HLASM Language Reference

Input/Output Operations
For further details, see “Control Instructions” in the applicable Principles of
Operation manual.
Input/Output Operations
Use the input/output instructions (instead of the IBM-supplied system macro
instructions) when you want to control your input and output operations more
closely.
The input or output instructions let you identify the channel or the device on which
the input or output operation is to be done. For information about how and when
you can use these instructions, see the applicable system manual.
For more information, see “Input/Output Operations” in the applicable Principles of
Operation manual and the applicable system manuals.
Branching with Extended Mnemonic Codes
Branch instructions let you specify an extended mnemonic code for the condition on
which a branch is to occur. Thus, you avoid having to specify the mask value, that
represents the condition code, required by the BC, BCR, and BRC machine
instructions. The assembler translates the extended mnemonic code into the mask
value, and then assembles it into the object code of the BC, BCR, or BRC machine
instruction.
| The extended branch mnemonics for the BC instruction require a base register; the
| extended mnemonics for the BCR and BRC instructions do not. The extended
| mnemonics for the BRC instruction begin with the letter “J,” and are sometimes
| called “Jump” instructions, as indicated in Figure 22.
The extended mnemonic codes are given in Figure 22 on page 81. They can be
used as operation codes for branching instructions, replacing the BC, BCR, and
BRC machine instruction codes (see ▌1▐ in Figure 22). Note that the first operand
(see ▌2▐ in Figure 22) of the BC, BCR, and BRC instructions must not be present
in the operand field (see ▌3▐ in Figure 22) of the extended mnemonic branching
instructions.
80 HLASM V1R5 Language Reference