On Fri, 2024-11-01 at 11:01 -0700, David Barto via cctalk wrote: > > > The 6502 had a HCF (halt and catch fire) undocumented > > > instruction. > > > I forget the opcode and if you knew what you were doing you could > > > get the instruction executed on the chip using any assembler.
Early in 1965 Caltech installed one of only a few 360/63 computers. After they installed it, they discovered that the default instruction when it started up was HCF. It was replaced with a 360/67.
