6502 Illegal Opcodes in the Siemens PC 100 Assembly Manual

The 6502’s “illegal” opcodes were of intense interest to home computer enthusiasts, and analyses were published in various magazines. But one would have never expected a company like Siemens to document illegal opcodes in a programming manual from 1980. The PC 100 Assembly Manual The Siemens PC 100 is basically a Rockwell AIM-65 single-board computer in a case, featuring a 6502 processor, integrated keyboard, LED display, and thermal printer, tailored for educational and development purposes with localized documentation and modified ROMs. Siemens’ German-language manuals were largely based on Rockwell’s originals, but shuffled the contents. Of particular interest is the assembly manual: Siemens Assembler-Handbuch Personal-Computer PC 100, Ausgabe 1980/1981 (124 pages, 17 MB) It consists of: “Special Instructions” The 6502 Reference has three extra pages at the end describing “Sonderbefehle” (“special instructions”) that were not in the original MOS/Rockwell 6502 reference tha ... Read full article.