COBOL 103: The Missing Dot Notation and the Genius of Data Levels
Part 3: Why COBOL doesn't use dot notation, and how its clunky-looking hierarchical data levels are actually a masterclass in bare-metal memory efficiency.
COBOL & Z Server
For the love of bare metal machines.
May 2026
COBOL 104: The Complete Zero-Bloat To-Do Application
The grand finale of our COBOL Todo List. Here is the complete, copy-pasteable source code for a full CRUD To-Do application built entirely on the bare metal with sequential files.
COBOL 103: The Cassette Tape Pattern (Deleting and Editing Data on the Metal)
Part 3: How do you delete a record from a sequential file without a database? You use the Cassette Tape Pattern. Let's finish our COBOL To-Do app with full CRUD capabilities.
COBOL 102: Building a To-Do List and Escaping the Modern Web
Part 2: Every JavaScript framework tutorial builds a To-Do app using 400MB of dependencies. Let's build one in COBOL using bare-metal sequential files and zero bloat.
COBOL 101: Hello World, Taxes, and Why Mainframes Hate Prompts
Part 1 of our COBOL series. Learn how to write and compile your first COBOL programs locally using GnuCOBOL, and understand the fundamental difference between interactive apps and Mainframe JCL batch processing.
First Steps on the Mainframe
What it feels like to finally sit in front of a z/OS system and realise that most of the modern world runs on hardware nobody talks about.
The Predictable Beauty of COBOL and JCL
A dive into COBOL, fixed-point math, and JCL.