Extended Memory Interconnect - Revision history

Jnc: More accurate new category

2024-05-07T23:43:19Z

More accurate new category

Jnc: XMI bus systems are tightly-coupled multi-processors

2023-03-20T11:44:04Z

XMI bus systems are tightly-coupled multi-processors

Jnc: better img loc

2023-03-19T20:04:19Z

better img loc

Jnc: Copyedit

2023-03-19T06:19:08Z

Copyedit

Jnc: Improve description

2023-03-18T12:00:39Z

Improve description

Jnc: +cat, for finding

2023-03-17T11:44:46Z

+cat, for finding

Jnc: /* External links */ +manual

2022-07-17T19:53:37Z

‎External links: +manual

Vaxorcist: Added some details

2022-07-17T11:35:47Z

Added some details

Vaxorcist: Added some more details

2022-07-17T11:10:11Z

Added some more details

Vaxorcist: New page

2022-07-17T10:02:55Z

New page

New page

The Extended Memory Interconnect (acronym: XMI) was a bus introduced with the VAX 6000 series of DEC computers to cope with increased requirements, e.g bandwidth.

The XMI bus started with the "+5V '''XMI-1'''" version which was developed to the "+3.3V '''XMI-2'''" version lateron.

{{stub}}

[[Category: DEC Buses]]
[[Category: XMI]]

@@ Line 63: / Line 63: @@
 * [http://www.vaxhaven.com/images/f/fc/EK-650EB-UP-002.pdf EK-650EB-UP-002 VAX 6000 XMI Conversion Manual]
-[[Category: DEC Buses]]
+[[Category: VAX Buses]]
 [[Category: XMI]]

@@ Line 1: / Line 1: @@
 [[File:VAX 6200 Four-Processor System Block Diagram.png|thumb|400px|rightt|A four-processor VAX 6200 system built around an XMI bus]]
-The '''Extended Memory Interconnect''' (usually given as the acronym: '''XMI''') was a [[bus]] introduced with the [[VAX 6000 series]], and also used in other later [[Digital Equipment Corporation|DEC]] [[VAX]] computers, to cope with increased requirements, e.g bandwidth. It supports multiple processors, multiple memory modules, and multiple I/O adapters.
+The '''Extended Memory Interconnect''' (usually given as the acronym: '''XMI''') was a [[bus]] introduced with the [[VAX 6000 series]], and also used in other later [[Digital Equipment Corporation|DEC]] [[VAX]] computers, to cope with increased requirements, e.g bandwidth.
-The XMI is the primary interconnect for the [[VAX 6000 Model 200|VAX 6200]] system (as shown to the side).:
+It supports multiple processors, multiple [[main memory]] memory modules, and multiple I/O adapters; the overall system built around an XMI bus thus forms a tightly-coupled [[multi-processor]]. The bus has special capabilities to support the shared access to memory required by such a system.
 ==Overview==

@@ Line 1: / Line 1: @@
 The '''Extended Memory Interconnect''' (usually given as the acronym: '''XMI''') was a [[bus]] introduced with the [[VAX 6000 series]], and also used in other later [[Digital Equipment Corporation|DEC]] [[VAX]] computers, to cope with increased requirements, e.g bandwidth. It supports multiple processors, multiple memory modules, and multiple I/O adapters.
 ==Overview==
@@ Line 13: / Line 17: @@
 It is also 'pended', which means that an operation can be left in an incomplete state, to allow other entities to use the bus, before resuming, and finishing. Several transactions can thus be in progress at any time, rather than forcing later operations to wait for the completion of an earlier operation before they can begin; this allows highly efficient use of the bus bandwidth.
 The XMI supports:

@@ Line 1: / Line 1: @@
-The '''Extended Memory Interconnect''' (usually given as the acronym: '''XMI''') was a [[bus]] introduced with the [[VAX 6000 series]], and also used in later [[Digital Equipment Corporation|DEC]] [[VAX]] computers, to cope with increased requirements, e.g bandwidth.
+The '''Extended Memory Interconnect''' (usually given as the acronym: '''XMI''') was a [[bus]] introduced with the [[VAX 6000 series]], and also used in other later [[Digital Equipment Corporation|DEC]] [[VAX]] computers, to cope with increased requirements, e.g bandwidth. It supports multiple processors, multiple memory modules, and multiple I/O adapters.
 ==Overview==
-The XMI bus supports multiple processors, multiple memory modules, and multiple I/O adapters. It consists of:
+The constituent elements of the XMI bus are:
-* the electrical environment of the XMI bus,
+* the [[analog]] electrical element of the bus,
 * the [[protocol]] observed by a node on the bus,
 * the [[backplane]], and
 * the [[logic]] used to implement the protocol.
-The XMI is limited length, [[synchronous]], and has centralized [[arbitration]] (individual [[bus grant line]]s run from the arbitrator to each slot in the backplane). Arbitration and data transfers use logically separate divisions of the bus, so they can occur in parallel.
+The XMI is of limited length, is [[synchronous]], and has centralized [[arbitration]] (individual [[bus grant line]]s run from the [[arbitrator]] to each slot in the backplane). Arbitration and data transfers use logically separate divisions of the bus, so they can occur in parallel.
-It is also 'pended', which means that an operation can be left in an incomplete state, to allow other entities to use the bus. Several transactions can thus be in progress at any time, rather than forcing later operations to wait for the completion of an earlier operation before they can begin; this allows highly efficient use of the bus bandwidth.
+It is also 'pended', which means that an operation can be left in an incomplete state, to allow other entities to use the bus, before resuming, and finishing. Several transactions can thus be in progress at any time, rather than forcing later operations to wait for the completion of an earlier operation before they can begin; this allows highly efficient use of the bus bandwidth.
-The XMI is the primary interconnect for the [[VAX 6000 Model 200|VAX 6200]] system.
+The XMI is the primary interconnect for the [[VAX 6000 Model 200|VAX 6200]] system:
 [[File:VAX 6200 Four-Processor System Block Diagram.png|thumb|400px|left|A four-processor VAX 6200 system]]
@@ Line 27: / Line 27: @@
 The longword operations implement byte and word modes required by certain I/O devices.
-The XMI has a 64 ns bus cycle. It has a bandwidth of 100 Mbytes per second; however, the usable bandwidth depends on transaction length:
+It has a 64 ns bus cycle, and a bandwidth of 100 Mbytes per second; however, the usable bandwidth depends on transaction length:
 {| class="wikitable"
@@ Line 49: / Line 49: @@
 |}
-==XMI Versions==
+==XMI versions==
-The XMI bus started with the "+5V '''XMI-1'''" version which was developed to the "+3.3V '''XMI-2'''" version later on.
+The XMI bus started with the "+5V '''XMI-1'''" version, which was developed to the "+3.3V '''XMI-2'''" version later.
-There was an upgrade kit option H9657-CU that takes a VAX 6000 Model 200, 300, or 400 system with an XMI-1 power system and upgrades it to a VAX 6000 Model 500 with an XMI-2 power system. The upgrade adds +3.3 volt power, an XMI-2 backplane preassembled with bus bars and cables, and an H7206-B power and logic unit.
+There was an upgrade kit, option H9657-CU, which takes a VAX 6000 Model 200, 300, or 400 system with an XMI-1 power system, and upgrades it to a VAX 6000 Model 500, with an XMI-2 power system. The upgrade adds +3.3 volt power, an XMI-2 backplane pre-assembled with bus bars and cables, and an H7206-B power and logic unit.
 {{semi-stub}}
@@ Line 59: / Line 59: @@
 ==External links==
-* [http://www.bitsavers.org/pdf/dec/vax/6200/EK-620AA-TM-001_Tech_May88.pdf VAX 6200 Technical User's Guide] (EK-620AA-TM-001) - the XMI is covered in Chapter 2, pp. 37-91 of the PDF
+* [http://www.bitsavers.org/pdf/dec/vax/6200/EK-620AA-TM-001_Tech_May88.pdf VAX 6200 Technical User's Guide] (EK-620AA-TM-001) - the XMI is covered in Chapter 2 (pp. 37-91 of the PDF)
 * [http://www.vaxhaven.com/images/f/fc/EK-650EB-UP-002.pdf EK-650EB-UP-002 VAX 6000 XMI Conversion Manual]

@@ Line 1: / Line 1: @@
-The '''Extended Memory Interconnect''' (usually given as the acronym: '''XMI''') was a [[bus]] introduced with the [[VAX 6000 series]] of [[Digital Equipment Corporation|DEC]] computers to cope with increased requirements, e.g bandwidth.
+The '''Extended Memory Interconnect''' (usually given as the acronym: '''XMI''') was a [[bus]] introduced with the [[VAX 6000 series]], and also used in later [[Digital Equipment Corporation|DEC]] [[VAX]] computers, to cope with increased requirements, e.g bandwidth.
-== XMI Overview ==
+==Overview==
-Figure 2-1 shows a four-processor VAX 6200 system.
+The XMI bus supports multiple processors, multiple memory modules, and multiple I/O adapters. It consists of:
-[[File:VAX 6200 Four-Processor System Block Diagram.png]]
+* the electrical environment of the XMI bus,
-The XMI consists of the electrical environment of the XMI bus, the protocol observed by a node on the bus, the backplane, and the logic used to implement the protocol.
+The XMI is limited length, [[synchronous]], and has centralized [[arbitration]] (individual [[bus grant line]]s run from the arbitrator to each slot in the backplane). Arbitration and data transfers use logically separate divisions of the bus, so they can occur in parallel.
-The XMI bus is limited length, pended, and synchronous with centralized arbitration. Several transactions can be in progress at a given time, allowing highly efficient use of the bus bandwidth. Arbitration and data transfers can occur simultaneously.
+It is also 'pended', which means that an operation can be left in an incomplete state, to allow other entities to use the bus. Several transactions can thus be in progress at any time, rather than forcing later operations to wait for the completion of an earlier operation before they can begin; this allows highly efficient use of the bus bandwidth.
 * Quadword-, octaword-, and hexword-length reads to memory
 * Quadword- and octaword-length memory writes
@@ Line 19: / Line 27: @@
 The longword operations implement byte and word modes required by certain I/O devices.
-The XMI has a 64 ns bus cycle.
+The XMI has a 64 ns bus cycle. It has a bandwidth of 100 Mbytes per second; however, the usable bandwidth depends on transaction length:
 {| class="wikitable"
@@ Line 43: / Line 49: @@
 |}
-== XMI Versions ==
+==XMI Versions==
 The XMI bus started with the "+5V '''XMI-1'''" version which was developed to the "+3.3V '''XMI-2'''" version later on.
-There was an upgrade kit option H9657-CU that takes a VAX 6000 Model 200, 300, or 400 system with an XMI-1 power system and upgrades it to a VAX 6000 Model 500 with an XMI-2 power system.
+There was an upgrade kit option H9657-CU that takes a VAX 6000 Model 200, 300, or 400 system with an XMI-1 power system and upgrades it to a VAX 6000 Model 500 with an XMI-2 power system. The upgrade adds +3.3 volt power, an XMI-2 backplane preassembled with bus bars and cables, and an H7206-B power and logic unit.
 {{semi-stub}}
@@ Line 57: / Line 60: @@
 * [http://www.bitsavers.org/pdf/dec/vax/6200/EK-620AA-TM-001_Tech_May88.pdf VAX 6200 Technical User's Guide] (EK-620AA-TM-001) - the XMI is covered in Chapter 2, pp. 37-91 of the PDF
 [[Category: DEC Buses]]
 [[Category: XMI]]
 [[Category: VAXen]]

← Older revision		Revision as of 11:44, 17 March 2023
Line 60:		Line 60:
	[[Category: DEC Buses]]		[[Category: DEC Buses]]
	[[Category: XMI]]		[[Category: XMI]]
		+	[[Category: VAXen]]

@@ Line 1: / Line 1: @@
 The Extended Memory Interconnect (acronym: XMI) was a bus introduced with the [[VAX 6000 series]] of [[Digital Equipment Corporation|DEC]] computers to cope with increased requirements, e.g bandwidth.
 The XMI bus started with the "+5V '''XMI-1'''" version which was developed to the "+3.3V '''XMI-2'''" version later on.
@@ Line 7: / Line 50: @@
 The upgrade adds +3.3 volt power, an XMI-2 [[backplane]] preassembled with bus bars and cables, and an H7206-B power and logic unit.
-[http://www.vaxhaven.com/images/f/fc/EK-650EB-UP-002.pdf EK-650EB-UP-002 VAX 6000 XMI Conversion Manual] describes the upgrade procedure.
+The manual [http://www.vaxhaven.com/images/f/fc/EK-650EB-UP-002.pdf EK-650EB-UP-002 VAX 6000 XMI Conversion Manual] describes the upgrade procedure.
-{{stub}}
+{{semi-stub}}
 [[Category: DEC Buses]]
 [[Category: XMI]]