJava is a

microprocessor A microprocessor is a computer processor where the data processing logic and control is included on a single integrated circuit, or a small number of integrated circuits. The microprocessor contains the arithmetic, logic, and control circu ...

specification dedicated to native execution of

Java bytecode In computing, Java bytecode is the bytecode-structured instruction set of the Java virtual machine (JVM), a virtual machine that enables a computer to run programs written in the Java programming language and several other programming languages, ...

without the need for an interpreter or

just-in-time compilation In computing, just-in-time (JIT) compilation (also dynamic translation or run-time compilations) is a way of executing computer code that involves compiler, compilation during execution of a program (at run time (program lifecycle phase), run tim ...

. The aim is to speed bytecode execution up by up to 20 times, compared to standard Intel

CPU A central processing unit (CPU), also called a central processor, main processor or just processor, is the electronic circuitry that executes instructions comprising a computer program. The CPU performs basic arithmetic, logic, controlling, an ...

with a

Java virtual machine A Java virtual machine (JVM) is a virtual machine that enables a computer to run Java programs as well as programs written in other languages that are also compiled to Java bytecode. The JVM is detailed by a specification that formally describ ...

GNU Compiler Collection The GNU Compiler Collection (GCC) is an optimizing compiler produced by the GNU Project supporting various programming languages, hardware architectures and operating systems. The Free Software Foundation (FSF) distributes GCC as free sof ...

has been available until version 3.2.3 as machine definition 'pj,' probably first patch was for version 2.9.

GNU Binutils The GNU Binary Utilities, or , are a set of programming tools for creating and managing binary programs, object files, libraries, profile data, and assembly source code. Tools They were originally written by programmers at Cygnus Solutions ...

is still available as machine definition 'pj,' as of Binutil version 2.28.

GNU Debugger The GNU Debugger (GDB) is a portable debugger that runs on many Unix-like systems and works for many programming languages, including Ada, C, C++, Objective-C, Free Pascal, Fortran, Go, and partially others. History GDB was first writte ...

was once implemented, but code might be lost.

Sun Microsystems Sun Microsystems, Inc. (Sun for short) was an American technology company that sold computers, computer components, software, and information technology services and created the Java programming language, the Solaris operating system, ZFS, ...

provided

instruction set simulator An instruction set simulator (ISS) is a simulation model, usually coded in a high-level programming language, which mimics the behavior of a mainframe or microprocessor by "reading" instructions and maintaining internal variables which represent ...

worked with GDB as SCSL

open source code Open-source software (OSS) is computer software that is released under a license in which the copyright holder grants users the rights to use, study, change, and distribute the software and its source code to anyone and for any purpose. O ...

. This approach results in the fastest Java runtime performance with a small

memory footprint Memory footprint refers to the amount of main memory that a program uses or references while running. The word footprint generally refers to the extent of physical dimensions that an object occupies, giving a sense of its size. In computing, the ...

and competitive performance on code not written in the Java language. The picoJava specification does not include any

memory Memory is the faculty of the mind by which data or information is encoded, stored, and retrieved when needed. It is the retention of information over time for the purpose of influencing future action. If past events could not be remembered ...

I/O interface In computing, input/output (I/O, or informally io or IO) is the communication between an information processing system, such as a computer, and the outside world, possibly a human or another information processing system. Inputs are the signals ...

logic, so that developers can add their own logic to customize memory and an

interface Interface or interfacing may refer to: Academic journals * ''Interface'' (journal), by the Electrochemical Society * '' Interface, Journal of Applied Linguistics'', now merged with ''ITL International Journal of Applied Linguistics'' * '' Int ...

Products

picoJava was originally designed to be used in consumer electronic products that run Java applications.

never released a product based on this technology; however, Sun have licensed the technology to companies such as Fujitsu, NEC and Siemens. The

Verilog Verilog, standardized as IEEE 1364, is a hardware description language (HDL) used to model electronic systems. It is most commonly used in the design and verification of digital circuits at the register-transfer level of abstraction. It is a ...

code of picoJava was later released under SCSL

, but the download page is currently not available. In 2000

Fujitsu is a Japanese multinational information and communications technology equipment and services corporation, established in 1935 and headquartered in Tokyo. Fujitsu is the world's sixth-largest IT services provider by annual revenue, and the la ...

released the ''J-Starter Kit'', a development system featuring a picoJava Architecture processor. The open-source version of picoJava has been implemented in an

FPGA A field-programmable gate array (FPGA) is an integrated circuit designed to be configured by a customer or a designer after manufacturinghence the term ''Field-programmability, field-programmable''. The FPGA configuration is generally specifi ...

Notes

References

* McGhan, Harlan; O’Connor, Mike (October 1998). "PicoJava: A Direct Execution Engine For Java Bytecode". '' Computer'', Volume 31, Issue 10: pp. 22–30. * O’Connor, J. Michael; Tremblay, Marc (March/April 1997). "picoJava-I: The Java Virtual Machine in Hardware". ''

IEEE Micro ''IEEE Micro'' is a peer-reviewed scientific journal published by the IEEE Computer Society covering small systems and semiconductor chips, including integrated circuit processes and practices, project management, development tools and infrastruc ...

'', Volume 17, Issue 2: pp. 45–53. * Hangal, Sudheendra; O'Connor, J. Michael (May/June 1999). "Performance analysis and validation of the picoJava processor." ''

'', Volume 19, Issue 3.

External links

picoJava
at Sun Community Source Licensing (SCSL)

Java virtual machine {{Compu-hardware-stub

Products

See also

Notes

References

External links