QBUS backplanes - Revision history

Jnc: Clarify that not just aperipherls can go in QBUS slots

2024-08-26T16:57:43Z

Clarify that not just aperipherls can go in QBUS slots

Jnc: Switch to standard wording; add link

2024-08-25T11:24:53Z

Switch to standard wording; add link

Vaxorcist: /* DEC backplanes */ H9274 VT103 backplane added

2024-08-17T07:11:22Z

‎DEC backplanes: H9274 VT103 backplane added

Jnc: Minor clarity improvements

2024-07-30T14:29:20Z

Minor clarity improvements

Jnc: /* DEC Backplanes */ Change column title to '# slots'

2024-07-30T01:33:21Z

‎DEC Backplanes: Change column title to '# slots'

Jnc: /* Further reading */ +Micro Backplane Mechanical Mounting Guidelines

2024-07-27T16:45:27Z

‎Further reading: +Micro Backplane Mechanical Mounting Guidelines

Glitch: /* MDB Backplanes */

2024-07-24T18:33:44Z

‎MDB Backplanes

Glitch: /* MDB Backplanes */

2024-07-24T18:33:36Z

‎MDB Backplanes

Glitch: /* MDB Backplanes */

2024-07-24T18:32:13Z

‎MDB Backplanes

Glitch: Adding MDB Systems backplane subsection, giving DEC backplanes a subsection

2024-07-24T18:21:58Z

Adding MDB Systems backplane subsection, giving DEC backplanes a subsection

@@ Line 1: / Line 1: @@
 '''QBUS backplanes''' come mostly in two physical types, [[DEC card form factor|dual-width]] and quad-width. In the quad-width [[backplane]]s, each slot held four 'connectors' (DEC's term for a group of [[DEC edge connector contact identification|edge connector pins]]), denominated 'A'-'D'.
-The [[QBUS]] itself is fully carried in a dual slot, and the backplanes with quad slots are further sub-divided into two types, the so-called '''Q/Q''' and '''Q/CD'''. In quad Q/Q units, both sides (pairs of 'connectors') of each quad slot are fully wired for QBUS, and so a single slot can hold two separate dual-width QBUS [[peripheral controller|devices]]. The device locations are usually arranged for [[bus grant line|grant]] priority in so-called 'serpentine' order, i.e. one with the devices in the following order (facing the backplane from the board side):
+The [[QBUS]] itself is fully carried in a dual slot, and the backplanes with quad slots are further sub-divided into two types, the so-called '''Q/Q''' and '''Q/CD'''. In quad Q/Q units, both sides (pairs of 'connectors') of each quad slot are fully wired for QBUS, and so a single slot can hold two separate dual-width QBUS [[peripheral controller|device]], [[main memory|memory]], etc [[printed circuit board|cards]]. The device locations are usually arranged for [[bus grant line|grant]] priority in so-called 'serpentine' order, i.e. one with the devices in the following order (facing the backplane from the board side):
 -2<br>4-3<br>5-6<br>8-7<br>9-10

@@ Line 1: / Line 1: @@
-'''QBUS backplanes''' come mostly in two physical types, [[DEC card form factor|dual-width]] and quad-width. In the quad-width [[backplane]]s, each slot held four 'connectors' (denominated 'A'-'D'), DEC's term for a [[DEC edge connector contact identification|group of edge connector pins]].
+'''QBUS backplanes''' come mostly in two physical types, [[DEC card form factor|dual-width]] and quad-width. In the quad-width [[backplane]]s, each slot held four 'connectors' (DEC's term for a group of [[DEC edge connector contact identification|edge connector pins]]), denominated 'A'-'D'.
-The [[QBUS]] itself is fully carried in a dual slot, and the backplanes with quad slots are further sub-divided into two types, the so-called '''Q/Q''' and '''Q/CD'''. In quad Q/Q units, both sides of each quad slot are fully wired for QBUS, and so a single slot can hold two separate dual-width QBUS [[peripheral controller|devices]]. The device locations are usually arranged for grant priority in so-called 'serpentine' order, i.e. one with the devices in the following order (facing the backplane from the board side):
+The [[QBUS]] itself is fully carried in a dual slot, and the backplanes with quad slots are further sub-divided into two types, the so-called '''Q/Q''' and '''Q/CD'''. In quad Q/Q units, both sides (pairs of 'connectors') of each quad slot are fully wired for QBUS, and so a single slot can hold two separate dual-width QBUS [[peripheral controller|devices]]. The device locations are usually arranged for [[bus grant line|grant]] priority in so-called 'serpentine' order, i.e. one with the devices in the following order (facing the backplane from the board side):
 -2<br>4-3<br>5-6<br>8-7<br>9-10

@@ Line 29: / Line 29: @@
 |-
 | [[H9273 backplane|H9273]] || Q/CD || 9 || Q18 || [[BA11-N mounting box|BA11-N]] || none
 |-
 | H9275 || Q/Q || 9 || Q22 || &nbsp;|| 120 ohms

@@ Line 1: / Line 1: @@
-'''QBUS backplanes''' come mainly in two physical types, [[DEC card form factor|dual-width]] and quad-width. In the quad-width [[backplane]]s, each slot held four 'connectors', DEC's term for a [[DEC edge connector contact identification|group of edge connector pins]], denominated 'A'-'D'.
+'''QBUS backplanes''' come mostly in two physical types, [[DEC card form factor|dual-width]] and quad-width. In the quad-width [[backplane]]s, each slot held four 'connectors' (denominated 'A'-'D'), DEC's term for a [[DEC edge connector contact identification|group of edge connector pins]].
-The [[QBUS]] itself is fully carried in a dual slot, and the quads are further sub-divided into two types, the so-called '''Q/Q''' and '''Q/CD'''. In quad Q/Q units, both sides of each quad slot are fully wired for QBUS, and so a single slot can hold two separate dual-width QBUS [[peripheral controller|devices]]. The device locations are usually arranged for grant priority in so-called 'serpentine' order, i.e. one with the devices in the following kind of order (facing the backplane from the board side):
+The [[QBUS]] itself is fully carried in a dual slot, and the backplanes with quad slots are further sub-divided into two types, the so-called '''Q/Q''' and '''Q/CD'''. In quad Q/Q units, both sides of each quad slot are fully wired for QBUS, and so a single slot can hold two separate dual-width QBUS [[peripheral controller|devices]]. The device locations are usually arranged for grant priority in so-called 'serpentine' order, i.e. one with the devices in the following order (facing the backplane from the board side):
 -2<br>4-3<br>5-6<br>8-7<br>9-10
@@ Line 9: / Line 9: @@
 In a quad Q/CD backplane, the [[DEC edge connector contact identification|CD connectors]] form a private bus, sometimes called the [[CD interconnect]], used to connect together board pairs. (The CD connectors run down the right-hand side, when facing the side of the backplane where the boards plug in, with the CPU at the top.)
-It is usually possible to upgrade 18-bit backplanes to 22-bit; see [[Upgrading QBUS backplanes]].
+It is usually possible to upgrade [[QBUS#Variable address size|18-bit QBUS]] backplanes to 22-bit; see [[Upgrading QBUS backplanes]].
 '''''NOTE WELL:''''' For reasons which seem utterly incomprehensible, many boards designed for Q/CD slots (such as [[Private Memory Interconnect|PMI]] cards) '''do not''' avoid the QBUS pins on the CD connectors which contain 'hazardous' (to TTL circuitry) voltages. [''NOTE:'' The exact failure mode here is still not understood; the PMI spec was examined, but no clash of pin assignments was found. The warning is accurate, though: [https://www.ibiblio.org/pub/academic/computer-science/history/pdp-11/hardware/micronotes/numerical/micronote28.txt MicroNote #28] says "MSV11-J MODULES CAN[NOT] BE PLACED IN A Q/Q BACKPLANE SLOT. IF THIS IS ATTEMPTED PERMANENT DAMAGE WILL BE DONE TO THE BOARDS".] So, plugging such a card into a Q/Q backplane will generally '''''destroy''''' the card.
@@ Line 15: / Line 15: @@
 ==Backplane types==
-Several manufacturers produced QBus compatible backplanes:
+Several manufacturers produced QBUS compatible backplanes:
-===DEC Backplanes===
+===DEC backplanes===
 The following table lists the backplanes produced by [[Digital Equipment Corporation|DEC]]:
@@ Line 49: / Line 49: @@
 The DDV11-C details are somewhat speculative; in the [[VS11 Graphic System|VS11]], it is used with a [[VSV11 Graphic System|VSV11]], and the VSV11's Video Bus is carried over the E-F connectors. Puzzlingly, the VS11 documentation shows that a DDV11-D may also be used - but it claims to have the E-F connectors un-wired.
-===MDB Backplanes===
+===MDB backplanes===
-[[MDB Systems]] produced many third-party QBus options, including backplanes and complete chassis systems:
+[[MDB Systems]] produced many third-party QBUS options, including backplanes and complete chassis systems:
 {| class="wikitable"
-! ID !! Type !! Width || Address Width !! Assembly || Chassis !! Termination || Comments
+! ID !! Type !! # Slots || Address Width !! Assembly || Chassis !! Termination || Comments
 |-
 | [[40328]] || Q/Q || 8  || Q18 || [[MLSI-BPA84]] || [[MLSI-BA11-200]] || none || Wire wrap pins, can be wrapped to Q22
 |}
-'Type' indicates slot height and wiring, a value with a slash indicates quad height slots. 'Width' is the number of slots; if the backplane is quad-height, twice as many dual-height modules will fit.
+'Type' indicates slot height and wiring, a value with a slash indicates quad height slots. <!-- if the backplane is quad-height, twice as many dual-height modules will fit. - removed as duplicative of the note under the table above -->
-As with DEC backplanes, MDB backplanes that are Q/Q will damage QBus cards with CD interconnects.
+As with DEC backplanes, MDB backplanes that are Q/Q will damage QBUS cards with CD interconnects.
 ==Further reading==

@@ Line 22: / Line 22: @@
 {| class="wikitable"
-! ID !! Type !! Height || Address Width !! Chassis !! Termination || Comments
+! ID !! Type !! # Slots || Address Width !! Chassis !! Termination || Comments
 |-
 | [[H9270 backplane|H9270-A]] || Q/Q || 4  || Q18 || [[BA11-M mounting box|BA11-M]] || none
@@ Line 45: / Line 45: @@
 |}
-'Type' indicates whether it is dual-width ('Q') or quad. 'Height' is the number of slots; the number of dual-width board which can be plugged in is twice this, for Q/Q quad backplanes.
+'Type' indicates whether it is dual-width ('Q') or quad. '# slots' is the number of slots; for Q/Q quad backplanes, the number of dual-width board which can be plugged in is twice this.
 The DDV11-C details are somewhat speculative; in the [[VS11 Graphic System|VS11]], it is used with a [[VSV11 Graphic System|VSV11]], and the VSV11's Video Bus is carried over the E-F connectors. Puzzlingly, the VS11 documentation shows that a DDV11-D may also be used - but it claims to have the E-F connectors un-wired.

← Older revision		Revision as of 16:45, 27 July 2024
Line 62:		Line 62:

	As with DEC backplanes, MDB backplanes that are Q/Q will damage QBus cards with CD interconnects.		As with DEC backplanes, MDB backplanes that are Q/Q will damage QBus cards with CD interconnects.
		+
		+	==Further reading==
		+
		+	* ''Micro Backplane Mechanical Mounting Guidelines'', [[MicroNote]] #026

	==External links==		==External links==

@@ Line 54: / Line 54: @@
 {| class="wikitable"
-! ID !! Type !! Width || Address Width !! Chassis !! Termination || Comments
+! ID !! Type !! Width || Address Width !! Assembly || Chassis !! Termination || Comments
 |-
-| [[40328]] || Q/Q || 8  || Q18 || [[MLSI-BA11-200]] || none || Wire wrap pins, can be wrapped to Q22, MLSI BPA-84 when mounted in a card cage
+| [[40328]] || Q/Q || 8  || Q18 || [[MLSI--BPA84]] || [[MLSI-BA11-200]] || none || Wire wrap pins, can be wrapped to Q22
 |}