Difference between revisions of "MMV11-A QBUS core memory"

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[[Image:MMV11-A.jpg|350px|thumb|right|MMV11-A board set, showing only the G653 mother-board]]
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'''MMV11-A''' is a [[core memory|core]] [[main memory]] module for the [[QBUS]] - the only core main memory from [[Digital Equipment Corporation|DEC]] for the QBUS.
 
'''MMV11-A''' is a [[core memory|core]] [[main memory]] module for the [[QBUS]] - the only core main memory from [[Digital Equipment Corporation|DEC]] for the QBUS.
  
An MMV11-A card holds 8K [[byte]]s; it has an [[access time]] of 425 nsec, and a [[cycle time]] of 1.15 μsec.
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An MMV11-A holds 8K [[byte]]s; it has an [[access time]] of 425 nsec, and a [[cycle time]] of 1.15 μsec.
  
 
An MMV11-A was composed of two [[DEC card form factor‎|quad-sized]] boards, one piggy-backed on the other, and the pair taking only a single [[backplane]] slot (electrically):
 
An MMV11-A was composed of two [[DEC card form factor‎|quad-sized]] boards, one piggy-backed on the other, and the pair taking only a single [[backplane]] slot (electrically):
  
* An H223 daughter-board containing the cores
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* An H223 [[daughter-board]] containing the cores
 
* A G653 mother-board containing most of the electronics, and the contact fingers for plugging into the [[backplane]].
 
* A G653 mother-board containing most of the electronics, and the contact fingers for plugging into the [[backplane]].
  
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The MMV11-A was a [[QBUS#Variable_address_size|Q16]] card, so could only be used on systems with a maximum of 64KB of memory.
 
The MMV11-A was a [[QBUS#Variable_address_size|Q16]] card, so could only be used on systems with a maximum of 64KB of memory.
  
{{PDP-11}}
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==See also==
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* [[QBUS memories]]
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==External links==
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* [http://www.bitsavers.org/pdf/dec/pdp11/1103/EK-LSI11-TM-002.pdf LSI-11, PDP-11/03 user's manual] (EK-LSI11-TM-002) - the MMV11-A is covered in Section 4.3 (pp. 52-62 of the PDF) and Chapter 8 (pp. 111-112 of the PDF)
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* [http://www.bitsavers.org/pdf/dec/qbus/Digital_Microcomputer_Processor_Handbook_1979_80.pdf microcomputer processor handbook] - the MMV11-A is covered on Chapter 12, pp. 367-384 (pp. 377-394 of the PDF)
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* [http://bitsavers.org/pdf/dec/pdp11/handbooks/Microcomputer_Handbook_1976-1977.pdf Microcomputer Handbook (1976-77)] - the MMV11-A is covered on pp. 4-16—4-30 and 5-11—5-14 (pp. 99-113 and 164-167 of the PDF)
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* [http://bitsavers.org/pdf/dec/qbus/MP00706-ET-LSI-11_Dec81.pdf ET-LSI-11 Field Maintenance Print Set] (MP00706) - the MMV11-A covered on pp. 170-177
  
 
[[Category: QBUS Memories]]
 
[[Category: QBUS Memories]]

Latest revision as of 19:26, 13 July 2023

MMV11-A board set, showing only the G653 mother-board

MMV11-A is a core main memory module for the QBUS - the only core main memory from DEC for the QBUS.

An MMV11-A holds 8K bytes; it has an access time of 425 nsec, and a cycle time of 1.15 μsec.

An MMV11-A was composed of two quad-sized boards, one piggy-backed on the other, and the pair taking only a single backplane slot (electrically):

  • An H223 daughter-board containing the cores
  • A G653 mother-board containing most of the electronics, and the contact fingers for plugging into the backplane.

The MMV11-A did not use a custom backplane; it plugged into a standard Q/Q backplane. However, it did use QBUS signals on the right-hand C/D connectors, so it could not be plugged into a Q/CD backplane.

The pair was 'thick' enough that a normal board cannot be plugged into the next slot. DEC documentation indicates that if there are devices 'behind' the MMV11-A on the bus, the bus grant lines (BIAK and BDMG) must be jumpered on the backplane in that slot.

The MMV11-A was a Q16 card, so could only be used on systems with a maximum of 64KB of memory.

See also

External links