- 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.
- Moon Patrol (Wikipedia)
Moon Patrol (ムーンパトロール, Mūn Patorōru) is a 1982 arcade video game developed and released by Irem. It was licensed to Williams for distribution in North America. The player controls a Moon buggy which can jump over and shoot obstacles on a horizontally scrolling landscape as well as shoot aerial attackers. Designed by Takashi Nishiyama, Moon Patrol is often credited with the introduction of full parallax scrolling in side-scrolling games. Cabinet art for the Williams version was done by Larry Day. Most of the home ports were from Atari, Inc., sometimes under the Atarisoft label.