Blog
Welcome to the Blog.
IRQ Maps and the Politics of Slots
2026-02-22
Anyone who built or maintained DOS-era PCs remembers that hardware conflicts were not rare edge cases; they were normal engineering terrain. IRQ lines, DMA channels, and I/O addresses had to be negotiated manually, and each new card could destabilize a previously stable system. This was less like plug-and-play and more like coalition politics in a fragile parliament.
The core constraint was scarcity. Popular sound cards wanted IRQ 5 or 7. Network cards often preferred 10 or 11 on later boards but collided with other devices on mixed systems. Serial ports claimed fixed ranges by convention. Printer ports occupied addresses and IRQs that software still expected. These were not abstract settings. They were finite shared resources, and two devices claiming the same line could produce failures that looked random until you mapped the whole system. ... continue
Turbo Pascal Units
2026-02-22
Most people first meet Turbo Pascal units as “how to avoid copy-pasting procedures.” That is true and incomplete. In real projects, units are architecture boundaries. They define what the rest of the system is allowed to know, hide what can change, and make refactoring survivable under pressure.
In constrained DOS projects, this was not academic design purity. It was the difference between shipping and debugging forever. ... continue
Overlay Lab: Build and Debug OVR
2026-02-22
This tutorial is intentionally practical. You will build a small Turbo Pascal program with one resident path and one overlayed path, then test deployment and failure behavior.
If your install names/options differ, keep the process and adapt the exact menu or command names. ... continue
Turbo Pascal History
2026-02-22
People often tell Turbo Pascal history as a sequence of versions and release dates. That timeline matters, but it misses why the tool changed habits so deeply. The real story is tooling ergonomics under constraints: compile speed, predictable output, integrated editing, and a workflow that kept intention intact from keystroke to executable.
In other words, Turbo Pascal was not only a language product. It was a decision system. ... continue
BGI Lab: Drivers and Diagnostics
2026-02-22
This tutorial gives you a practical BGI workflow that survives deployment:
TP5 baseline reminder: ... continue