Tag
real-mode
- Mar 19, 2026 Interrupt Vectors as the First Hardware Abstraction Layer The real-mode vector table turned firmware entry points into a stable calling convention, letting programs reach disks, video, and keyboards without knowing which adapter was installed. computing history
- Dec 3, 2025 Resident Programs and the Reentrancy Problem in DOS Terminate-and-stay-resident code hooks the timer or keyboard interrupt, but DOS itself is not reentrant, so a resident handler must either defer work or re-enter through a documented flag. computing history
- May 27, 2024 Segment Arithmetic and the One-Megabyte Wall How sixteen-bit segment registers produce a twenty-bit address, why the resulting space wraps at the top, and what the A20 gate and the high memory area cost. computing history
- Jan 7, 2024 The Reset Vector and the First Instruction Executed Why an x86 processor begins executing at 0xFFFFFFF0 in real mode, how that address reaches the firmware ROM, and what the sixteen bytes at the top of memory must contain. operating systems
- Dec 26, 2023 Why Boot Loaders Are Split Into Stages The 512-byte first sector, the real-mode address space that constrains where a second stage can live, and how chainloading hands control from firmware to a loader to a kernel. operating systems