operating system research

CS 261: Research Topics in Operating Systems (2021)

Some links to papers are links to the ACM’s site. You may need to use the Harvard VPN to get access to the papers via those links. Alternate links will be provided.

Meeting 1 (1/26): Overview

Operating system architectures, meeting 2 (1/28): multics and unix.

“Multics—The first seven years” , Corbató FJ, Saltzer JH, and Clingen CT (1972)

“Protection in an information processing utility” , Graham RM (1968)

“The evolution of the Unix time-sharing system” , Ritchie DM (1984)

Additional resources

The Multicians web site for additional information on Multics, including extensive stories and Multics source code.

Technical: The Multics input/output system , Feiertag RJ and Organick EI, for a description of Multics I/O to contrast with Unix I/O.

Unix and Multics , Tom Van Vleck.

… I remarked to Dennis that easily half the code I was writing in Multics was error recovery code. He said, "We left all that stuff out. If there's an error, we have this routine called panic() , and when it is called, the machine crashes, and you holler down the hall, 'Hey, reboot it.'"

The Louisiana State Trooper Story

The IBM 7094 and CTSS

This describes the history of the system that preceded Multics, CTSS (the Compatible Time Sharing System). It also contains one of my favorite stories about the early computing days: “IBM had been very generous to MIT in the fifties and sixties, donating or discounting its biggest scientific computers. When a new top of the line 36-bit scientific machine came out, MIT expected to get one. In the early sixties, the deal was that MIT got one 8-hour shift, all the other New England colleges and universities got a shift, and the third shift was available to IBM for its own use. One use IBM made of its share was yacht handicapping: the President of IBM raced big yachts on Long Island Sound, and these boats were assigned handicap points by a complicated formula. There was a special job deck kept at the MIT Computation Center, and if a request came in to run it, operators were to stop whatever was running on the machine and do the yacht handicapping job immediately.”

Using Ring 5 , Randy Saunders.

"All Multics User functions work in Ring 5." I have that EMail (from Dave Bergum) framed on my wall to this date. … All the documentation clearly states that system software has ring brackets of [1,5,5] so that it runs equally in both rings 4 and 5. However, the PL/I compiler creates segments with ring brackets of [4,4,4] by default. … I found each and every place CNO had fixed a program without resetting the ring brackets correctly. It started out 5 a day, and in 3 months it was down to one a week.”

Bell Systems Technical Journal 57(6) Part 2: Unix Time-sharing System (July–August 1978)

This volume contains some of the first broadly-accessible descriptions of Unix. Individual articles are available on archive.org . As of late January 2021, you can buy a physical copy on Amazon for $2,996. Interesting articles include Thompson on Unix implementation, Ritchie’s retrospective, and several articles on actual applications, especially document preparation.

Meeting 3 (2/2): Microkernels

“The nucleus of a multiprogramming system” , Brinch Hansen P (1970).

“Toward real microkernels” , Liedtke J (1996).

“Are virtual machine monitors microkernels done right?” , Hand S, Warfield A, Fraser K, Kotsovinos E, Magenheimer DJ (2005).

Supplemental reading

“Improving IPC by kernel design” , Liedtke J (1993). Article introducing the first microbenchmark-performant microkernel.

“Are virtual machine monitors microkernels done right?” , Heiser G, Uhlig V, LeVasseur J (2006).

“From L3 to seL4: What have we learnt in 20 years of L4 microkernels?” , Elphinstone K, Heiser G (2013).

Retained: Minimality as key design principle. Replaced: Synchronous IPC augmented with (seL4, NOVA, Fiasco.OC) or replaced by (OKL4) asynchronous notification. Replaced: Physical by virtual message registers. Abandoned: Long IPC. Replaced: Thread IDs by port-like IPC endpoints as message destinations. Abandoned: IPC timeouts in seL4, OKL4. Abandoned: Clans and chiefs. Retained: User-level drivers as a core feature. Abandoned: Hierarchical process management. Multiple approaches: Some L4 kernels retain the model of recursive address-space construc- tion, while seL4 and OKL4 originate mappings from frames. Added: User-level control over kernel memory in seL4, kernel memory quota in Fiasco.OC. Unresolved: Principled, policy-free control of CPU time. Unresolved: Handling of multicore processors in the age of verification. Replaced: Process kernel by event kernel in seL4, OKL4 and NOVA. Abandoned: Virtual TCB addressing. … Abandoned: C++ for seL4 and OKL4.

Meeting 4 (2/4): Exokernels

“Exterminate all operating systems abstractions” , Engler DE, Kaashoek MF (1995).

“Exokernel: an operating system architecture for application-level resource management” , Engler DE, Kaashoek MF, O’Toole J (1995).

“The nonkernel: a kernel designed for the cloud” , Ben-Yehuda M, Peleg O, Ben-Yehuda OA, Smolyar I, Tsafrir D (2013).

“Application performance and flexibility on exokernel systems” , Kaashoek MF, Engler DR, Ganger GR, Briceño HM, Hunt R, Mazières D, Pinckney T, Grimm R, Jannotti J, Mackenzie K (1997).

Particularly worth reading is section 4, Multiplexing Stable Storage, which contains one of the most overcomplicated designs for stable storage imaginable. It’s instructive: if your principles end up here, might there be something wrong with your principles?

“Fast and flexible application-level networking on exokernel systems” , Ganger GR, Engler DE, Kaashoek MF, Briceño HM, Hunt R, Pinckney T (2002).

Particularly worth reading is section 8, Discussion: “The construction and revision of the Xok/ExOS networking support came with several lessons and controversial design decisions.”

Meeting 5 (2/9): Security

“EROS: A fast capability system” , Shapiro JS, Smith JM, Farber DJ (1999).

“Labels and event processes in the Asbestos operating system” , Vandebogart S, Efstathopoulos P, Kohler E, Krohn M, Frey C, Ziegler D, Kaashoek MF, Morris R, Mazières D (2007).

This paper covers too much ground. On the first read, skip sections 4–6.

Meeting 6 (2/11): I/O

“Arrakis: The operating system is the control plane” (PDF) , Peter S, Li J, Zhang I, Ports DRK, Woos D, Krishnamurthy A, Anderson T, Roscoe T (2014)

“The IX Operating System: Combining Low Latency, High Throughput, and Efficiency in a Protected Dataplane” , Belay A, Prekas G, Primorac M, Klimovic A, Grossman S, Kozyrakis C, Bugnion E (2016) — read Sections 1–4 first (return to the rest if you have time)

“I'm Not Dead Yet!: The Role of the Operating System in a Kernel-Bypass Era” , Zhang I, Liu J, Austin A, Roberts ML, Badam A (2019)

• “The multikernel: A new OS architecture for scalable multicore systems” , Baumann A, Barham P, Dagand PE, Harris T, Isaacs R, Peter S, Roscoe T, Schüpach A, Singhana A (2009); this describes the Barrelfish system on which Arrakis is based

Meeting 7 (2/16): Speculative designs

From least to most speculative:

“Unified high-performance I/O: One Stack to Rule Them All” (PDF) , Trivedi A, Stuedi P, Metzler B, Pletka R, Fitch BG, Gross TR (2013)

“The Case for Less Predictable Operating System Behavior” (PDF) , Sun R, Porter DE, Oliveira D, Bishop M (2015)

“Quantum operating systems” , Corrigan-Gibbs H, Wu DJ, Boneh D (2017)

“Pursue robust indefinite scalability” , Ackley DH, Cannon DC (2013)

Meeting 8 (2/18): Log-structured file system

“The Design and Implementation of a Log-Structured File System” , Rosenblum M, Ousterhout J (1992)

“Logging versus Clustering: A Performance Evaluation”

• Read the abstract of the paper ; scan further if you’d like
• Then poke around the linked critiques

Meeting 9 (2/23): Consistency

“Generalized file system dependencies” , Frost C, Mammarella M, Kohler E, de los Reyes A, Hovsepian S, Matsuoka A, Zhang L (2007)

“Application crash consistency and performance with CCFS” , Sankaranarayana Pillai T, Alagappan R, Lu L, Chidambaram V, Arpaci-Dusseau AC, Arpaci-Dusseau RH (2017)

Meeting 10 (2/25): Transactions and speculation

“Rethink the sync” , Nightingale EB, Veeraraghavzn K, Chen PM, Flinn J (2006)

“Operating system transactions” , Porter DE, Hofmann OS, Rossbach CJ, Benn E, Witchel E (2009)

Meeting 11 (3/2): Speculative designs

“Can We Store the Whole World's Data in DNA Storage?”

“A tale of two abstractions: The case for object space”

“File systems as processes”

“Preserving hidden data with an ever-changing disk”

More, if you’re hungry for it

• “Breaking Apart the VFS for Managing File Systems”

Virtualization

Meeting 14 (3/11): virtual machines and containers.

“Xen and the Art of Virtualization” , Barham P, Dragovic B, Fraser K, Hand S, Harris T, Ho A, Neugebauer R, Pratt I, Warfield A (2003)

“Blending containers and virtual machines: A study of Firecracker and gVisor” , Anjali, Caraz-Harter T, Swift MM (2020)

Meeting 15 (3/18): Virtual memory and virtual devices

“Memory resource management in VMware ESX Server” , Waldspurger CA (2002)

“Opportunistic flooding to improve TCP transmit performance in virtualized clouds” , Gamage S, Kangarlou A, Kompella RR, Xu D (2011)

Meeting 16 (3/23): Speculative designs

“The Best of Both Worlds with On-Demand Virtualization” , Kooburat T, Swift M (2011)

“The NIC is the Hypervisor: Bare-Metal Guests in IaaS Clouds” , Mogul JC, Mudigonda J, Santos JR, Turner Y (2013)

“vPipe: One Pipe to Connect Them All!” , Gamage S, Kompella R, Xu D (2013)

“Scalable Cloud Security via Asynchronous Virtual Machine Introspection” , Rajasekaran S, Ni Z, Chawla HS, Shah N, Wood T (2016)

Distributed systems

Meeting 17 (3/25): distributed systems history.

“Grapevine: an exercise in distributed computing” , Birrell AD, Levin R, Schroeder MD, Needham RM (1982)

“Implementing remote procedure calls” , Birrell AD, Nelson BJ (1984)

Skim : “Time, clocks, and the ordering of events in a distributed system” , Lamport L (1978)

Meeting 18 (3/30): Paxos

“Paxos made simple” , Lamport L (2001)

“Paxos made live: an engineering perspective” , Chanra T, Griesemer R, Redston J (2007)

“In search of an understandable consensus algorithm” , Ongaro D, Ousterhout J (2014)

• Adrian Colyer’s consensus series links to ten papers, especially:
• “Raft Refloated: Do we have consensus?” , Howard H, Schwarzkopf M, Madhavapeddy A, Crowcroft J (2015)
• A later update from overlapping authors: “Paxos vs. Raft: Have we reached consensus on distributed consensus?” , Howard H, Mortier R (2020)
• “Understanding Paxos” , notes by Paul Krzyzanowski (2018); includes some failure examples
• One-slide Paxos pseudocode , Robert Morris (2014)

Meeting 19 (4/1): Review of replication results

Meeting 20 (4/6): project discussion, meeting 21 (4/8): industrial consistency.

“Scaling Memcache at Facebook” , Nishtala R, Fugal H, Grimm S, Kwiatkowski M, Lee H, Li HC, McElroy R, Paleczny M, Peek D, Saab P, Stafford D, Tung T, Venkataramani V (2013)

“Millions of Tiny Databases” , Brooker M, Chen T, Ping F (2020)

Meeting 22 (4/13): Short papers and speculative designs

“Scalability! But at what COST?” , McSherry F, Isard M, Murray DG (2015)

“What bugs cause production cloud incidents?” , Liu H, Lu S, Musuvathi M, Nath S (2019)

“Escape Capsule: Explicit State Is Robust and Scalable” , Rajagopalan S, Williams D, Jamjoom H, Warfield A (2013)

“Music-defined networking” , Hogan M, Esposito F (2018)

• Too networking-centric for us, but fun: “Delay is Not an Option: Low Latency Routing in Space” , Handley M (2018)
• A useful taxonomy: “When Should The Network Be The Computer?” , Ports DRK, Nelson J (2019)

Meeting 23 (4/20): The M Group

“All File Systems Are Not Created Equal: On the Complexity of Crafting Crash-Consistent Applications” , Pillai TS, Chidambaram V, Alagappan R, Al-Kiswany S, Arpaci-Dusseau AC, Arpaci-Dusseau RH (2014)

“Crash Consistency Validation Made Easy” , Jiang Y, Chen H, Qin F, Xu C, Ma X, Lu J (2016)

Meeting 24 (4/22): NVM and Juice

“Persistent Memcached: Bringing Legacy Code to Byte-Addressable Persistent Memory” , Marathe VJ, Seltzer M, Byan S, Harris T

“NVMcached: An NVM-based Key-Value Cache” , Wu X, Ni F, Zhang L, Wang Y, Ren Y, Hack M, Shao Z, Jiang S (2016)

“Cloudburst: stateful functions-as-a-service” , Sreekanti V, Wu C, Lin XC, Schleier-Smith J, Gonzalez JE, Hellerstein JM, Tumanov A (2020)

• Adrian Colyer’s take

Meeting 25 (4/27): Scheduling

• “The Linux Scheduler: A Decade of Wasted Cores” , Lozi JP, Lepers B, Funston J, Gaud F, Quéma V, Fedorova A (2016)

Computer Science

Operating systems.

The role of operating systems has evolved over time, from sharing one device’s resources among many users in the mainframe era, to providing convenient user interface, storage, and networking abstractions in the personal computer era. As we transition to the ubiquitous computing era, operating systems must now manage a user’s information and computation across many computers and devices. Yale is developing new operating system architectures, application environments, and security frameworks to meet today’s challenges across the computing spectrum, including IoT devices, cyber-physical systems (such as self-driving cars and quadcopters), cloud computers, and blockchain ecosystems.

Faculty working in this area:

Highlights in this area:.

Abhishek Bhattacharjee and his students are buildinging next-generation operating systems for emerging heterogeneous computer systems. The waning of Moore’s Law and Dennard scaling as well as the widespread success of AI have prompted systems designers to embrace heterogeneity in hardware. Today’s systems integrate tightly- and loosely-coupled accelerators, ranging from GPUs, TPUs, neural network hardware, DSPs, etc., a swath of heterogeneous memory devices, ranging from high-bandwidth to non-volatile memories, with a complex amalgam of operating systems, drivers, firmware, runtimes, and languages. Abhishek’s group studies the hardware/software interface and the OS abstractions best suited to make these complex systems programmable.

Anurag Khandelwal and his team are exploring the design for an Operating System stack for emerging serverless and disaggregated architectures. Over the last few years, significant improvements in inter-server network performance, coupled with stagnating intra-server interconnect performance, have driven advances in data center resource disaggregation — where server compute, memory and storage resources are physically separated into network attached resource “blades”. However, actualizing the benefits of resource disaggregation while ensuring application performance requires operating system (OS) support. Unfortunately, existing approaches expose a hard tradeoff between application performance on one hand and resource elasticity on the other. Anurag’s group is exploring a fundamentally new network-centric design for the disaggregated OS — one that places resource management and access functionality in the data center network fabric to break the above tradeoff.

Zhong Shao   and his FLINT team at Yale are working to develop a new class of formally verified operating systems for modern heterogeneous platforms. In the last few years, they have made multiple breakthroughs showing that building a hacker-resistant concurrent OS kernel is not only feasible but also practical. They developed a novel language-based account of certified concurrent abstraction layers, advocated abstraction over a particularly rich class of specification (called deep specification), and then constructed new methodologies and tools for formally specifying, programming, verifying, and composing abstraction layers.  They have successfully developed the CertiKOS operating system and verified its contextual functional correctness in Coq. CertiKOS is written in 6500 lines of C and x86 assembly and runs on stock x86 multicore machines. This is the world’s first proof of functional correctness of a complete, general-purpose concurrent OS kernel with fine-grained locking. Shao and his team are now working on expanding the CertiKOS infrastructure so it can be applied to support more advanced system software for modern heterogeneous platforms and distributed enclaves. 

Lin Zhong and his team are examining some foundational assumptions made by modern OSes in the context of mobile and edge computing. First, modern OSes assume permissive and weak languages such as C; as a result, they feature complex, error-prone mechanisms to ensure correctness at runtime, leading to poor efficiency and availability. Using the Rust language, Lin’s team has constructed an experimental OS called Theseus to explore the power of language and compiler-based mechanisms. Theseus enforces many correctness invariants and even realize traditional OS-based functions at compile-time. Second, modern OSes assume complete trust from the user and their applications and as a result, they have unfettered access to application data by design. Lin’s team is exploring both incremental changes to existing OSes, e.g., Linux, and clean-slate designs to decouple virtualization, the essential role of OS, from data access.

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Musings on Operating Systems Research

Rather than burying the lineup after a heap of verbiage, I thought it made more sense to put the lineup right up front. Then I will get busy with musing about research as well as learning about operating systems.

• Cory Lueninghoener, working with a vast cast of past LISA chairs, steering committee members, and USENIX staff, put together a history of the LISA conference. With pictures!
• Laura Nolan reviews Marianne Bellotti's recently published book Kill It With Fire, that addresses modernizing legacy systems with an unusual twist.
• Jacob Scott discusses some of the 'failure modes' that can happen when Service Level Objectives (SLOs) are imposed in a top-down fashion, in response to an earlier article by Laura Nolan.
• Thomas Depierre, also responding to Laura Nolan's article about SLOs, argues that SRE can bridge the gap between high-level metrics that management requires and the contextual service-specific knowledge that engineering teams have.
• Rik Farrow interviews Vasily Tarasov, who explains his journey from Russia and Linux kernel work, to Stony Brook where he changed his focus to file systems and storage, and to working for IBM.
• Hugo Lefeuvre, Gaulthier Gain, Daniel Dinca, Alexander Jung, Simon Kuenzer, Vlad Bădoiu, Răzvan Deaconescu , Laurent Mathy, Costin Raiciu, Pierre Olivier, Felipe Huici write about the Unikraft project. Sponsered by the Linux Foundation, Unikraft is toolset for building mostly-Linux API compatible unikernels, suitable for running as virtual machines and featuring faster startup and performance and stronger security.
• Rik Farrow reviews Gabriel Gambetta's Computer Graphics from Scratch, a book that really explain how modern graphics programming works starting with the simplest possible function that writes one pixel in color.
• Ghada Almashaqbeh revisits old ideas about peer-assisted models for resource trading, the author investigates the use of cryptocurrencies for building decentralized services.

The Trouble with Operating Systems Research

That brings us to the next point, that Linux has taken over OS research. Roscoe points out that it is very difficult to get OS research published, and if you want to get a research paper past program committee members you better build on Linux. He then provides examples, using all three OS papers at two years of Operating Systems Design and Implementation (OSDI). That's right, three papers on OS design, all based on improvements to Linux. In OSDI'21, a quarter of the conference was devoted to machine learning and only six percent (two papers) to OS design.

ETH Zurich uses an NXP system-on-chip (SoC) for their operating system class, one with a plethora of different processors on board. Just looking at the chip layout, I found it hard to imagine where to even start writing an OS. But the server world provides a clue: the board management controller (BMC) handles testing, booting, and maintenance tasks on server board, and BMCs currently run Linux. Not that you usually had any access to this core running Linux as a Linux system, but it is key to booting your servers.

Roscoe does a much better job than I am at calling for OS research and providing reasons for doing so than I can. I'm happy he stuck his neck out to make these points, and I wanted to both thank him as well as draw attention to what he has done. But I also wanted to throw my own thoughts into the ring.

Linux, like Windows, is a one-size-fits-all operating system, something that runs on Rasberry Pi's and supercomputers (noting that Windows doesn't have the same span, but the same OS kernel runs on laptops and servers). Running a complex OS on an IoT device makes no sense at all, but it is often the easiest thing to do when one is familiar with that OS. Sort of like using a jackhammer for tacking up a photograph, because you are unfamiliar with the use of a tack hammer. Linux or Windows do provide the programmer with familiar APIs, and that's the reason they get used: not because they are the best fit, but because they are familiar.

Perhaps what we need instead of today's monolithic, monstrous, operating systems is some basic scaffolding, something that students, researchers, and programmers can use to actually build a better fitting operating system upon. I've often written about microkernels as one design space, and Roscoe even mentions using seL4 to replace Linux in the BMC. That's a great idea, but I think it's just a start.

After all, we do need some place to start from. Right now, supercomputers work like this, with each processing unit having simple network communication, some memory to work in, and an 'OS' that consists of a program that receives the instructions to execute, data to work on, starts the instructions, then sends back the results. No 350 system call API and device drivers for just about any IO device ever made — just the basics.

As a post-graduate, I took an operating systems class. The lab used PDP 11/45s, with a system architecture that did look a lot like the PDP 6. I thought I was supposed to write an operating system that semester, and was flumoxxed to see other students in the lab with two boxes of punchcards (yes punchcards!) indicating that they already had close to 4000 lines of working code. I didn't know that they had been working on the immense project of creating a very simple OS, something akin to CP/M, over multiple semesters. For comparison, the first release of Linux was a little over 10K lines of code, but is over 25.5 million lines of code today.

Today, I find it hard to imagine even learning how Linux works in a single semester, or writing an operating system that does as much as we were asked to do on the PDP 11/45: write device drivers for the terminal and disk controller, write a file system, and execute code loaded from that file system. The PDP 11/45, as I remember it, was a model of simplicity. For example, the disk controller included DMA support and all the programmer needed to do is to provide a memory address, a physical disk address (cylinder, sector, head triplet), and a command. The terminal interface was an interrupt handler, just a few lines of code. Still, for someone whose interface to a computer had been handing a card deck to an operator, this was still immensely confusing. I wonder how well the ETH OS students do with the NXP SoC? I think a version of my lab today would mean using a network interface instead of a disk device, and the NXP SoC does provide a network interface.

Rik Farrow has been a consultant for 40 years. He has written two books, as well as worked as the technical editor for two editions of a popular operating system book. He also taught UNIX system administration and Internet security during the 90s, and worked as a volunteer for USENIX program and steering committees. Rik has been the editor of ;login: since 2005.

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Why are some of these

While the plan was that the, nitpick: pdp-7, not pdp-6., norm is right: it was a pdp-7, s/i can imaging/i can image/, thanks. i fixed the typo,.

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Fifty years of the personal computer operating system, by david laws | april 18, 2024.

PC software pioneer Gary Kildall demonstrated CP/M, the first commercially successful personal computer operating system in Pacific Grove, California, in 1974. Following is the story of how his company, Digital Research Inc., established CP/M as an industry standard and its subsequent loss to a version from Microsoft that copied the look and feel of the DRI software.

Gary Arlen Kildall was born to a family of Scandinavian descent in Seattle, Washington, in 1942. His inventive skills flourished in repairing automobiles and having fun but suffered in scholastic pursuits. He qualified for admission to the University of Washington based on his teaching experience at the family-owned Kildall Nautical School rather than his high school grades.

Dorothy and Gary, circa 1978. Photo: Courtesy Kildall Family

Gary entered college and married his high school sweetheart Dorothy McEwen in 1963. He was one of 20 students accepted into the university's first master's program in computer science. Here, his mathematical talents were applied to a subject that fascinated him: all-night sessions programming a new Burroughs computer. To avoid the uncertainty of the draft at the height of the Vietnam War, on graduating with a PhD, he entered a US Navy officer training school and was posted to serve as an instructor in computer science at the Naval Postgraduate School (NPS) in Monterey, California.

Herrmann Hall, Naval Postgraduate School, Monterey. Creative Commons CC0 1.0 Universal Public Domain Dedication.

Gary remained at NPS as an associate professor after his tour of duty ended in 1972. He became fascinated with Intel Corporation's first microprocessor chip and simulated its operation on the school's IBM mainframe computer. This work earned him a consulting relationship with the company to develop PL/M, a high-level programming language that played a significant role in establishing Intel as the dominant supplier of chips for personal computers.

To design software tools for Intel's second-generation processor, he needed to connect to a new 8" floppy disk-drive storage unit from Memorex. He wrote code for the necessary interface software that he called CP/M (Control Program for Microcomputers) in a few weeks, but his efforts to build the electronic hardware required to transfer the data failed. The project languished for a year. Frustrated, he called electronic engineer John Torode, a college friend then teaching at UC Berkeley, who crafted a "beautiful rat's nest of wirewraps, boards and cables" for the task.

This is going to be a "big thing"

Late one afternoon in the fall of 1974, together with John Torode, in the backyard workshop of his home at 781 Bayview Avenue, Pacific Grove, Gary "loaded my CP/M program from paper tape to the diskette and 'booted' CP/M from the diskette, and up came the prompt: *."

"This may have been one of the most exciting days of my life, except, of course, when I visited Niagara Falls," he exclaimed. We now have the power of an IBM S/370 [mainframe computer] at our fingertips." This is going to be a "big thing," they told each other and "retired for the evening to take on the simpler task of emptying a jug of not-so-good red wine … and speculating on the future of our new software tool." 

By successfully booting a computer from a floppy disk drive, they had given birth to an operating system that, together with the microprocessor and the disk drive, would provide one of the key building blocks of the personal computer revolution. While they knew it was important, neither realized the extraordinary impact it would have on their lives and times.

781 Bayview Avenue, Pacific Grove, circa 1974. Photo: Courtesy Kildall Family

As Intel expressed no interest in CP/M, Gary was free to exploit the program on his own and sold the first license in 1975. He continued teaching part-time at NPS, and in 1976, with his wife Dorothy as cofounder, they established Intergalactic Digital Research to pursue commercial opportunities. They shortened the company name to Digital Research Inc. (DRI) when it became available.

Glenn Ewing, a former NPS student, approached DRI with the opportunity to license CP/M for a new family of disk subsystems for fast-growing microcomputer maker IMSAI Inc. Reluctant to adapt the code for another controller, Gary worked with Glen Ewing to split out the hardware dependent-portions so they could be incorporated into a separate piece of code called the BIOS (Basic Input Output System).

Before CP/M, computer manufacturers designed their operating systems to work only with their own hardware and peripheral equipment. An IBM OS would only work with IBM computers; a Burroughs OS would only work with Burroughs computers, etc. Applications had to be written for each computer's specific OS. Such "closed systems" made it difficult or impossible to mix and match the best pieces of equipment and software applications programs from different manufacturers.

The BIOS code allowed all Intel and compatible microprocessor-based computers from other manufacturers to run CP/M on any new hardware. This capability stimulated the rise of an independent software industry by expanding the market's potential size for each product. A single program could run without modification on computers supplied by multiple manufacturers, laying an essential foundation for the personal computer revolution.

DRI advertisement from 1978

Dorothy and Gary opened their first office at 716 Lighthouse Avenue, Pacific Grove, on the upper floor, with a view of Monterey Bay. They sold CP/M disks via mail order and walked to the post office every workday to pick up checks resulting from ads placed in industry magazines such as Byte and Dr. Dobbs' Journal of Computer Calisthenics and Orthodontia.

A licensing deal with computer manufacturer IMSAI bestowed credibility across the industry. CP/M became accepted as a standard and was offered by most early personal computer vendors, including pioneers Altair, Amstrad, Kaypro, and Osborne.

Outside the DRI office at 801 Lighthouse Avenue in November 1980. Photo: John Pierce

In 1978, revenue topped $100,00 per month, and DRI purchased a Victorian house at 801 Lighthouse Avenue for the company headquarters. By 1980, DRI employed more than 20 people, and Fortune magazine reported that the company generated revenue of $3.5 million, five times the revenue of Microsoft at that time. Gary also acquired a Piper aircraft that allowed him to fly from Monterey to meet regularly with his customers in Silicon Valley and beyond.

To accommodate the expanding engineering staff hired to service the hundreds of different computer models used by more than a million people worldwide, DRI purchased a 1909 American Foursquare-style residence at 734 Lighthouse. Today, it houses the offices of the Carmel Pine Cone newspaper.

Gary in 734 Lighthouse Avenue. Photo: John Pierce

One Friday afternoon, Gary called the engineering staff together and announced that he would give them all a raise over the weekend. On Monday, when they returned to work, contractors began raising the building to make room in the basement for a new Digital Equipment Corporation VAX 11/750 computer system. After several weeks, supported by heavy wooden beams and house jacks, the engineers' desks were five feet higher.

By 1983, DRI's annual sales reached $45 million. The company employed over 500 people, including more than 100 engineers, and had expanded into another building at 160 Central Avenue, which today houses the Monterey Bay Aquarium's offices.

The IBM PC Effect

In 1980, IBM established a new business division in Boca Raton, Florida, to develop a desktop computer for the mass market. To get the IBM PC, as it became known, to market as quickly as possible, they used commercially available components, including an Intel microprocessor chip. Bill Gates knew Gary from early discussions about merging their companies and setting up shop in Pacific Grove, so when an IBM procurement team visited Microsoft to license the BASIC interpreter program, he referred them to DRI for an operating system.

Gary at Monterey Airport with his Piper Aerostar. Photo: Tom Rolander

When the IBM team arrived in Pacific Grove, they met in the morning with Dorothy and DRI attorney Gerry Davis to agree on the terms of a non-disclosure agreement. Gary, who had flown his aircraft to Oakland to meet an important customer, returned in the afternoon, as scheduled, to discuss technical matters. IBM wished to purchase CP/M outright, whereas DRI sought a per-copy royalty payment in order to protect its existing base of business. The meeting ended in an impasse over financial terms, but Gary believed they had essentially agreed to do business. 

Kildall tried to renew the negotiations a couple of weeks later. IBM did not respond because, in the meantime, Bill Gates purchased an OS from Seattle Computer Products that was written to emulate the look and feel of CP/M. He then sold a one-time, non-exclusive license to IBM, which used the designation PC DOS. With great foresight, he retained the right to license the product to others as MS-DOS.

When Gary learned of this transaction, he threatened IBM with a lawsuit over what he believed was an illegal copy of CP/M. IBM responded by agreeing to fund DRI to adapt CP/M for the PC and to make both brands of OS available to customers. With CP/M's reputation and enhanced features, DRI believed customers would opt for the better product.

IBM announced the PC on August 12, 1981, but with the PC-DOS list price set at $40 versus $240 for CP/M, most customers simply chose the former as the lower-cost option. Attorney Gerry Davis recalled that "IBM clearly betrayed the impression they gave Gary and me."

DRI continued to thrive for several years with a multi-tasking operating system for the IBM PC-XT and a host of new products. The company also introduced operating systems with windowing capability and menu-driven user interfaces years before Apple and Microsoft.

At its peak, DRI employed over 500 people and opened operations in Asia and Europe. However, by the mid-1980s, in the struggle with the juggernaut created by the combined efforts of IBM and Microsoft, DRI had lost the basis of its operating systems business.

Dispirited, Gary, who never relished the responsibility of managing a large company or displayed the cut-throat business acumen of a Gates, sold the company to Novell Inc. of Provo, Utah, in 1991. Ultimately, Novell closed the California operation and, in 1996, disposed of the assets to Caldera, Inc., which used DRI intellectual property assets to prevail in a lawsuit against Microsoft.

In other pursuits, Gary founded KnowledgeSet with his friend and DRI VP of engineering, Tom Rolander, where they created the first CD-ROM encyclopedia for Grolier.

In an oral history for the Computer History Museum, Brian Halla, Intel's technical liaison to DRI, recalls that Gary "showed me this VAX 11/780 that he had running in his basement, and he was so proud of it, and he said, 'I figured out a way to have a computer generate animation,' and he said, 'Watch this. And he runs a demo of a Coke bottle that starts real slowly and starts spinning, and so as maybe several months went by, he lost interest in this, and he sold his setup to a little company called Pixar.'"

Kildall continued to innovate after selling DRI. He moved to Austin, Texas, where he founded Prometheus Light and Sound to explore wireless home networking technology and participated in charitable work for pediatric AIDS.

Gary Kildall died in 1996 at age 52 following an accident in Monterey. His ashes are buried in Seattle, the hometown he shared with Bill Gates. Dorothy McEwan Kildall purchased the Holman Ranch in Carmel Valley and served on many community boards, including the Heritage Society of Pacific Grove. She died in 2005.

The Legacy of Gary Kildall

In 1995, the Software and Information Industry Association presented Gary Kildall with a posthumous Lifetime Achievement Award, citing eight significant areas in which he contributed to the microcomputer industry.

In an obituary published in the Microprocessor Report in 1994, his friend, the late John Wharton, commented, "I don't think Gary ever really begrudged Bill Gates his business success or his personal fortune. … what I think Gary wanted most was to share his excitement and enthusiasm for computers and technology with others."

Gary Kildall in 1988 Photo: Copyright Tom O'Neal, Carmel Valley, CA

On April 25, 2014, the Institute of Electrical and Electronic Engineering, "The world's largest professional association for the advancement of technology," installed a bronze IEEE Milestone in Electrical Engineering and Computing plaque outside the former DRI headquarters at 801 Lighthouse Avenue. The Milestone program honors important events in electrical engineering and computing. Achievements such as Thomas Edison's electric light bulb, Marconi's wireless communications, and Bell Labs' first transistor are recognized with plaques in appropriate locations.

The citation reads: "Dr. Gary A. Kildall demonstrated the first working prototype of CP/M (Control Program for Microcomputers) in Pacific Grove in 1974. Together with his invention of the BIOS (Basic Input Output System), Kildall's operating system allowed a microprocessor-based computer to communicate with a disk drive storage unit and provided an important foundation for the personal computer revolution."

In 2017, US Navy dignitaries, friends, family, and peers gathered to celebrate the dedication of the Gary A. Kildall Conference Room on the Naval Postgraduate School campus in Monterey. The ceremony included the installation of a duplicate of the IEEE plaque in the conference room.

Despite this wide recognition of his technical accomplishments, Gary's legacy remains mired in a tangle of myths and conspiracy theories. The most persistent being driven by a 1982 comment attributed to Bill Gates and published in the London Times newspaper that "Gary was out flying when IBM came to visit, and that's why they did not get the contract."

The former editor of the Times , Harold Evans, atoned for that story in a PBS documentary and his book They Made America: Two Centuries of Innovators from the Steam Engine to the Search Engine . The subtitle of the chapter on Gary, "He saw the future and made it work. He was the true founder of the personal computer revolution and the father of PC software," offers a sympathetic telling of the life and times of the entrepreneurial genius who helped give birth to the PC operating system 50 years ago this year.

Additional information at the Computer History Museum 

Comments in quotes in this article without source attribution are from Gary's unpublished draft of Computer Connections: People, Places, and Events in the Evolution of the Personal Computer Industry , written in 1993. The Kidall family has authorized the online publication of extracts from this memoir in the blog Gary Kidall: In His Own Words .

The Computer History Museum has also made the source code of several early releases of CP/M available for non-commercial use.

A search for "Kildall" in the CHM collection catalog yields 45 records comprising objects, documents, and images, including a video of the 2014 CP/M IEEE Milestone Dedication event .

Main image: Gary Kildall at the first West Coast Computer Faire in the San Francisco Civic Auditorium in 1977. [CHM Object ID: 500004174 © Tom Munnecke/Hulton Archive/Getty Images]

About the author.

David A. Laws [AMD 1975-1986, V.P. Business Development] is a high-technology business consultant with a focus on marketing and strategic planning. He earned a B.Sc. (Physics) in the UK and after moving to California in 1968 worked for Silicon Valley companies, including Fairchild Semiconductor, Advanced Micro Devices (AMD), and Altera Corporation, in roles from product marketing engineer to CEO.

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Title: machine learning for windows malware detection and classification: methods, challenges and ongoing research.

Abstract: In this chapter, readers will explore how machine learning has been applied to build malware detection systems designed for the Windows operating system. This chapter starts by introducing the main components of a Machine Learning pipeline, highlighting the challenges of collecting and maintaining up-to-date datasets. Following this introduction, various state-of-the-art malware detectors are presented, encompassing both feature-based and deep learning-based detectors. Subsequent sections introduce the primary challenges encountered by machine learning-based malware detectors, including concept drift and adversarial attacks. Lastly, this chapter concludes by providing a brief overview of the ongoing research on adversarial defenses.

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New report puts Android vs iOS security to the test — here’s the winner

It's the one you think it is according to new research

Most people think Apple's devices beat Android in smartphone security , especially in the never ending debate on Android versus iPhone . Researchers have decided to test that notion, and while Apple's smartphones do appear to be more secure than the competition, the iPhone is far from a perfectly locked-down device in terms of security issues.

Ernestas Naprys of Cybernews performed the research by taking a brand new iPhone and Android phone and installing the top 100 free apps from each platform's app store. He also created new social media accounts and authorized them in apps that would allow it.

From there, he let the phones sit idle for five days and tracked how often they connected to foreign servers and where the servers were. Interestingly, the iPhone sent more server queries than Android—3,308 daily versus 2,323. 

Don't let the number fool you, though. While Apple sent almost 1,000 more queries, 60% of them went directly to Apple, where they're safer. On Android, only 24% went to Google, with the rest going to third-party servers worldwide. For example, the iPhone averaged one Russian server daily, and the Android phone averaged 13. For Chinese servers , the iPhone didn't contact any, while the Android connected to five per day.

Overall, the iPhone was pickier about which servers it contacted despite the overall number being higher. With Facebook, the iPhone connected 20 times a day compared to almost 200 times daily for the Android phone. 

To track when server queries were sent and where they were sent to, Naprys used a private Domain Name System (DNS) . 

You don't necessarily need to be alarmed about the state of your Android or iPhone and its security, but it's something to think about. 

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The Cybernews team said, "This by itself is not something that is unusual or very suspicious. These endpoints are used quite often in apps to track which ads users have watched, app usage, search patterns, and others. While this is a common practice, it does raise serious privacy and security concerns." 

"While the data that is collected by these services is generally not that sensitive, however, journalists, activists, opposition, or other people that could be of interest to governments should take this extremely seriously and be careful. They should avoid using such apps or, at the very least, block traffic tracking services," the team continued.

If you are concerned about your phone sending out requests to countries like Russia and China, you might want to stick with an iPhone . It's not perfect, but it does seem to be a little more thoughtful about choosing safe places and sticking with its own servers when possible. There are also privacy focused phones, like the Punkt phone introduced earlier this year at CES 2024 , which uses an open-source code version of Android.

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Dave LeClair is the Senior News Editor for Tom's Guide, keeping his finger on the pulse of all things technology. He loves taking the complicated happenings in the tech world and explaining why they matter. Whether Apple is announcing the next big thing in the mobile space or a small startup advancing generative AI, Dave will apply his experience to help you figure out what's happening and why it's relevant to your life.

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