She knew LDS —Load Pointer Using DS. A relic from the segmented memory model of the 16-bit era, when pointers were 32-bit monsters: a 16-bit segment and a 16-bit offset. On her 32-bit 386, it still worked—mostly. But it was a time bomb.
And somewhere in a museum, a 386 motherboard smiled, its LDS instruction still perfectly capable of crashing any program that dared to wake it. x86 lds
She couldn’t just remove the LDS . The entire linked list traversal depended on far pointers. But she could replace it. She knew LDS —Load Pointer Using DS
“It poisoned its own segment register,” Eleanor whispered. “Like a snake biting its tail.” But it was a time bomb
The offending line looked innocent:
The code was a fossil, written in a hybrid of C and inline assembly by a geophysicist who had long since retired to a cabin without electricity. The error was a General Protection Fault (GPF)—the 386’s way of screaming, “You touched memory you don’t own.”
She wrote a small C helper using memcpy to safely read the 32-bit value into a local unsigned long , then manually set DS and BX via __asm —but with interrupts disabled via _disable() . Clunky, but safe.