halfwords in length
in storage on a halfword boundary. Each
instruction is 1n one of eight basic
formats: RR, RRE, RX, RS, SI,
and SS, with two variations of
the figure "Basic Instruction Formats.")
Some instructions contain fields that
vary slightly from the basic format, and
in some instructions the operation
performed does not follow the general
rules stated in this section. All of
these exceptions are explicitly identi
fied in the individual instruction
descriptions.
Those instruction formats which
the vector facility are described in the
publication IBM
The format names indicate, in general
terms, the classes of operands which
participate
operation.
RRE denotes
operation having an extended
op-code field.
RX denotes a register-and-indexed
storage operation.
RS denotes
register-and-storage
operation.
implied operand and storage.
operation.
operation having an extended
op-code field.
RR Format
o
RRE Format
o 16 24
RX Format
o 8 12 16
RS Format
o 8 12 16
SI Format
0
_
p
Basic Instruction Formats
The first byte or, in the RRE,
of an
For
all
instruction contain the op code.
some instructions in the
or
ignored.
byte of the op
and format of the instruction,