Difference between revisions of "System unit"

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The initial system units were [[DEC card form factor|hex]] height, four-slot assemblies. (Sometimes a number of these were wired together to form a single unit, such as in the [[PDP-11/20]]'s [[KA11]] [[Central Processing Unit|CPU]], which used three.)
 
The initial system units were [[DEC card form factor|hex]] height, four-slot assemblies. (Sometimes a number of these were wired together to form a single unit, such as in the [[PDP-11/20]]'s [[KA11]] [[Central Processing Unit|CPU]], which used three.)
  
Late on, 'double' system units (also hex-height, but nine slots wide) appeared. There were also custom backplanes (such as for the [[PDP-11/45]] and [[PDP-11/70]], in the latter backplanes for both the CPU and memories such as the [[MJ11 memory system‎|MJ11]] and [[MK11 memory system‎|MK11]]) which were even wider than that, but generally a double was the maximum width for an option.
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Later on, 'double' system units (also hex-height, but nine slots wide) appeared. There were also custom backplanes (such as for the [[Central Processing Unit|CPUs]] of the [[PDP-11/45]] and [[PDP-11/70]]; in the latter backplanes for both the CPU and memories such as the [[MJ11 memory system‎|MJ11]] and [[MK11 memory system‎|MK11]]) which were even wider than that, but generally a double was the maximum width for an option.
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Each slot held six 'connectors', DEC's term for a [[DEC edge connector contact identification|group of edge connector pins]], denominated 'A'-'F'.
  
 
All the DEC chassis boxes (such as the [[BA11-K]] and [[BA11-L]]) had mechanical mountings and DC power connectors intended to hold system units.
 
All the DEC chassis boxes (such as the [[BA11-K]] and [[BA11-L]]) had mechanical mountings and DC power connectors intended to hold system units.
  
 
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[[Category: DEC Hardware]]

Latest revision as of 14:45, 23 December 2023

A system unit is a standard modular backplane from DEC, used mostly in UNIBUS PDP-11s.

The initial system units were hex height, four-slot assemblies. (Sometimes a number of these were wired together to form a single unit, such as in the PDP-11/20's KA11 CPU, which used three.)

Later on, 'double' system units (also hex-height, but nine slots wide) appeared. There were also custom backplanes (such as for the CPUs of the PDP-11/45 and PDP-11/70; in the latter backplanes for both the CPU and memories such as the MJ11 and MK11) which were even wider than that, but generally a double was the maximum width for an option.

Each slot held six 'connectors', DEC's term for a group of edge connector pins, denominated 'A'-'F'.

All the DEC chassis boxes (such as the BA11-K and BA11-L) had mechanical mountings and DC power connectors intended to hold system units.