{"id":98477,"date":"2026-04-28T09:00:00","date_gmt":"2026-04-28T16:00:00","guid":{"rendered":""},"modified":"2026-04-28T09:12:32","modified_gmt":"2026-04-28T16:12:32","slug":"continuing-the-story-of-early-dos-development","status":"publish","type":"post","link":"https:\/\/opensource.microsoft.com\/blog\/2026\/04\/28\/continuing-the-story-of-early-dos-development\/","title":{"rendered":"Continuing the story of early DOS development"},"content":{"rendered":"\n<p>Over the last few years, we\u2019ve been working to open some of the earliest chapters of Microsoft\u2019s operating system history. In 2018 we (re)-open-sourced MS\u2011DOS 1.25 and 2.11, and more recently in 2024 we were able to make the <a href=\"https:\/\/opensource.microsoft.com\/blog\/2024\/04\/25\/open-sourcing-ms-dos-4-0\" target=\"_blank\" rel=\"noreferrer noopener\">source for MS\u2011DOS 4.0<\/a> available to the public as well. Today, on 86-DOS 1.00\u2019s 45th anniversary, we\u2019re continuing that tradition by preserving <a href=\"https:\/\/github.com\/DOS-History\/Paterson-Listings\" target=\"_blank\" rel=\"noreferrer noopener\">the earliest DOS source code<\/a> discovered to date. These releases are about making historically important systems software available for study, preservation, and plain ol\u2019 curiosity.<\/p>\n\n\n\n<div class=\"wp-block-buttons is-content-justification-center is-layout-flex wp-container-core-buttons-is-layout-16018d1d wp-block-buttons-is-layout-flex\">\n<div class=\"wp-block-button\"><a class=\"wp-block-button__link wp-element-button\" href=\"https:\/\/github.com\/DOS-History\/Paterson-Listings\" target=\"_blank\" rel=\"noreferrer noopener\">Explore listings and code at DOS-History\/Paterson-Listings<\/a><\/div>\n<\/div>\n\n\n\n<p>But that work doesn&#8217;t end with a GitHub repo. Software history lives in code, yes, but also in scanned listings, internal documents, assembler printouts, and the sometimes wonderfully analog artifacts of how operating systems came together in the late 1970s and early 1980s. If you read the original announcement around <a href=\"https:\/\/devblogs.microsoft.com\/commandline\/re-open-sourcing-ms-dos-1-25-and-2-0\/\" target=\"_blank\" rel=\"noreferrer noopener\">re\u2011open sourcing MS\u2011DOS 1.25 and 2.0 on the Windows Command Line blog<\/a> you\u2019ll know how much context matters when trying to understand where today\u2019s platforms came from.<\/p>\n\n\n\n<p>We\u2019re stoked today to showcase some newly available source code materials that provide an even earlier look into the development of PC-DOS 1.00, the first release of DOS for the IBM PC. A dedicated team of historians and preservationists led by <a href=\"https:\/\/thebrokenpipe.com\/about\/\" target=\"_blank\" rel=\"noreferrer noopener\">Yufeng Gao<\/a> and <a href=\"http:\/\/cini.classiccmp.org\/\" target=\"_blank\" rel=\"noreferrer noopener\">Rich Cini<\/a> has worked to locate, scan, and transcribe the stack of <a href=\"https:\/\/github.com\/microsoft\/MS-DOS\/blob\/main\/v1.25\/Tim_Paterson_16Dec2013_email.txt\" target=\"_blank\" rel=\"noreferrer noopener\">DOS-era source listings<\/a> from Tim Paterson, the author of DOS.<\/p>\n\n\n\n<p>The listings include sources to the 86-DOS 1.00 kernel, several development snapshots of the PC-DOS 1.00 kernel, and some well-known utilities such as CHKDSK. Not only were these assembler listings, but there were also listings of the assembler itself! This work offers rare insight into how MS-DOS\/PC-DOS came to be, and how operating system development was done at the time, not as it was later reconstructed.<\/p>\n\n\n<figure data-wp-context=\"{&quot;imageId&quot;:&quot;69f10df9bc5dc&quot;}\" data-wp-interactive=\"core\/image\" class=\"wp-block-image aligncenter size-full wp-lightbox-container\"><img decoding=\"async\" data-wp-class--hide=\"state.isContentHidden\" data-wp-class--show=\"state.isContentVisible\" data-wp-init=\"callbacks.setButtonStyles\" data-wp-on-async--click=\"actions.showLightbox\" data-wp-on-async--load=\"callbacks.setButtonStyles\" data-wp-on-async-window--resize=\"callbacks.setButtonStyles\" src=\"https:\/\/opensource.microsoft.com\/blog\/wp-content\/uploads\/2026\/04\/86-DOS-artifact-and-IBM-PC.webp\" alt=\"Image of an 86-DOS artifact next to an IBM PC.\" class=\"wp-image-98479 webp-format\" srcset=\"\" data-orig-src=\"https:\/\/opensource.microsoft.com\/blog\/wp-content\/uploads\/2026\/04\/86-DOS-artifact-and-IBM-PC.webp\"><button\n\t\t\tclass=\"lightbox-trigger\"\n\t\t\ttype=\"button\"\n\t\t\taria-haspopup=\"dialog\"\n\t\t\taria-label=\"Enlarge\"\n\t\t\tdata-wp-init=\"callbacks.initTriggerButton\"\n\t\t\tdata-wp-on-async--click=\"actions.showLightbox\"\n\t\t\tdata-wp-style--right=\"state.imageButtonRight\"\n\t\t\tdata-wp-style--top=\"state.imageButtonTop\"\n\t\t>\n\t\t\t<svg xmlns=\"http:\/\/www.w3.org\/2000\/svg\" width=\"12\" height=\"12\" fill=\"none\" viewBox=\"0 0 12 12\">\n\t\t\t\t<path fill=\"#fff\" d=\"M2 0a2 2 0 0 0-2 2v2h1.5V2a.5.5 0 0 1 .5-.5h2V0H2Zm2 10.5H2a.5.5 0 0 1-.5-.5V8H0v2a2 2 0 0 0 2 2h2v-1.5ZM8 12v-1.5h2a.5.5 0 0 0 .5-.5V8H12v2a2 2 0 0 1-2 2H8Zm2-12a2 2 0 0 1 2 2v2h-1.5V2a.5.5 0 0 0-.5-.5H8V0h2Z\" \/>\n\t\t\t<\/svg>\n\t\t<\/button><\/figure>\n\n\n\n<p class=\"has-text-align-center\"><em>What&nbsp;DOS development on the IBM PC&nbsp;looked&nbsp;like&nbsp;in the early 80s.&nbsp;Credits: Rich Cini.<\/em><\/p>\n\n\n\n<p>It\u2019s also worth noting that these materials aren\u2019t just operating system releases in the traditional sense. In several cases, the listings represent point\u2011in\u2011time working states and hand-written notes, preserved by Tim Paterson himself. Think of them as a printed commit history of a Git repository. They create a timeline of changes, showing which features were implemented when, what errors were made, and how they were fixed. Soon you&#8217;ll be able to visit these living artifacts at the <a href=\"https:\/\/icm.museum\/\" target=\"_blank\" rel=\"noreferrer noopener\">Interim Computer Museum<\/a> as they&#8217;ve been generously donated by Tim Paterson.<\/p>\n\n\n\n<p>We want to thank everyone involved in curating and bringing these materials forward in a responsible and accessible way. This kind of software archaeology takes real effort across legal review, archival work, and technical validation, and it\u2019s an important part of preserving the shared history of our industry.<\/p>\n\n\n\n<p>If you&#8217;re interested in digging into these early listings yourself, we encourage you to check out the full posts from the team on <a href=\"https:\/\/thebrokenpipe.com\/dos\/paterson_listings\" target=\"_blank\" rel=\"noreferrer noopener\">Yufeng\u2019s website<\/a> and <a href=\"http:\/\/cini.classiccmp.org\/recoveryblog.htm\">Rich\u2019s website<\/a>, as well as <a href=\"https:\/\/jscarsbrook.me\/doshistory\/\" target=\"_blank\" rel=\"noreferrer noopener\">Joshua\u2019s research<\/a> on printer listing OCR. For an insiders\u2019 look at the process, explore the scanned listings and OCR&#8217;ed code at <a href=\"https:\/\/github.com\/DOS-History\/Paterson-Listings\" target=\"_blank\" rel=\"noreferrer noopener\">DOS-History\/Paterson-Listings<\/a>, which we\u2019ve worked with the maintainers to license under MIT via pull request for researchers, hobbyists, and enthusiasts like us!<\/p>\n\n\n<div class=\"wp-block-msxcm-cta-block\" data-moray data-bi-an=\"CTA Block\">\n\t<div class=\"card d-block mx-ng mx-md-0\">\n\t\t<div class=\"row no-gutters material-color-brand-dark bg-fabric-green\">\n\n\t\t\t\t\t\t\t<div class=\"col-md-4\">\n\t\t\t\t\t<img loading=\"lazy\" decoding=\"async\" width=\"1024\" height=\"768\" src=\"https:\/\/opensource.microsoft.com\/blog\/wp-content\/uploads\/2026\/03\/CLO25b-Developer-Office-1-1024x768.jpg\" class=\"card-img img-object-cover\" alt=\"Developer working in an office\" srcset=\"https:\/\/opensource.microsoft.com\/blog\/wp-content\/uploads\/2026\/03\/CLO25b-Developer-Office-1-1024x768.jpg 1024w, https:\/\/opensource.microsoft.com\/blog\/wp-content\/uploads\/2026\/03\/CLO25b-Developer-Office-1-388x291.jpg 388w, https:\/\/opensource.microsoft.com\/blog\/wp-content\/uploads\/2026\/03\/CLO25b-Developer-Office-1-768x576.jpg 768w, https:\/\/opensource.microsoft.com\/blog\/wp-content\/uploads\/2026\/03\/CLO25b-Developer-Office-1-1536x1152.jpg 1536w, https:\/\/opensource.microsoft.com\/blog\/wp-content\/uploads\/2026\/03\/CLO25b-Developer-Office-1-2048x1536.jpg 2048w, https:\/\/opensource.microsoft.com\/blog\/wp-content\/uploads\/2026\/03\/CLO25b-Developer-Office-1-450x338.jpg 450w, https:\/\/opensource.microsoft.com\/blog\/wp-content\/uploads\/2026\/03\/CLO25b-Developer-Office-1-650x488.jpg 650w\" sizes=\"auto, (max-width: 1024px) 100vw, 1024px\" \/>\t\t\t\t<\/div>\n\t\t\t\n\t\t\t<div class=\"d-flex col-md\">\n\t\t\t\t<div class=\"card-body align-self-center p-4 p-md-5\">\n\t\t\t\t\t\n\t\t\t\t\t<h2>Explore listings and code<\/h2>\n\n\t\t\t\t\t<div class=\"mb-3\">\n\t\t\t\t\t\t<p>Dig into the DOS-History\/Paterson-Listings today.<\/p>\n\t\t\t\t\t<\/div>\n\n\t\t\t\t\t\t\t\t\t\t\t<div class=\"link-group\">\n\t\t\t\t\t\t\t<a href=\"https:\/\/github.com\/DOS-History\/Paterson-Listings\" class=\"btn btn-link text-decoration-none p-0\" target=\"_blank\">\n\t\t\t\t\t\t\t\t<span>See more<\/span>\n\t\t\t\t\t\t\t\t<span class=\"glyph-append glyph-append-chevron-right glyph-append-xsmall\"><\/span>\n\t\t\t\t\t\t\t<\/a>\n\t\t\t\t\t\t<\/div>\n\t\t\t\t\t\t\t\t\t<\/div>\n\t\t\t<\/div>\n\n\t\t\t\t\t<\/div>\n\t<\/div>\n<\/div>\n","protected":false},"excerpt":{"rendered":"<p>In 2018 we (re)-open-sourced MS\u2011DOS 1.25 and 2.11, and more recently in 2024 we were able to make the source for MS\u2011DOS 4.0 available to the public as well. Today, on 86-DOS 1.00\u2019s 45th anniversary, we\u2019re continuing that tradition with the earliest DOS source code discovered to date.<\/p>\n","protected":false},"author":6277,"featured_media":98478,"comment_status":"closed","ping_status":"closed","sticky":false,"template":"","format":"standard","meta":{"msxcm_post_with_no_image":false,"ep_exclude_from_search":false,"_classifai_error":"","_classifai_text_to_speech_error":"","footnotes":""},"post_tag":[2611],"content-type":[361],"topic":[],"programming-languages":[],"coauthors":[2618,2137],"class_list":["post-98477","post","type-post","status-publish","format-standard","has-post-thumbnail","hentry","tag-azure-open-source","content-type-project-updates","review-flag-1593580428-734","review-flag-1-1593580432-963","review-flag-2-1593580437-411","review-flag-4-1593580448-609","review-flag-micro-1680215167-604"],"yoast_head":"<!-- This site is optimized with the Yoast SEO plugin v27.2 - https:\/\/yoast.com\/product\/yoast-seo-wordpress\/ -->\n<title>Continuing the story of early DOS development | Microsoft Open Source Blog<\/title>\n<meta name=\"robots\" content=\"index, follow, max-snippet:-1, max-image-preview:large, max-video-preview:-1\" \/>\n<link rel=\"canonical\" href=\"https:\/\/opensource.microsoft.com\/blog\/2026\/04\/28\/continuing-the-story-of-early-dos-development\/\" \/>\n<meta property=\"og:locale\" content=\"en_US\" \/>\n<meta property=\"og:type\" content=\"article\" \/>\n<meta property=\"og:title\" content=\"Continuing the story of early DOS development | Microsoft Open Source Blog\" \/>\n<meta property=\"og:description\" content=\"In 2018 we (re)-open-sourced MS\u2011DOS 1.25 and 2.11, and more recently in 2024 we were able to make the source for MS\u2011DOS 4.0 available to the public as well. Today, on 86-DOS 1.00\u2019s 45th anniversary, we\u2019re continuing that tradition with the earliest DOS source code discovered to date.\" \/>\n<meta property=\"og:url\" content=\"https:\/\/opensource.microsoft.com\/blog\/2026\/04\/28\/continuing-the-story-of-early-dos-development\/\" \/>\n<meta property=\"og:site_name\" content=\"Microsoft Open Source Blog\" \/>\n<meta property=\"article:published_time\" content=\"2026-04-28T16:00:00+00:00\" \/>\n<meta property=\"article:modified_time\" content=\"2026-04-28T16:12:32+00:00\" \/>\n<meta property=\"og:image\" content=\"https:\/\/opensource.microsoft.com\/blog\/wp-content\/uploads\/2026\/04\/86-DOS-Changelist.png\" \/>\n\t<meta property=\"og:image:width\" content=\"1260\" \/>\n\t<meta property=\"og:image:height\" content=\"708\" \/>\n\t<meta property=\"og:image:type\" content=\"image\/png\" \/>\n<meta name=\"author\" content=\"Stacey Haffner, Scott Hanselman\" \/>\n<meta name=\"twitter:card\" content=\"summary_large_image\" \/>\n<meta name=\"twitter:image\" content=\"https:\/\/opensource.microsoft.com\/blog\/wp-content\/uploads\/2026\/04\/86-DOS-Changelist.png\" \/>\n<meta name=\"twitter:creator\" content=\"@OpenAtMicrosoft\" \/>\n<meta name=\"twitter:site\" content=\"@OpenAtMicrosoft\" \/>\n<meta name=\"twitter:label1\" content=\"Written by\" \/>\n\t<meta name=\"twitter:data1\" content=\"Stacey Haffner, Scott Hanselman\" \/>\n\t<meta name=\"twitter:label2\" content=\"Est. reading time\" \/>\n\t<meta name=\"twitter:data2\" content=\"2 min read\" \/>\n<script type=\"application\/ld+json\" class=\"yoast-schema-graph\">{\"@context\":\"https:\/\/schema.org\",\"@graph\":[{\"@type\":\"Article\",\"@id\":\"https:\/\/opensource.microsoft.com\/blog\/2026\/04\/28\/continuing-the-story-of-early-dos-development\/#article\",\"isPartOf\":{\"@id\":\"https:\/\/opensource.microsoft.com\/blog\/2026\/04\/28\/continuing-the-story-of-early-dos-development\/\"},\"author\":[{\"@id\":\"https:\/\/opensource.microsoft.com\/blog\/author\/stacey-haffner\/\",\"@type\":\"Person\",\"@name\":\"Stacey Haffner\"},{\"@id\":\"https:\/\/opensource.microsoft.com\/blog\/author\/scott-hanselman\/\",\"@type\":\"Person\",\"@name\":\"Scott Hanselman\"}],\"headline\":\"Continuing the story of early DOS development\",\"datePublished\":\"2026-04-28T16:00:00+00:00\",\"dateModified\":\"2026-04-28T16:12:32+00:00\",\"mainEntityOfPage\":{\"@id\":\"https:\/\/opensource.microsoft.com\/blog\/2026\/04\/28\/continuing-the-story-of-early-dos-development\/\"},\"wordCount\":556,\"publisher\":{\"@id\":\"https:\/\/opensource.microsoft.com\/blog\/#organization\"},\"image\":{\"@id\":\"https:\/\/opensource.microsoft.com\/blog\/2026\/04\/28\/continuing-the-story-of-early-dos-development\/#primaryimage\"},\"thumbnailUrl\":\"https:\/\/opensource.microsoft.com\/blog\/wp-content\/uploads\/2026\/04\/86-DOS-Changelist.webp\",\"keywords\":[\"Azure Open Source\"],\"inLanguage\":\"en-US\"},{\"@type\":\"WebPage\",\"@id\":\"https:\/\/opensource.microsoft.com\/blog\/2026\/04\/28\/continuing-the-story-of-early-dos-development\/\",\"url\":\"https:\/\/opensource.microsoft.com\/blog\/2026\/04\/28\/continuing-the-story-of-early-dos-development\/\",\"name\":\"Continuing the story of early DOS development | Microsoft Open Source Blog\",\"isPartOf\":{\"@id\":\"https:\/\/opensource.microsoft.com\/blog\/#website\"},\"primaryImageOfPage\":{\"@id\":\"https:\/\/opensource.microsoft.com\/blog\/2026\/04\/28\/continuing-the-story-of-early-dos-development\/#primaryimage\"},\"image\":{\"@id\":\"https:\/\/opensource.microsoft.com\/blog\/2026\/04\/28\/continuing-the-story-of-early-dos-development\/#primaryimage\"},\"thumbnailUrl\":\"https:\/\/opensource.microsoft.com\/blog\/wp-content\/uploads\/2026\/04\/86-DOS-Changelist.webp\",\"datePublished\":\"2026-04-28T16:00:00+00:00\",\"dateModified\":\"2026-04-28T16:12:32+00:00\",\"breadcrumb\":{\"@id\":\"https:\/\/opensource.microsoft.com\/blog\/2026\/04\/28\/continuing-the-story-of-early-dos-development\/#breadcrumb\"},\"inLanguage\":\"en-US\",\"potentialAction\":[{\"@type\":\"ReadAction\",\"target\":[\"https:\/\/opensource.microsoft.com\/blog\/2026\/04\/28\/continuing-the-story-of-early-dos-development\/\"]}]},{\"@type\":\"ImageObject\",\"inLanguage\":\"en-US\",\"@id\":\"https:\/\/opensource.microsoft.com\/blog\/2026\/04\/28\/continuing-the-story-of-early-dos-development\/#primaryimage\",\"url\":\"https:\/\/opensource.microsoft.com\/blog\/wp-content\/uploads\/2026\/04\/86-DOS-Changelist.webp\",\"contentUrl\":\"https:\/\/opensource.microsoft.com\/blog\/wp-content\/uploads\/2026\/04\/86-DOS-Changelist.webp\",\"width\":1260,\"height\":708,\"caption\":\"Image of an 86-DOS Changelist.\"},{\"@type\":\"BreadcrumbList\",\"@id\":\"https:\/\/opensource.microsoft.com\/blog\/2026\/04\/28\/continuing-the-story-of-early-dos-development\/#breadcrumb\",\"itemListElement\":[{\"@type\":\"ListItem\",\"position\":1,\"name\":\"Home\",\"item\":\"https:\/\/opensource.microsoft.com\/blog\/\"},{\"@type\":\"ListItem\",\"position\":2,\"name\":\"Continuing the story of early DOS development\"}]},{\"@type\":\"WebSite\",\"@id\":\"https:\/\/opensource.microsoft.com\/blog\/#website\",\"url\":\"https:\/\/opensource.microsoft.com\/blog\/\",\"name\":\"Microsoft Open Source Blog\",\"description\":\"Open dialogue about openness at Microsoft \u2013 open source, standards, interoperability\",\"publisher\":{\"@id\":\"https:\/\/opensource.microsoft.com\/blog\/#organization\"},\"potentialAction\":[{\"@type\":\"SearchAction\",\"target\":{\"@type\":\"EntryPoint\",\"urlTemplate\":\"https:\/\/opensource.microsoft.com\/blog\/?s={search_term_string}\"},\"query-input\":{\"@type\":\"PropertyValueSpecification\",\"valueRequired\":true,\"valueName\":\"search_term_string\"}}],\"inLanguage\":\"en-US\"},{\"@type\":\"Organization\",\"@id\":\"https:\/\/opensource.microsoft.com\/blog\/#organization\",\"name\":\"Microsoft Open Source Blog\",\"url\":\"https:\/\/opensource.microsoft.com\/blog\/\",\"logo\":{\"@type\":\"ImageObject\",\"inLanguage\":\"en-US\",\"@id\":\"https:\/\/opensource.microsoft.com\/blog\/#\/schema\/logo\/image\/\",\"url\":\"https:\/\/opensource.microsoft.com\/blog\/wp-content\/uploads\/2019\/08\/Microsoft-Logo.png\",\"contentUrl\":\"https:\/\/opensource.microsoft.com\/blog\/wp-content\/uploads\/2019\/08\/Microsoft-Logo.png\",\"width\":259,\"height\":194,\"caption\":\"Microsoft Open Source Blog\"},\"image\":{\"@id\":\"https:\/\/opensource.microsoft.com\/blog\/#\/schema\/logo\/image\/\"},\"sameAs\":[\"https:\/\/x.com\/OpenAtMicrosoft\"]}]}<\/script>\n<!-- \/ Yoast SEO plugin. -->","yoast_head_json":{"title":"Continuing the story of early DOS development | Microsoft Open Source Blog","robots":{"index":"index","follow":"follow","max-snippet":"max-snippet:-1","max-image-preview":"max-image-preview:large","max-video-preview":"max-video-preview:-1"},"canonical":"https:\/\/opensource.microsoft.com\/blog\/2026\/04\/28\/continuing-the-story-of-early-dos-development\/","og_locale":"en_US","og_type":"article","og_title":"Continuing the story of early DOS development | Microsoft Open Source Blog","og_description":"In 2018 we (re)-open-sourced MS\u2011DOS 1.25 and 2.11, and more recently in 2024 we were able to make the source for MS\u2011DOS 4.0 available to the public as well. Today, on 86-DOS 1.00\u2019s 45th anniversary, we\u2019re continuing that tradition with the earliest DOS source code discovered to date.","og_url":"https:\/\/opensource.microsoft.com\/blog\/2026\/04\/28\/continuing-the-story-of-early-dos-development\/","og_site_name":"Microsoft Open Source Blog","article_published_time":"2026-04-28T16:00:00+00:00","article_modified_time":"2026-04-28T16:12:32+00:00","og_image":[{"width":1260,"height":708,"url":"https:\/\/opensource.microsoft.com\/blog\/wp-content\/uploads\/2026\/04\/86-DOS-Changelist.png","type":"image\/png"}],"author":"Stacey Haffner, Scott Hanselman","twitter_card":"summary_large_image","twitter_image":"https:\/\/opensource.microsoft.com\/blog\/wp-content\/uploads\/2026\/04\/86-DOS-Changelist.png","twitter_creator":"@OpenAtMicrosoft","twitter_site":"@OpenAtMicrosoft","twitter_misc":{"Written by":"Stacey Haffner, Scott Hanselman","Est. reading time":"2 min read"},"schema":{"@context":"https:\/\/schema.org","@graph":[{"@type":"Article","@id":"https:\/\/opensource.microsoft.com\/blog\/2026\/04\/28\/continuing-the-story-of-early-dos-development\/#article","isPartOf":{"@id":"https:\/\/opensource.microsoft.com\/blog\/2026\/04\/28\/continuing-the-story-of-early-dos-development\/"},"author":[{"@id":"https:\/\/opensource.microsoft.com\/blog\/author\/stacey-haffner\/","@type":"Person","@name":"Stacey Haffner"},{"@id":"https:\/\/opensource.microsoft.com\/blog\/author\/scott-hanselman\/","@type":"Person","@name":"Scott Hanselman"}],"headline":"Continuing the story of early DOS development","datePublished":"2026-04-28T16:00:00+00:00","dateModified":"2026-04-28T16:12:32+00:00","mainEntityOfPage":{"@id":"https:\/\/opensource.microsoft.com\/blog\/2026\/04\/28\/continuing-the-story-of-early-dos-development\/"},"wordCount":556,"publisher":{"@id":"https:\/\/opensource.microsoft.com\/blog\/#organization"},"image":{"@id":"https:\/\/opensource.microsoft.com\/blog\/2026\/04\/28\/continuing-the-story-of-early-dos-development\/#primaryimage"},"thumbnailUrl":"https:\/\/opensource.microsoft.com\/blog\/wp-content\/uploads\/2026\/04\/86-DOS-Changelist.webp","keywords":["Azure Open Source"],"inLanguage":"en-US"},{"@type":"WebPage","@id":"https:\/\/opensource.microsoft.com\/blog\/2026\/04\/28\/continuing-the-story-of-early-dos-development\/","url":"https:\/\/opensource.microsoft.com\/blog\/2026\/04\/28\/continuing-the-story-of-early-dos-development\/","name":"Continuing the story of early DOS development | Microsoft Open Source Blog","isPartOf":{"@id":"https:\/\/opensource.microsoft.com\/blog\/#website"},"primaryImageOfPage":{"@id":"https:\/\/opensource.microsoft.com\/blog\/2026\/04\/28\/continuing-the-story-of-early-dos-development\/#primaryimage"},"image":{"@id":"https:\/\/opensource.microsoft.com\/blog\/2026\/04\/28\/continuing-the-story-of-early-dos-development\/#primaryimage"},"thumbnailUrl":"https:\/\/opensource.microsoft.com\/blog\/wp-content\/uploads\/2026\/04\/86-DOS-Changelist.webp","datePublished":"2026-04-28T16:00:00+00:00","dateModified":"2026-04-28T16:12:32+00:00","breadcrumb":{"@id":"https:\/\/opensource.microsoft.com\/blog\/2026\/04\/28\/continuing-the-story-of-early-dos-development\/#breadcrumb"},"inLanguage":"en-US","potentialAction":[{"@type":"ReadAction","target":["https:\/\/opensource.microsoft.com\/blog\/2026\/04\/28\/continuing-the-story-of-early-dos-development\/"]}]},{"@type":"ImageObject","inLanguage":"en-US","@id":"https:\/\/opensource.microsoft.com\/blog\/2026\/04\/28\/continuing-the-story-of-early-dos-development\/#primaryimage","url":"https:\/\/opensource.microsoft.com\/blog\/wp-content\/uploads\/2026\/04\/86-DOS-Changelist.webp","contentUrl":"https:\/\/opensource.microsoft.com\/blog\/wp-content\/uploads\/2026\/04\/86-DOS-Changelist.webp","width":1260,"height":708,"caption":"Image of an 86-DOS Changelist."},{"@type":"BreadcrumbList","@id":"https:\/\/opensource.microsoft.com\/blog\/2026\/04\/28\/continuing-the-story-of-early-dos-development\/#breadcrumb","itemListElement":[{"@type":"ListItem","position":1,"name":"Home","item":"https:\/\/opensource.microsoft.com\/blog\/"},{"@type":"ListItem","position":2,"name":"Continuing the story of early DOS development"}]},{"@type":"WebSite","@id":"https:\/\/opensource.microsoft.com\/blog\/#website","url":"https:\/\/opensource.microsoft.com\/blog\/","name":"Microsoft Open Source Blog","description":"Open dialogue about openness at Microsoft \u2013 open source, standards, interoperability","publisher":{"@id":"https:\/\/opensource.microsoft.com\/blog\/#organization"},"potentialAction":[{"@type":"SearchAction","target":{"@type":"EntryPoint","urlTemplate":"https:\/\/opensource.microsoft.com\/blog\/?s={search_term_string}"},"query-input":{"@type":"PropertyValueSpecification","valueRequired":true,"valueName":"search_term_string"}}],"inLanguage":"en-US"},{"@type":"Organization","@id":"https:\/\/opensource.microsoft.com\/blog\/#organization","name":"Microsoft Open Source Blog","url":"https:\/\/opensource.microsoft.com\/blog\/","logo":{"@type":"ImageObject","inLanguage":"en-US","@id":"https:\/\/opensource.microsoft.com\/blog\/#\/schema\/logo\/image\/","url":"https:\/\/opensource.microsoft.com\/blog\/wp-content\/uploads\/2019\/08\/Microsoft-Logo.png","contentUrl":"https:\/\/opensource.microsoft.com\/blog\/wp-content\/uploads\/2019\/08\/Microsoft-Logo.png","width":259,"height":194,"caption":"Microsoft Open Source Blog"},"image":{"@id":"https:\/\/opensource.microsoft.com\/blog\/#\/schema\/logo\/image\/"},"sameAs":["https:\/\/x.com\/OpenAtMicrosoft"]}]}},"msxcm_display_generated_audio":false,"msxcm_animated_featured_image":null,"distributor_meta":false,"distributor_terms":false,"distributor_media":false,"distributor_original_site_name":"Microsoft Open Source Blog","distributor_original_site_url":"https:\/\/opensource.microsoft.com\/blog","push-errors":false,"_links":{"self":[{"href":"https:\/\/opensource.microsoft.com\/blog\/wp-json\/wp\/v2\/posts\/98477","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/opensource.microsoft.com\/blog\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/opensource.microsoft.com\/blog\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/opensource.microsoft.com\/blog\/wp-json\/wp\/v2\/users\/6277"}],"replies":[{"embeddable":true,"href":"https:\/\/opensource.microsoft.com\/blog\/wp-json\/wp\/v2\/comments?post=98477"}],"version-history":[{"count":9,"href":"https:\/\/opensource.microsoft.com\/blog\/wp-json\/wp\/v2\/posts\/98477\/revisions"}],"predecessor-version":[{"id":98491,"href":"https:\/\/opensource.microsoft.com\/blog\/wp-json\/wp\/v2\/posts\/98477\/revisions\/98491"}],"wp:featuredmedia":[{"embeddable":true,"href":"https:\/\/opensource.microsoft.com\/blog\/wp-json\/wp\/v2\/media\/98478"}],"wp:attachment":[{"href":"https:\/\/opensource.microsoft.com\/blog\/wp-json\/wp\/v2\/media?parent=98477"}],"wp:term":[{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/opensource.microsoft.com\/blog\/wp-json\/wp\/v2\/post_tag?post=98477"},{"taxonomy":"content-type","embeddable":true,"href":"https:\/\/opensource.microsoft.com\/blog\/wp-json\/wp\/v2\/content-type?post=98477"},{"taxonomy":"topic","embeddable":true,"href":"https:\/\/opensource.microsoft.com\/blog\/wp-json\/wp\/v2\/topic?post=98477"},{"taxonomy":"programming-languages","embeddable":true,"href":"https:\/\/opensource.microsoft.com\/blog\/wp-json\/wp\/v2\/programming-languages?post=98477"},{"taxonomy":"author","embeddable":true,"href":"https:\/\/opensource.microsoft.com\/blog\/wp-json\/wp\/v2\/coauthors?post=98477"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}