XINU Is Not Unix (XINU, a
recursive acronym
A recursive acronym is an acronym that refers to itself, and appears most frequently in computer programming. The term was first used in print in 1979 in Douglas Hofstadter's book '' Gödel, Escher, Bach: An Eternal Golden Braid'', in which Hofs ...
), is an
operating system
An operating system (OS) is system software that manages computer hardware and software resources, and provides common daemon (computing), services for computer programs.
Time-sharing operating systems scheduler (computing), schedule tasks for ...
for
embedded system
An embedded system is a specialized computer system—a combination of a computer processor, computer memory, and input/output peripheral devices—that has a dedicated function within a larger mechanical or electronic system. It is e ...
s, originally developed by
Douglas Comer for educational use at
Purdue University
Purdue University is a Public university#United States, public Land-grant university, land-grant research university in West Lafayette, Indiana, United States, and the flagship campus of the Purdue University system. The university was founded ...
in the 1980s. The name is both recursive, and is ''
Unix
Unix (, ; trademarked as UNIX) is a family of multitasking, multi-user computer operating systems that derive from the original AT&T Unix, whose development started in 1969 at the Bell Labs research center by Ken Thompson, Dennis Ritchie, a ...
'' spelled backwards. It has been ported to many hardware platforms, including the
DEC PDP-11
The PDP–11 is a series of 16-bit minicomputers originally sold by Digital Equipment Corporation (DEC) from 1970 into the late 1990s, one of a set of products in the Programmed Data Processor (PDP) series. In total, around 600,000 PDP-11s of a ...
and
VAX
VAX (an acronym for virtual address extension) is a series of computers featuring a 32-bit instruction set architecture (ISA) and virtual memory that was developed and sold by Digital Equipment Corporation (DEC) in the late 20th century. The V ...
systems,
Motorola 68k (
Sun-2
The Sun-2 series of UNIX workstations and servers was launched by Sun Microsystems in November 1983. As the name suggests, the Sun-2 represented the second generation of Sun systems, superseding the original Sun-1 series. The Sun-2 series used ...
and
Sun-3
Sun-3 is a series of UNIX computer workstations and servers produced by Sun Microsystems, launched on September 9, 1985. The Sun-3 series are VMEbus-based systems similar to some of the earlier Sun-2 series, but using the Motorola 68020 mic ...
workstation
A workstation is a special computer designed for technical or computational science, scientific applications. Intended primarily to be used by a single user, they are commonly connected to a local area network and run multi-user operating syste ...
s,
AT&T UNIX PC
The AT&T UNIX PC is a Unix desktop computer originally developed by Convergent Technologies (later acquired by Unisys), and marketed by AT&T Information Systems in the mid- to late-1980s. The system was codenamed "Safari 4" and is also known as th ...
,
MECB), Intel
x86
x86 (also known as 80x86 or the 8086 family) is a family of complex instruction set computer (CISC) instruction set architectures initially developed by Intel, based on the 8086 microprocessor and its 8-bit-external-bus variant, the 8088. Th ...
,
PowerPC G3
The PowerPC 7xx is a family of third generation 32-bit PowerPC microprocessors designed and manufactured by IBM and Motorola (spun off as Freescale Semiconductor bought by NXP Semiconductors). This family is called the PowerPC G3 by Apple Comput ...
,
MIPS,
ARM architecture
ARM (stylised in lowercase as arm, formerly an acronym for Advanced RISC Machines and originally Acorn RISC Machine) is a family of reduced instruction set computer, RISC instruction set architectures (ISAs) for central processing unit, com ...
and
AVR (atmega328p/Arduino). Xinu was also used for some models of
Lexmark
Lexmark International, Inc. is a privately held American company that manufactures laser printers and imaging products. The company is headquartered in Lexington, Kentucky. Since 2016 it has been jointly owned by a consortium of three multination ...
printers.
Despite its name suggesting some similarity to Unix, Xinu is a different type of operating system, written with no knowledge of the Unix source code, or compatibility goals. It uses different abstractions, and
system call
In computing, a system call (syscall) is the programmatic way in which a computer program requests a service from the operating system on which it is executed. This may include hardware-related services (for example, accessing a hard disk drive ...
s, some with names matching those of Unix, but different semantics.
History
Xinu first ran on the
LSI-11
The PDP–11 is a series of 16-bit minicomputers originally sold by Digital Equipment Corporation (DEC) from 1970 into the late 1990s, one of a set of products in the Programmed Data Processor (PDP) series. In total, around 600,000 PDP-11s of al ...
platform. A
Motorola 68000
The Motorola 68000 (sometimes shortened to Motorola 68k or m68k and usually pronounced "sixty-eight-thousand") is a 16/32-bit complex instruction set computer (CISC) microprocessor, introduced in 1979 by Motorola Semiconductor Products Sector ...
port was done by Derrick Burns in 1983. A VAX port was done in 1986 by Comer and Tom Stonecypher, an
IBM PC compatible
An IBM PC compatible is any personal computer that is hardware- and software-compatible with the IBM Personal Computer (IBM PC) and its subsequent models. Like the original IBM PC, an IBM PC–compatible computer uses an x86-based central p ...
port in 1988 by Comer and Timothy Fossum, a second
Motorola 68000
The Motorola 68000 (sometimes shortened to Motorola 68k or m68k and usually pronounced "sixty-eight-thousand") is a 16/32-bit complex instruction set computer (CISC) microprocessor, introduced in 1979 by Motorola Semiconductor Products Sector ...
(Sun 3) port circa 1988 by Shawn Ostermann and Steve Chapin, a
Macintosh
Mac is a brand of personal computers designed and marketed by Apple Inc., Apple since 1984. The name is short for Macintosh (its official name until 1999), a reference to the McIntosh (apple), McIntosh apple. The current product lineup inclu ...
platform port in 1989 by Comer and Steven Munson, an
Intel 80486
The Intel 486, officially named i486 and also known as 80486, is a microprocessor introduced in 1989. It is a higher-performance follow-up to the i386, Intel 386. It represents the fourth generation of binary compatible CPUs following the Inte ...
version by John Lin in 1995, a
SPARC port by Jim Griffioen, and a
PowerPC
PowerPC (with the backronym Performance Optimization With Enhanced RISC – Performance Computing, sometimes abbreviated as PPC) is a reduced instruction set computer (RISC) instruction set architecture (ISA) created by the 1991 Apple Inc., App ...
port in 2005 and MIPS port of Embedded Xinu in 2006 by Dennis Brylow.
Later developments
Dennis Brylow at
Marquette University
Marquette University () is a Private university, private Jesuit research university in Milwaukee, Wisconsin, United States. It was established as Marquette College on August 28, 1881, by John Henni, the first Archbishop of the Roman Catholic Ar ...
has ported Xinu to both the PowerPC and MIPSEL (little-endian MIPS)
processor architectures. Porting Xinu to
reduced instruction set computing
In electronics and computer science, a reduced instruction set computer (RISC) is a computer architecture designed to simplify the individual instructions given to the computer to accomplish tasks. Compared to the instructions given to a com ...
(RISC) architectures greatly simplified its implementation, increasing its ability to be used as a tool for teaching and research.
MIPSEL was chosen as a target architecture due to the proliferation of the MIPSEL-based
WRT54GL router and the ''cool'' incentive that motivates some students to become involved in projects. The first embedded Xinu systems laboratory based on the WRT54GL router was developed at Marquette University. In collaboration with the Marquette Xinu team, an embedded Xinu laboratory was formed at the University of Mississippi, laying the groundwork for further work on developing a Virtual Xinu Laboratory.
Embedded Xinu
Embedded Xinu is a fresh reimplementation of the Xinu design, in
ANSI C
ANSI C, ISO C, and Standard C are successive standards for the C programming language published by the American National Standards Institute (ANSI) and ISO/IEC JTC 1/SC 22/WG 14 of the International Organization for Standardization (ISO) and the ...
, on an embedded RISC architecture. The MIPS port of Embedded Xinu was developed from 2006 to 2010 at Marquette University, under the direction of Dr. Dennis Brylow. The Embedded Xinu operating system is copyright (c) 2007, 2008, 2009, and 2010 by Douglas Comer and Dennis Brylow.
University of Mississippi Embedded Xinu Laboratory
The Xinu Laboratory in the University of Mississippi's Department of Computer and Information Science was formed during the summer of 2008 by Dr. Paul Ruth. Assisting him in the project were Jianshu Zhao and Patrick Hoover, who were both graduate students at the time. Also assisting him were Chelsea Norman and Kevin Kent, who were undergraduates at the time. The initial laboratory is based on the Marquette University Embedded Xinu Laboratory.
Located in the server room of Weir Hall on the campus of the University of Mississippi, is composed of a dozen modified Linksys WRT54GL wireless routers, a 32 port Digi Etherlite serial annex, a 24 port 10/100 Mbit/s
Ethernet
Ethernet ( ) is a family of wired computer networking technologies commonly used in local area networks (LAN), metropolitan area networks (MAN) and wide area networks (WAN). It was commercially introduced in 1980 and first standardized in 198 ...
switch
In electrical engineering, a switch is an electrical component that can disconnect or connect the conducting path in an electrical circuit, interrupting the electric current or diverting it from one conductor to another. The most common type o ...
, a BayTech serial controlled power strip, and quite a few wires. The system is controlled by a standard PC running Debian
Linux
Linux ( ) is a family of open source Unix-like operating systems based on the Linux kernel, an kernel (operating system), operating system kernel first released on September 17, 1991, by Linus Torvalds. Linux is typically package manager, pac ...
. The whole system cost less than $3000, not including the PC.
The WRT54G routers use the MIPSEL architecture and are used as backend devices on which the Xinu embedded operating system runs. The PC runs several daemons which enable and manage the users ability to access the backends.
Nexos Project
The Nexos Project is a joint effort between Marquette University, the
University at Buffalo
The State University of New York at Buffalo (commonly referred to as UB, University at Buffalo, and sometimes SUNY Buffalo) is a public university, public research university in Buffalo, New York, Buffalo and Amherst, New York, United States. ...
, and the
University of Mississippi
The University of Mississippi (Epithet, byname Ole Miss) is a Public university, public research university in University, near Oxford, Mississippi, United States, with a University of Mississippi Medical Center, medical center in Jackson, Miss ...
to build curriculum materials and a supporting experimental laboratory for hands-on projects in computer systems courses. The approach focuses on low cost, flexible, commodity embedded hardware, freely available development and debugging tools, and a fresh implementation of a classic operating system, Embedded Xinu, that is ideal for student exploration. Virtual Xinu addresses two challenges that limit the effectiveness of Nexos. First, potential faculty adopters have clearly indicated that even with the current minimal monetary cost of installation, the hardware modifications, and time investment remain troublesome factors that scare off interested educators. Second, overcoming inherent complications that arise due to the shared subnet that allow student projects to interfere with each other in ways that are difficult to recreate, debug, and understand. Ultimately, porting the Xinu operating systems to
QEMU
The Quick Emulator (QEMU) is a free and open-source emulator that uses dynamic binary translation to emulate a computer's processor; that is, it translates the emulated binary codes to an equivalent binary format which is executed by the mach ...
virtual hardware, and developing the virtual networking platform have produced results showing success using Virtual Xinu in the classroom during one semester of the Operating Systems course at the University of Mississippi by Dr Ruth.
Latest versions
There are several versions of Xinu available for platforms such as an x86, ARM, AVR (Arduino) and MIPS. The last versions by Douglas Comer is for both the Intel x86 (Galileo) and
ARM
In human anatomy, the arm refers to the upper limb in common usage, although academically the term specifically means the upper arm between the glenohumeral joint (shoulder joint) and the elbow joint. The distal part of the upper limb between ...
Cortex-A8 (BeagleBone Black). The version for AVR requires 32 KB of flash, thus
Arduino
Arduino () is an Italian open-source hardware and open-source software, software company, project, and user community that designs and manufactures single-board microcontrollers and microcontroller kits for building digital devices. Its hardwar ...
Uno boards and alike are supported. The source code of these versions is freely available.
Xinu avr atmega328p source code
/ref>
See also
* Minix
MINIX is a Unix-like operating system based on a microkernel Software architecture, architecture, first released in 1987 and written by American-Dutch computer scientist Andrew S. Tanenbaum. It was designed as a clone of the Unix operating syste ...
* xv6
* List of operating systems
* Timeline of operating systems
This article presents a timeline of events in the history of computer operating systems from 1951 to the current day. For a narrative explaining the overall developments, see the History of operating systems.
1950s
* 1951
** LEO I 'Lyons Elec ...
References
External links
*
Douglas Comer at Purdue University
Embedded Xinu and RISC Xinu at Marquette University
Xinu for the LSI-11 in the Unix Archive
(very old)
installation instructions
University of Mississippi embedded Xinu lab
Nexos Project
{{Operating system
Educational operating systems
Embedded operating systems
Cross-platform free software
1981 software
Computing platforms
MIPS operating systems
X86 operating systems