Pat Villani
Encyclopedia
Pasquale "Pat" J. Villani (18 April 1954 – 27 August 2011) was an American computer programmer, author, and advocate of free software
, best known for his creation of DOS-C, a DOS
emulator
written in the C language and subsequently adapted as the kernel
of the FreeDOS
operating system
and a number of other projects including DOSEMU
for Linux
. He used to sign his edits with "patv".
His efforts started when he developed an MS-DOS
3.1-compatible interface emulator to write device drivers in the C high-level language instead of in assembly language
, as was the usual approach at that time. This interface emulator grew into a minimal operating system named XDOS around 1988.
He added an IPL to set up a boot environment before loading the actual operating system and developed an MS-DOS-compatible frontend API to applications. In contrast to MS-DOS, which is not designed to be reentrant, the system calls of his operating system were, which is often a requirement for multitasking
and real-time
applications in embedded systems. This system was named NSS-DOS and also offered commercially.
When one potential contractor sought to use the OS in a system equipped with Motorola 680x0
processors instead of Intel x86 processors, for which the system was designed originally and which utilize different instruction set
s and memory model
s, Villani was able to redesign his system to become portable across a range of different compilers and target environments. This move to a completely different target platform, while losing binary compatibility with existing applications, would have required a complete rewrite from scratch had his system not been written in a high-level language such as C, which allowed him to reuse large parts. His new DOS/NT used a microkernel
architecture with logical separation of file system
, memory
and task manager
.
Villani joined the FreeDOS project in 1994 after reading Jim Hall
's announcement of a "PD-DOS" on [news:comp.os.msdos.apps comp.os.msdos.misc.apps]. In response to Hall's announcement, Villani devised a derivative of DOS/NT named DOS-C with a monolithic kernel
and an architecture more similar to the non-multitasking MS-DOS, and in 1995 he made it available for dual-use under a GPL open-source license to become the kernel component of the new "Free-DOS" operating system, as "PD-DOS" was called at this time.
In 1996, Villani wrote the book FreeDOS Kernel, which describes the design of the DOS-C / FreeDOS kernel and the original FreeDOS COMMAND.COM
command line interpreter. The name of the operating system was subsequently officially changed to FreeDOS to reflect the spelling used in the book.
Internally, the FreeDOS kernel was still significantly different from MS-DOS, which, while no problem for embedded applications specifically written for FreeDOS, caused various compatibility issues in conjunction with misbehaving DOS applications. Villani and other contributors analyzed and addressed many of these issues over the years for FreeDOS to become much more MS-DOS compatible.
With some breaks Villani remained active with the FreeDOS project, including the preparations for the forthcoming release of FreeDOS 1.1 in 2011. Since 2009 he had also held the role of the project coordinator, but he had to step down in April 2011 for health reasons.
near Naples, Italy, grew up in Woodhaven
, New York, USA, and moved to Freehold Township, New Jersey, in 1990.
In 1976 he received his BSEE
degree from Polytechnic Institute of Brooklyn and in 1981 an MSEE degree in Electrical Engineering
from Polytechnic Institute of New York. In 2008 he also received a Master's certificate in Project Management
from George Washington University
and he was an adjunct professor at Brookdale Community College
beginning in 2010.
He previously worked for Stratus Computers, Inc.
on their Continuum fault-tolerant product line and also as a consultant for AT&T Bell Laboratories. At Digital Equipment Corporation
/ Compaq
he worked as a principal software engineer on the OSF1 / Digital UNIX / Tru64 UNIX
operating system beginning in 1995, and since 2006 had been Acting Director of Communications Infrastructure and Software Architect for Vonage
.
He was a member of M.A.R.S., A.R.R.L., and IEEE.
Free software
Free software, software libre or libre software is software that can be used, studied, and modified without restriction, and which can be copied and redistributed in modified or unmodified form either without restriction, or with restrictions that only ensure that further recipients can also do...
, best known for his creation of DOS-C, a DOS
DOS
DOS, short for "Disk Operating System", is an acronym for several closely related operating systems that dominated the IBM PC compatible market between 1981 and 1995, or until about 2000 if one includes the partially DOS-based Microsoft Windows versions 95, 98, and Millennium Edition.Related...
emulator
Emulator
In computing, an emulator is hardware or software or both that duplicates the functions of a first computer system in a different second computer system, so that the behavior of the second system closely resembles the behavior of the first system...
written in the C language and subsequently adapted as the kernel
Kernel (computing)
In computing, the kernel is the main component of most computer operating systems; it is a bridge between applications and the actual data processing done at the hardware level. The kernel's responsibilities include managing the system's resources...
of the FreeDOS
FreeDOS
FreeDOS is an operating system for IBM PC compatible computers. FreeDOS is made up of many different, separate programs that act as "packages" to the overall FreeDOS Project...
operating system
Operating system
An operating system is a set of programs that manage computer hardware resources and provide common services for application software. The operating system is the most important type of system software in a computer system...
and a number of other projects including DOSEMU
DOSEMU
DOSEMU, alternatively rendered dosemu, is a compatibility layer software package that enables MS-DOS systems, DOS clones such as FreeDOS, and DOS software to run under Linux on x86-based PCs ....
for Linux
Linux
Linux is a Unix-like computer operating system assembled under the model of free and open source software development and distribution. The defining component of any Linux system is the Linux kernel, an operating system kernel first released October 5, 1991 by Linus Torvalds...
. He used to sign his edits with "patv".
FreeDOS involvement
Villani had already been working on a DOS-like operating system for use in embedded systems for some while before the advent of FreeDOS.His efforts started when he developed an MS-DOS
MS-DOS
MS-DOS is an operating system for x86-based personal computers. It was the most commonly used member of the DOS family of operating systems, and was the main operating system for IBM PC compatible personal computers during the 1980s to the mid 1990s, until it was gradually superseded by operating...
3.1-compatible interface emulator to write device drivers in the C high-level language instead of in assembly language
Assembly language
An assembly language is a low-level programming language for computers, microprocessors, microcontrollers, and other programmable devices. It implements a symbolic representation of the machine codes and other constants needed to program a given CPU architecture...
, as was the usual approach at that time. This interface emulator grew into a minimal operating system named XDOS around 1988.
He added an IPL to set up a boot environment before loading the actual operating system and developed an MS-DOS-compatible frontend API to applications. In contrast to MS-DOS, which is not designed to be reentrant, the system calls of his operating system were, which is often a requirement for multitasking
Computer multitasking
In computing, multitasking is a method where multiple tasks, also known as processes, share common processing resources such as a CPU. In the case of a computer with a single CPU, only one task is said to be running at any point in time, meaning that the CPU is actively executing instructions for...
and real-time
Real-time computing
In computer science, real-time computing , or reactive computing, is the study of hardware and software systems that are subject to a "real-time constraint"— e.g. operational deadlines from event to system response. Real-time programs must guarantee response within strict time constraints...
applications in embedded systems. This system was named NSS-DOS and also offered commercially.
When one potential contractor sought to use the OS in a system equipped with Motorola 680x0
Motorola 68000
The Motorola 68000 is a 16/32-bit CISC microprocessor core designed and marketed by Freescale Semiconductor...
processors instead of Intel x86 processors, for which the system was designed originally and which utilize different 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...
s and memory model
Memory model
The Intel x86 cpu has six memory models which control how the segment registers are used and the default size of pointers.- Memory segmentation :Four registers are used to refer to four segments on the 16-bit x86 segmented memory architecture...
s, Villani was able to redesign his system to become portable across a range of different compilers and target environments. This move to a completely different target platform, while losing binary compatibility with existing applications, would have required a complete rewrite from scratch had his system not been written in a high-level language such as C, which allowed him to reuse large parts. His new DOS/NT used a microkernel
Microkernel
In computer science, a microkernel is the near-minimum amount of software that can provide the mechanisms needed to implement an operating system . These mechanisms include low-level address space management, thread management, and inter-process communication...
architecture with logical separation of file system
File system
A file system is a means to organize data expected to be retained after a program terminates by providing procedures to store, retrieve and update data, as well as manage the available space on the device which contain it. A file system organizes data in an efficient manner and is tuned to the...
, memory
DOS memory management
In IBM PC compatible computing, DOS memory management refers to software and techniques employed to give applications access to more than 640K of "conventional memory". The 640kB limit was specific to the IBM PC and close compatibles; other machines running MS-DOS had different limits, for example...
and task manager
Task manager
A task manager is a program used to provide information about the processes and programs running on a computer, as well as the general status of the computer. It can also be used to terminate processes and programs, as well as change the processes priority...
.
Jim Hall (programmer)
Jim Hall is a computer programmer and advocate of free software, best known for his work on FreeDOS. Hall began writing the free replacement for the MS-DOS operating system in 1994 when he was still a physics student at the University of Wisconsin-River Falls...
's announcement of a "PD-DOS" on [news:comp.os.msdos.apps comp.os.msdos.misc.apps]. In response to Hall's announcement, Villani devised a derivative of DOS/NT named DOS-C with a monolithic kernel
Monolithic kernel
A monolithic kernel is an operating system architecture where the entire operating system is working in the kernel space and alone as supervisor mode...
and an architecture more similar to the non-multitasking MS-DOS, and in 1995 he made it available for dual-use under a GPL open-source license to become the kernel component of the new "Free-DOS" operating system, as "PD-DOS" was called at this time.
In 1996, Villani wrote the book FreeDOS Kernel, which describes the design of the DOS-C / FreeDOS kernel and the original FreeDOS COMMAND.COM
COMMAND.COM
COMMAND.COM is the filename of the default operating system shell for DOS operating systems and the default command line interpreter on Windows 95, Windows 98 and Windows Me...
command line interpreter. The name of the operating system was subsequently officially changed to FreeDOS to reflect the spelling used in the book.
Internally, the FreeDOS kernel was still significantly different from MS-DOS, which, while no problem for embedded applications specifically written for FreeDOS, caused various compatibility issues in conjunction with misbehaving DOS applications. Villani and other contributors analyzed and addressed many of these issues over the years for FreeDOS to become much more MS-DOS compatible.
With some breaks Villani remained active with the FreeDOS project, including the preparations for the forthcoming release of FreeDOS 1.1 in 2011. Since 2009 he had also held the role of the project coordinator, but he had to step down in April 2011 for health reasons.
Biography
Villani was born in Nocera InferioreNocera Inferiore
Nocera Inferiore, formerly Nocera dei Pagani, is a town and comune in Campania, Italy, in the province of Salerno, at the foot of Monte Albino, 20 km east-south-east of Naples by rail.-History:...
near Naples, Italy, grew up in Woodhaven
Woodhaven, Queens
Woodhaven is a middle-class neighborhood located in the borough of Queens in New York City, New York, United States.Woodhaven is bordered on the north by a public park, Forest Park, and Park Lane South. Woodhaven also borders Richmond Hill to the east, and Ozone Park to the south at Atlantic Avenue...
, New York, USA, and moved to Freehold Township, New Jersey, in 1990.
In 1976 he received his BSEE
Bachelor of Engineering
The Bachelor of Engineering is an undergraduate academic degree awarded to a student after three to five years of studying engineering at universities in Armenia, Australia, Bangladesh, Bulgaria, Canada, China, Denmark, Egypt, Finland , Germany, Hong Kong, India, Indonesia, Ireland, Jordan, Korea,...
degree from Polytechnic Institute of Brooklyn and in 1981 an MSEE degree in Electrical Engineering
Electrical engineering
Electrical engineering is a field of engineering that generally deals with the study and application of electricity, electronics and electromagnetism. The field first became an identifiable occupation in the late nineteenth century after commercialization of the electric telegraph and electrical...
from Polytechnic Institute of New York. In 2008 he also received a Master's certificate in Project Management
Project management
Project management is the discipline of planning, organizing, securing, and managing resources to achieve specific goals. A project is a temporary endeavor with a defined beginning and end , undertaken to meet unique goals and objectives, typically to bring about beneficial change or added value...
from George Washington University
George Washington University
The George Washington University is a private, coeducational comprehensive university located in Washington, D.C. in the United States...
and he was an adjunct professor at Brookdale Community College
Brookdale Community College
Brookdale Community College is an accredited coeducational public community college in Lincroft, Monmouth County, New Jersey. Brookdale Community College was founded in 1967 and has Higher Education Centers in Neptune, Freehold, Hazlet, Long Branch, Sandy Hook, and Wall.Brookdale is an...
beginning in 2010.
He previously worked for Stratus Computers, Inc.
Stratus Technologies
Stratus Technologies, Inc. a major producer of fault tolerant computer servers. The company was founded in 1980 as Stratus Computer, Inc. in Natick, Massachusetts, and adopted its present name in 1999. The current CEO and president is Dave Laurello. Stratus Technologies, Inc. is a privately held...
on their Continuum fault-tolerant product line and also as a consultant for AT&T Bell Laboratories. At Digital Equipment Corporation
Digital Equipment Corporation
Digital Equipment Corporation was a major American company in the computer industry and a leading vendor of computer systems, software and peripherals from the 1960s to the 1990s...
/ Compaq
Compaq
Compaq Computer Corporation is a personal computer company founded in 1982. Once the largest supplier of personal computing systems in the world, Compaq existed as an independent corporation until 2002, when it was acquired for US$25 billion by Hewlett-Packard....
he worked as a principal software engineer on the OSF1 / Digital UNIX / Tru64 UNIX
Tru64 UNIX
Tru64 UNIX is a 64-bit UNIX operating system for the Alpha instruction set architecture , currently owned by Hewlett-Packard . Previously, Tru64 UNIX was a product of Compaq, and before that, Digital Equipment Corporation , where it was known as Digital UNIX .As its original name suggests, Tru64...
operating system beginning in 1995, and since 2006 had been Acting Director of Communications Infrastructure and Software Architect for Vonage
Vonage
Vonage is a publicly held commercial voice over IP network and SIP company that provides telephone service via a broadband connection. The company's name is a play on their motto "Voice-Over-Net-AGE"....
.
He was a member of M.A.R.S., A.R.R.L., and IEEE.