GLOSSARY
Copyright 2007
Glossary 3
S SC150e HARDWARE REFERENCE
interrupter
------------------------A functional module that generates an interrupt request on the priority
interrupt bus and then provides states/ID information when the interrupt
handler requests it.
interrupt handler
----------------A functional module that detects interrupt requests generated by
interrupters and responds to those requests by asking for status/ID
information.
I/O space
---------------------------The regions of host processor physical address space that contain the
configuration registers, device control, states registers and data registers.
These regions are physically noncontiguous.
ISR
----------------------------------interrupt service routine. A routine executed when a device interrupt
occurs.
latched
-----------------------------Data is electrically stored in a circuit until it is needed. A method of
coordinating two synchronous events.
locking a page in memory
------Making a page ineligible for either paging or swapping. A page stays
locked in physical memory until the operating system specifically
unlocks it.
longword
---------------------------Four bytes (32 bits) of data.
loopback
---------------------------A method of transmitting to the same node’s receivers for testing
purposes. Applies to both fiber optic and wire media. Also, a test that
loops the outgoing signal back to its source.
master
------------------------------A functional module that initiates DTB cycles to transfer data between
itself and a slave module.
message packet
-------------------See packet.
native message
--------------------A message that is received by the node of origin.
node latency
-----------------------The time delay at a node before a foreign message can be retransmitted.
packet
------------------------------A message that travels on the network. The minimum packet consists of
81 bits and 1 start bit. The packet includes five fields: Source ID (8 bits),
Age (8 bits), Control (3 bits), Data Address (21 bits), Data (32 bits), and
9 parity bits; one for every 8 bits.
physical address
------------------The address used by hardware to identify a location in physical memory
or on directly-addressable secondary storage devices (such as disks). A
physical memory address consists of a page-frame number and the
number of a byte within the page.
PIO
---------------------------------programmed I/O transfer. An I/O transfer, primarily conducted by a
driver program, that requires processor intervention after each byte or
word is transferred. Contrast with Direct Memory Access (DMA)
transfer.
PLATINUM
----------------------A protocol where messages are transmitted as fast as the system will
allow with error correction enabled.
P
---------------------Also platinum plus.
A variable-length message packet size enhancement
for the platinum protocol. Maximum packet size may be set to either 256
bytes or 1024 bytes plus a 46-bit header.
priority interrupt bus
-----------One of the four buses provided by the backplane. The priority interrupt
bus allows interrupter modules to send interrupt requests to interrupt
handler modules, and interrupt handler modules to acknowledge these
interrupt requests.
Summary of Contents for SCRAMNet+ SC150e
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