- Star Tales combines Corvus and Crater on a single page
- 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.
- Star Tales - Corvus and Crater (ianridpath.com)
These two adjacent constellations are linked in a moral tale that goes back at least to the time of Eratosthenes in the third century BC. As told by Ovid in his Fasti, Apollo was about to make a sacrifice to Zeus and sent the crow to fetch water from a running spring. The crow flew off with a bowl in its claws until it came to a fig tree laden with unripe fruit. Ignoring its orders, the crow waited several days for the fruit to ripen, by which time Apollo had been forced to find a source of water for himself.