Category Archives: 8086/8088

Undocumented 8086 Opcodes, Part I

This is a guest post by Raúl Gutiérrez Sanz This multi-part document is about undocumented 8086 processor opcodes and their behavior. Most of the document will likely apply to the 8088 processor as well, but this has not been verified. … Continue reading

Posted in 8086/8088, Intel, Undocumented | 7 Comments

Undocumented 8086 Opcodes

A minor mystery recently surfaced while analyzing DOS boot sectors. DOS uses several criteria when deciding whether a boot sector contains a valid BPB, and one of the criteria is (oddly enough) checking whether the first two bytes of the … Continue reading

Posted in 8086/8088, Documentation, Intel, x86 | 57 Comments