Our Story

Our Story

ColeSoft Marketing produces superior debugging products for software engineers and support staff working on IBM Mainframes.

At the core of ColeSoft Marketing is David Cole, who has 40 years of experience in mainframe systems programming and development starting with MFT and running through MVS and today's z/OS systems. Throughout his career, Dave has had the opportunity to work on nearly every element of the z/OS operating system and has earned a reputation as an authority in his field. He is the author and lead developer of the company's core product, the source level assembler debugger z/XDC, which first came to market as "DeBugging Controller" or DBC in 1980.

During his employment at Yale University, Dave first conceived of z/XDC as it is today – a powerful development tool for Assembler Language programmers. The product's design and coding began around 1978. The first predecessors to z/XDC were simple trapping and zapping utilities that evolved along with Dave's career in systems programming. Early on, DCB became available to selected users by word of mouth. Several prominent software development houses were among the product's early customers. The needs of those sophisticated users helped drive the evolution of the product from its inception.

Dave's son Calin was born in 1981. Shortly afterwards, Dave left Yale and he and his family moved from New Haven, Connecticut, to Afton, Virginia. Dave took a job in Washington, DC, and for several years commuted to DC and back every week.

In 1984, Dave completed a major overhaul of DBC, expanding its scope from 24-bit to 31-bit systems, and re-christened the product XDC, for Extended Debugging Controller. Then, in 1988, Dave bought out the rights to XDC from Yale and formally started Cole Software, now called ColeSoft Marketing. Dave had known Bob Shimizu while working in DC, and brought Bob on board to help with marketing and sales for XDC.

Cole Software operated out of Dave's home in Afton for several years, until 1992 when Dave rented the farmhouse next door and established a separate office. Then, in the late 1990s, ColeSoft really began to grow. In 1995 and 1997, Wendie Wyant and Tamara Critzer joined the team on the administrative side, and in 1998 Frank Chu was hired as an additional programmer. This core group of people has been integral to ColeSoft's success.

Colesoft Marketing

In 2010, Michael Lewis was brought on as a full time development programmer. Mike had already contributed greatly to the product throughout the years, building XDC's terminal full screen support and cross domain facility on a contract basis.

In 2013, Dave's son Calin Cole formally joined the company as Vice President, and ColeSoft moved home base from its farmhouse in Afton to downtown Charlottesville, Virginia. The office is just blocks from the city's epicenter, a historic and beautiful tree-lined pedestrian mall with dozens of shops and restaurants. It no longer has a full kitchen, but that doesn't stop Frank from whipping up some impressive meals on occasion.


ColeSoft believes that the existence of z/XDC has helped contribute to the continued usefulness of the Assembler Language as a modern program development tool. Just as MVS/SP evolved over the years to become z/OS, z/XDC has evolved from the original DeBugging Controller into a full-featured, powerful development tool.

ColeSoft's greatest strengths are strong support for our user community and continued refinement of our products from a team of dedicated programmers. Our users also have a great deal to do with ColeSoft's and z/XDC's future direction, and their needs and feedback contribute directly to our products' development.

z/XDC's user community is small but represents some of the best minds in the software industry and Assembler community. Our users are among the industry's foremost software development houses and Fortune 500 companies. To learn more about ColeSoft's core product and find out if z/XDC can help you or your team, please take a look at our z/XDC product page or contact This email address is being protected from spambots. You need JavaScript enabled to view it. for more information.

Charlottesville, VA