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OPERATION
Copyright 1995, S
YS
I
RAN
Corp.
4-17
VME3U H/W REFERENCE
unchanged data values out on the network. This feature is a type of data filtering and can
be enabled without affecting node latency while improving network throughput. See
Figure 4-4, page 4-18.
Two bits in CSR0 control the operation of data filtering (see Section 5 for details of CSR
operation):
•
Bit 10 enables the data filtering during transmission to the SCRAMNet
+
memory and only for the address space above the first 4 K bytes.
•
Bit 11 enables the address space of the first 4 K bytes to be data-filtered in
conjunction with bit 10.
If bit 11 is OFF and bit 10 is ON, only the address space above 4 K bytes of
SCRAMNet
+
memory is data-filtered. If both bits 11 and 10 are ON, all SCRAMNet
+
memory is data-filtered. In either case, bit 10 must be ON for any data filtering to take
place on that node.
4.10.2 HIPRO Mode
WRITE
The SCRAMNet
+
network message is based on 32-bit longword data. If a host processor
is only capable of 8- or 16-bit data transactions, then the SCRAMNet
+
bandwidth is
quartered or halved, respectively. For each 32-bit data transaction from the host, two 16-
bit data transactions, or four 8-bit transactions will occur on the bus each requiring a
SCRAMNet
+
network WRITE.
The HIPRO mode was created to provide an efficient means to transmit two 16-bit data
transactions as one 32-bit network WRITE. The first of the two 16-bit WRITEs will be to
memory but will be prevented from going onto the network. The second 16-bit WRITE to
memory will trigger the WRITE of the 32-bit location to the network. Because the first
16-bit WRITE must be to the S memory, the Disable Host to Shared Memory
Write (CSR2, bit 8) cannot be used with HIPRO.
F
NOTE: The order of writing the shortwords or bytes into the longword boundary
does not matter. However, it is important that a HIPRO location does receive a
second shortword WRITE if a first shortword WRITE is initiated, or a total of 4-
byte WRITEs if a byte WRITE is initiated, to a HIPRO location. Otherwise, it is
possible to partially WRITE a 32-bit location causing the data to be lost and never
be transmitted.
The HIPRO mode is also effective for transmitting user defined 16-bit data items. Two
16-bit data items may be sent as one 32-bit data item if they are consecutive and lie
within the same 32-bit address boundary.
HIPRO mode is selected for those memory addresses which have ACR, bit 4 set.
HIPRO Enable (CSR2, bit 13) must also be set. A non-HIPRO location WRITE should
be used to synchronize the HIPRO flags.
Содержание SCRAMNet+ VME3U
Страница 1: ...SCRAMNet Network VME3U Hardware Reference Document No D T MR VME3U A 0 A2...
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Страница 52: ...OPERATION Copyright 1995 SYSIRAN Corp 4 26 VME3U H W REFERENCE Figure 4 10 Quad Switch...
Страница 72: ...CSR DESCRIPTIONS Copyright 1995 SYSIRAN Corp 5 18 VME3U H W REFERENCE This page intentionally left blank...
Страница 73: ...Copyright 1995 SYSIRAN Corp 6 1 VME3U H W REFERENCE 6 0 PHYSICAL FEATURES Figure 6 12 VME3U Layout...
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Страница 100: ...SPECIFICATIONS Copyright 1995 SYSIRAN Corp C 4 VME3U H W REFERENCE C 5 Fiber Optic Bypass Switch...
Страница 101: ...SPECIFICATIONS Copyright 1995 SYSIRAN Corp C 5 VME3U H W REFERENCE Figure C 2 Fiber Optic Bypass Switch...
Страница 102: ...SPECIFICATIONS Copyright 1995 SYSIRAN Corp C 6 VME3U H W REFERENCE Figure C 3 Housing Dimensions...
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Страница 115: ...E APPENDIX E CONFIGURATION AIDS TABLE OF CONTENTS...
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Страница 120: ...CONFIGURATION AID Copyright 1995 SYSIRAN Corp E 4 VME3U H W REFERENCE This page intentionally left blank...
Страница 121: ...F APPENDIX F ACRONYMS...
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Страница 124: ...ACRONYM Copyright 1995 SYSlRAN Corp F 2 VME3U H W REFERENCE This page intentionally left blank...
Страница 125: ...G APPENDIX G GLOSSARY...
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