Difference between revisions of "MS11-K MOS memory"

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The '''MS11-K MOS memory''' modules were the memory array modules used in the [[MK11 memory system]] for the [[PDP-11/70]].
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The '''MS11-K MOS memory''' modules were the first generation of memory array modules used in the [[MK11 memory system]] for the [[PDP-11/70]]. (The functional difference between the 256KB version of the MS11-K, and the later M8728, is currently unknown.)
  
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There were two generations of memory modules for the MK11.
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[[Image:MS11-KE.jpg|thumb|200px|right|MS11-KE 64KB module]]
  
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[[Image:MS11-KE.jpg|thumb|200px|right|MS11-KE 64KB module]]
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Each MS11-K module was a [[DEC card form factor|hex]] board, the M7984. Fully populated, the board holds a total of 156 [[Dynamic RAM|DRAM]] [[integrated circuit|chips]], including 28 to hold the [[Error-correcting code|ECC]]. According to the prints, it could be used with 4Kx1 chips, giving 64KB total storage; or 16Kx1, giving 256KB.
  
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The original memory module was the MS11-K (M7984). According to the prints, it could be used with 4Kx1 [[Dynamic RAM|DRAMs]] (giving 64KB with a total of 156 chips, including 28 to hold the ECC), or 16Kx1. Per the prints, these are the configurations and board types:
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Per the prints, these are the configurations and board types:
  
 
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(The 'x' in the board number is one of a nuber of letters, starting with 'A', which indicates the manufacturer of the DRAM chips used.)
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(The 'x' in the board number is one of a number of letters, starting with 'A', which indicates the manufacturer of the DRAM chips used.)
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The second memory array module is the M8728, which used 156 16Kx1 DRAMs to provide a 246KB module.
 
  
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A later board, the M8750, used the same [[Printed circuit board|PCB]] as the M8728, but 64Kx1 DRAM chips - the board had jumpers to allow the use of either size chip - to provide a 1MB card.
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It is not confirmed exactly what the difference is between the -KA and the -KE; the prints show the latter as a replacement for the former, and describe the latter's RAM chips as "fast RAM" (200nsec versus 75nsec).
  
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This board was not supported by the MK11. However, it is possible to use them in an MK11 with slight modifications. Also, it is theorized that with the appropriate jumper setting, they can be made to look like 256 boards.
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[[Category: PDP-11 Memories]]

Latest revision as of 02:24, 6 February 2024

The MS11-K MOS memory modules were the first generation of memory array modules used in the MK11 memory system for the PDP-11/70. (The functional difference between the 256KB version of the MS11-K, and the later M8728, is currently unknown.)

MS11-KE 64KB module

Each MS11-K module was a hex board, the M7984. Fully populated, the board holds a total of 156 DRAM chips, including 28 to hold the ECC. According to the prints, it could be used with 4Kx1 chips, giving 64KB total storage; or 16Kx1, giving 256KB.

Per the prints, these are the configurations and board types:

Board Model Size Configuration
M7984-Ax MS11-KA 64KB 156 x 4K chips
M7984-Bx MS11-KB 32KB 78 x 4K chips
M7984-Cx MS11-KC 256KB 156 x 16K chips
M7984-Dx MS11-KD 64KB 39 x 16K chips
M7984-Ex MS11-KE 64KB 156 x 4K chips
M7984-Fx MS11-KF 128KB 78 x 16K chips

(The 'x' in the board number is one of a number of letters, starting with 'A', which indicates the manufacturer of the DRAM chips used.)

It is not confirmed exactly what the difference is between the -KA and the -KE; the prints show the latter as a replacement for the former, and describe the latter's RAM chips as "fast RAM" (200nsec versus 75nsec).

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