Jon Titus, Bugbooks, and the Mark 8

This document copyright Herbert R. Johnson 2014. updated Dec 31 2014.
Contact and email information can be found in this notice.

The Home page for all my Digital Research CP/M Web pages and information is at this link. The first CP/M systems and many others were S-100 bus based systems. To learn more about S-100check my S-100 home page.

Jonathan Titus has degrees in chemistry from the 1960's and 70's including PhD. work at Virginia Polytechnic Institute and State University. While there, he was part of a group of faculty and students including Dr. Chris Titus, Peter Rony, and David G. Larsen. Individually or in collaboration, they wrote many tutorial articles on TTL digital design, published in electronic trade publications of the early 1970's. Some of these were later published in book form as the "Bugbook" series starting in 1974. Some of the authors formed companies including the "Blacksburg Group Inc.", which produced additional books. The articles and books of the early 1970's taught and influenced many in the digital electronics industry as well as hobbyists, just as microprocessors became available.

In a 2009 email to me, Jon Titus said "The columns you mentioned appeared monthly in several publications: Radio-Electronics magazine (USA), Computer Design (USA), American Laboratory (USA), Electrical Lighting (South Africa), Elettronica Oggi (Italy), and perhaps one or two more. I still hear from people who used the Bugbooks or read our columns and they tell me how that information influenced their lives. That kind of communication means a lot."

In the early 70's, Jon worked with the early Intel microprocessors, and eventually developed a simple-to-build microcomputer around the Intel 8008. He developed the design into a construction article and in July 1974, Radio-Electronics published a front-page construction article on building his 8008 microcomputer called the Mark-8. Beyond the fact that the Mark-8 was a very early microprocessor-based computer kit, this article's appearance is credited as encouraging Radio-Electronics's magazine rival, Popular Electronics, to find a similar microcomputer construction project. What they found, and published a cover story about in January 1975, was the MITS Altair 8800.

Jon did not produce his products and kits in quantity. The project was intended by him to "show other hobbyists and experimenters they could have their own computer". In a 1999 interview by Doug Salot of the "Blinkenlights" Web site, he was quoted as follows: "I found my old tax forms and looked at the royalty amounts I received from Radio Electronics and from Techniques, the [New Jersey] company that produced the printed-circuit boards. It looks like Radio-Electronics sold about 7500 of the $5 [construction] booklets, which is far more that I would have remembered. About 400 sets of [$50] boards were sold."

Jon, or Jon and his Blacksburg colleagues, designed a number of related microcomputer projects. A "Mark 80" was designed and a book written to support it. A similar 8080 design was licensed to E&L Instruments as the MMD-1 or Mini Micro Designer.

Jon's career, from then forward into the 21st century, was and is in the electronics trade journals as a trade journal editor and author, and as a digital consultant. He continued to be an author or co-author of many books on digital design. And, he continues to be considerate to newcomers to what was called "microcomputing", even as he writes about the latest microprocessor development kits and products.

An article relevant to CP/M history was Jon's September 15 2001 editorial on IBM-PC history on its 20th year. Check his article at this link to the Test & Measurement World's Web site.

A Web site about Jon Titus

In late June 2008, I stumbled across a Web site on Jonathan Titus and his Mark-8 8008 computer. It's apparently a 2007 Web site for student participants in the 2006 IEEE Computer Society student competition, at Florida Gulf Coast University. The student team which produced the Web site was mentored by Dr. Janusz Zalewski at FGCU, who maintains the Web site on the Computer Science department's server. (As of late June 2009, that server was off-line; Dr Zalewski is working to restore it.) Jon Titus gave them an interview about his Mark-8 development; and they have archived an earlier interview he gave on the subject. A few quotes above are exerpted from material and interview from this site.

The IEEE Computer Society Web Programming Competition (referred to as CHC) for 2006 was monitored by Dr. Alan Clements, a computing professor and computer historian at the University of Teesside in the UK. He has some notes on microcomputer history on his Web site, and a book on microcomputing history in progress as of 2008.

Another Web site about Jon Titus

In 2012 I came across another Web site, which rescued yet ANOTHER set of Web page's about Jon Titus and his early work at Blacksburg. Christian Liendo describes how he recovered in 2010, previous work by Andrew Davie and Jon Titus which described the development of the Mark-8. His permitted copy of Titus' history around the Mark-8 are linked here.

About "Blacksburg Group" and "Bugbooks"

A number of companies were formed in association with the people mentioned above from Virginia Polytechnic, and others became involved over time. A series of "Blacksburg" or "Bugbook" books, or books with bug images, were published. There's different descriptions of the specifics, which at this time I leave to those involved to represent.

Peter Rony has two Web sites which discuss his views: and My apologies to him, for omitting his name in an early version of this Web page. His sites describe some early work and companies associated with that work, and he asserts how ownership of some of that work and intellectual property was resolved.

David Larsen has a Web site at That site identifies many people who participated in various books of the "Blacksburg Group", and catalogs those books.

David Larson's museum, the Mark-8, and one builder's story

In the last several years, David Larsen has developed a computer museum and a number of supporting Web sites and blogs. On, he's accumulated a number of discussions, audio and video recordings, and images and other content about his museum in Floyd, Virginia. Particular to Jon Titus's Mark-8, he has a number of those computers, and some information about their builders.

One Mark-8 builder was George Overfelt, who like many Mark-8 owners built it as he followed the Radio-Electronic articles about it. David obtained that Mark-8, and loaned it to another museum (MARCH in New Jersey) for display and restoration, as described on David's blog page. There's also an audio conversation between David and George, about how George came to make the Mark-8 and what he did with it, and after it. The conversation was referenced to me, by Evan Koblentz of MARCH in December 2014. The conversation impressed me as a good respresentation of mid-1970's microcomputing. So I transscribed the conversation and, with David's permission, here's the story of George Overfelt's construction and use of a Mark-8 in 1974.

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Herb Johnson
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