NonStop S-Series Server Description Manual (G06.24+)

TNS Data Formats and Number Representations
HP NonStop S-Series Server Description Manual—520331-003
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TNS Words and RISC Words
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completing the operation without rounding down the address
On the original TNS CISC processors (NonStop Cyclone and earlier), invalid odd
addresses always give the second behavior. On TNS/R processors, including the
NonStop S-series servers, the TNS and accelerated TNS execution modes give a mix
of these three behaviors for odd addresses. The TNS application programmer should
not count on any consistency, but should instead avoid forcing odd addresses into
extended pointers for nonbyte data.
Beginning with release version update G06.17, the operating system generates EMS
error events when invalid odd addresses are used in TNS or accelerated TNS modes.
Further, the TNS emulators can be configured to replace former round-down cases by
instruction-failure traps or by completion without round-down. This is controlled by new
Subsystem Control Facility (SCF) commands. The choice applies to all TNS
processes on that system. For details see the data misalignment information that is
provided in the Accelerator Manual, and in the SCF Reference Manual for the Kernel
Subsystem.
Endian Convention
In keeping with original conventions and big-endian design, bit numbering within an
object is left-to-right, the high-order, leftmost bit being bit 0. Manuals that specifically
describe the RISC chips generally assume the reverse. However, that difference is
only a documentary convention; no TNS or RISC instructions numerically designate bit
positions within a word.
Other Conventions
In this manual, a number surrounded by brackets is used to denote an individual
element (that is, byte, word, TNS doubleword, or TNS quadrupleword) in an array or
block of elements. For example, to indicate the fourth element in a word block
(beginning with element 0), the following notation is used:
WORD [3]
When referring to a block of words (or any elements), the first element is indicated by
the element number that is the lowest numerically; the last element has the highest
element number. The first and last elements are separated by a colon. For example, to
indicate the second through twentieth words in a block, the following notation is used:
WORD [1:19]
The following notation is used in this manual (and in the TAL language) to describe bit
fields:
WORD.<4:15>
This example defines a field within a word starting with bit 4 and extending through
bit 15. To indicate just bit 0, the following notation is used:
WORD.<0>