- Oyster fishing and logging were the dominant industries in the Chuckanut area from the late nineteenth to early twentieth centuries. The forest lands of Blanchard Mountain became state trust lands in the 1920s and 1930s, giving the forest a needed respite. Much of the forest on Blanchard is second-growth; logging artifacts can be seen on the trail, and giant stumps inspire imagination about the towering cathedral forests that blanketed the mountain prior to logging.
- Silicon reverse-engineering: the Intel 8086 processor’s flag circuitry (righto.com)
Status flags are a key part of most processors, indicating if an arithmetic result is negative, zero, or has a carry, for instance. In this post, I take a close look at the flag circuitry in the Intel 8086 processor (1978), the chip that launched the PC revolution.1 Looking at the silicon die of the 8086 reveals how its flags are implemented. The 8086’s flag circuitry is surprisingly complicated, full of corner cases and special handling. Moreover, I found an undocumented zero register that is used by the microcode.