On Fri, 12 Feb 2016 07:19:37 +0000, Martin Packer wrote: >But Unconditional being all 4 bits set was what I wanted elucidation on. >Perhaps I'm being thick, or perhaps it's a special case.
Condition code has two bits, giving it four possible values, 0, 1, 2, or 3. The mask bits in the conditional branch instructions have four bits, each bit corresponds to one of the four possible condition code settings. For example, if the first bit (bit 0) in the instruction mask is 1, it means take the branch if the condition code is zero. If the second mask bit (bit 1) is set, it means take the branch if the condition code is one. If all four bits are set, it means take the branch if the value of the condition code is 0, 1, 2, or 3. Since there are no other possible values, the branch is unconditional. -- Tom Marchant ---------------------------------------------------------------------- For IBM-MAIN subscribe / signoff / archive access instructions, send email to [email protected] with the message: INFO IBM-MAIN
