Foundational Computing
Assembly, C, COBOL, Pick, RPG, and midrange systems — when you had to understand the hardware, memory, and business process at once.
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Technology Across Generations
A career across generations of computing.
Mark Kiessling's career did not begin with the web, .NET, cloud computing, or artificial intelligence. It began when computing demanded a deep understanding of hardware, memory, communications, operating systems, data structures, and the limits of the machine itself. Across approximately forty-seven years he has worked through many generations of technology — from early business systems, assembly language, COBOL, Pick, RPG, DOS, early Windows, Unix, and legacy network protocols, through relational databases, client-server architecture, internet systems, modern web platforms, cloud infrastructure, game engines, automation, and AI.
The value is not the length of the list. It is understanding why systems evolved, which principles survived, why old mistakes return under new names, and how a decision in one part of an organization affects everything connected to it.
The Arc
Six broad eras, one continuous career.
Approximate eras, not hard dates — many overlapped. C# and .NET belong to the most recent chapter, not the beginning.
Desktop & Business Systems
DOS and early Windows, FoxPro, PowerBuilder, Visual Basic, and desktop databases powering real business operations.
Client-Server & Databases
Relational platforms, networking, and multi-tier applications — Sybase, Oracle, SQL Server, and enterprise data design.
Internet & Web
ISP operations, hosting, DNS and email, classic ASP through ASP.NET, and the full evolution of web application development.
Enterprise & Executive
Software and enterprise architecture, security, project and department leadership, and CTO / CIO responsibility.
Modern & AI
Current C# and .NET, cloud, automation, and practical, governed use of artificial intelligence — the latest chapter, not the whole story.
By Discipline
The depth behind the arc.
Select any area to expand it. Each notes what the experience actually means — not just what it was called.
Foundational Computing
Where developers had to understand the whole machine
Early in Mark's career, a developer routinely had to understand the hardware, the operating environment, memory limits, storage, communications, and the business process at the same time. That discipline — making systems work within real constraints — still shapes how he evaluates architecture today.
These are technologies Mark has programmed with, supported, evaluated, or worked around over the years — not a claim of current, equal mastery of each.
Operating System Generations
Compatibility, migration, and why legacy stays business-critical
Experience across many operating-system families lets Mark reason clearly about compatibility, migration, legacy dependencies, platform transitions, and the real reasons older systems often remain business-critical long after they are declared obsolete.
DOS & early Windows Windows client (NT line) Windows Server Unix, Linux & midrangeNetworking and Communications
More than configuring a modern router
Mark's networking experience spans building, operating, troubleshooting, and migrating systems across several generations of network technology and internet infrastructure — from legacy LAN protocols to ISP operations and communications hardware.
That story starts earlier than most. His first step beyond his own programs was the bulletin-board era — running Spitfire BBS over dial-up modems that climbed from 2400 baud to 9600 and eventually 56K — which led into the pre-public internet and ARPANET, the military and university network that became the internet. Searches then relied on early tools like Archie and Veronica, passed from machine to machine, where a single query could take a week to come back.
Bulletin boards & the early internet Protocols & services Hardware & vendorsDatabases and Data Systems
From desktop databases to enterprise relational platforms
Data is central to Mark's value. He has worked with data from desktop database systems through enterprise relational platforms and distributed internet applications — design, performance, reliability, and recovery, not one product in isolation.
Platforms Design & engineeringProgramming Language History
Classified honestly — not everything is “current expert”
The languages below span the chronology of Mark's work. They are grouped by how the experience should be read — because honest classification is part of credibility.
Foundational & historical experience Long-term production experience Modern working technologies Specialized or project-basedSoftware Architecture & Application Types
Whole systems, not just languages
Mark has built complete systems across the stack — understanding how the pieces fit is the point, not any single language.
Tools & Development Environments
The changing workbench of a long career
A working history across many business and development environments — listed as part of the story, not inflated into technical accomplishments.
Graphics, Media & Game Technology
From early ray tracing to modern engines
A distinct thread runs from early three-dimensional graphics through modern game engines. This work connects directly to Mark's engagements with XOX Chicago, Bally Midway, BioWare, Sony Online Entertainment, and his independent game-server and launcher projects — described in The Playbook. No sole-authorship of famous titles is claimed.
Techniques Tools & platformsInternet & Web Evolution
Infrastructure and applications, not just page design
Mark's internet work spans infrastructure, application design, databases, hosting, communications, security, and business integration — across the full evolution of web development, not only the visible page.
Security & Operational Experience
Access, recovery, continuity, and disciplined testing
Operational judgment built from running real systems — not certifications on paper. (No specific certifications or compliance claims are made here.)
Management & Executive Experience
Why he can speak to programmers and boards alike
Technical breadth is only half the story. Mark can communicate with programmers, database administrators, infrastructure teams, vendors, managers, investors, and executives because he has done the work at each of those levels.
Reported scope across engagements: budgets from roughly ten thousand dollars up to about 12.5 million dollars; teams from roughly five people up to about 455; cost reductions reported in the range of about ten to sixty percent where applicable. (Exact figures per engagement are confirmed with Mark before use in a specific proposal.)
Modern Technology
The latest chapter — not the beginning
Current, active work — shown last on purpose. It is the most recent chapter of a long career, not its starting point.
See Mark's AI Systems for the applied work — a voice assistant, mobile robotics, and a supervised AI production team.
A Signature Story
You get what you pay for.
Early in the 1990s, Mark was called to a Chicago title company on a Saturday. Several floors of computers were dead — hundreds of machines per floor, an office full of people billing by the hour, and a business losing money by the minute. He took the two-hour train downtown, looked closely at the machines, and asked for the building manager. Together they went to the sub-basement, where Mark found the right breaker box and a single tripped breaker, and threw it. Every computer came back on.
He handed over a bill for ten thousand dollars — real money in the early nineties. It was refused on the spot: you didn't do anything. So he offered to itemize it.
$10 — for his time.
$9,990 — for knowing which switch to throw.
$9,990 — for knowing which switch to throw.
That is the whole idea behind this practice. You are not paying for the hour. You are paying for the judgment that finds the one thing that matters — quickly — before it costs you far more.
Mark's value is not that he remembers old software. It is that he understands how modern systems were built, which old problems they solved, which old problems they recreated, and what an organization risks when it replaces knowledge with fashion.
A consultant who has only seen current technology can recommend what is popular. A consultant who has watched the industry evolve can explain what will survive.
Technology Matrix
How to read the experience.
The same technologies, sorted honestly by how Mark works with them today. Placement in “Current and active” reflects present work, not everything ever touched.
Current and active
Used in Mark's present work.
Extensive production experience
Deep, sustained use over years.
Historical production experience
Shipped real systems in earlier eras.
Architectural & advisory knowledge
Evaluated and guided at the decision level.
Older technology is kept here on purpose. The historical range is part of Mark's credibility — not a claim of current expert-level mastery of every item. Where a specific engagement depends on it, Mark is candid about what he works with today versus what he worked with in an earlier era.
From the Field
Start the Conversation
The perspective to tell what will survive from what is merely popular.
If you are weighing a migration, a modernization, a due-diligence review, or an AI decision, that long view is available now.