On Tue, 12 Jul 2016 14:19:26 -0700, Charles Mills wrote: ><pedantry> > >The op code is ... just a binary byte in any event, not hex.
In some cases there are more bits than the first byte of an instruction that are part of the opcode. Opcodes can be 8, 12, or 16 bits, depending on the instruction. The first 8 bits of the opcode are always in bits 0-7 of the instruction. Bits 8-11 of a 12-bit opcode are always in bits 12-15, and bits 8-15 of a 16-bit opcode are either in bits 8-15 or bits 40-47, depending on the value in the first 8 bits. For example, if the byte in bits 0-7 contains X'E3', the remaining bits of the opcode are in bits 40-47. ></pedantry> -- Tom Marchant ---------------------------------------------------------------------- For IBM-MAIN subscribe / signoff / archive access instructions, send email to [email protected] with the message: INFO IBM-MAIN
