PDP 11 Core Memory - H214 Memory Stack

Tom Gardner thomas.gardner at sbcglobal.net
Fri Nov 5 13:48:15 CDT 2010

There are several pictures of an 8 KiWord H214 Memory Stack posted on the
Internet, for example, see 


At least one DEC manual describes the H214 as having "16 memory mats
arranged in a planar pattern" but the photo referenced above (and many
others) show 20 memory mats arranged in a two x ten planar pattern. 

Two by ten is a very strange array for a machine that has a 16 bit word or
18 bits in one with the byte parity option. 

Can anyone explain what is going on? 


Note this is also posted to alt.sys.pdp11

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