SDCC's z80 crt0 puts the reset vector at 0x0000 (jp init) and the init stub
(set SP, call _main) at an absolute .org 0x100. Passing `--code-loc 0x100`
relocated the _CODE segment on top of that init stub, so on reset the CPU
jumped into __clock/_exit (rst 0x08 then ret with a garbage stack) and
derailed into NOP land before ever reaching main — every Z80 C program ran
but drove nothing (z80-led-chaser-c compiled yet the LEDs never moved).
Verified via a standalone chip-WASM harness: with the flag the chaser does 0
LED writes; without it, it walks the bit (8 writes). Pairs with the z80-cpu
RAM map now covering 0x8000-0xFFFF so the crt0's SP=0 stack is real RAM.
Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>
e79368a04a