View source for MM11-E and MM1-F core memories

[[Image:H207CoreStack.jpg|300px|right|thumb|H207 core stack]]

The '''MM11-E''' and '''MM11-F core memories''' were [[UNIBUS]] [[main memory]] units; the first UNIBUS memories produced by [[Digital Equipment Corporation|DEC]]. They came out with/for the first [[PDP-11]], the [[PDP-11/20]].

They were very similar - both 4K [[word]] (8K [[byte]]s), and with most of their boards in common. The MM11-F was capable of [[memory interleaving|interleaving]] (although this capability was then made available to the MM11-E as well); it also had a [[parity]] version available, the '''MM11-FP''' (which used a 4Kx18 [[core memory|core plane]], instead of the 4Kx16 used in the MM11-E and MM11-F).

The MM11-F was also slightly faster: the MM11-E had an [[access time]] of 500 nsec and a [[cycle time]] of 1.2 μsec; the MM11-F had an access time of 400 nsec and a cycle time of 980 nsec.

==Implementation==

Both consisted of a [[DEC card form factor|quad-width]] H207 (non-parity) or H210 (parity) core plane board (the H2xx board consisted of a G617 and a G616 Planar Stack boards), along with a number of dual- and single-width cards (all [[DEC card form factor|extended-length]]), plugged into a custom-wired quad [[system unit]] [[backplane]]. The MM11-F and MM11-FP used the same backplane; only the board set was slightly different.

The MM11-E consisted of:

* H207 core plane (quad)
* M729 Control Logic (dual)
* 4 x G102 Sense Inhibit
* G103 Levels and Gates
* G225 Current Generator
* 4 x G226 Decoder and Switch
* M109 Device Select

The MM11-F consisted of:

* H207 or H210 core plane (quad)
* M7290 Control Logic (dual)
* 4 x G102 Sense Inhibit
* G103 Levels and Gates
* G108 Sense-Inhibit (-FP only)
* G225 Current Generator
* 4 x G226 Decoder and Switch
* M1091 Device Select

So the only major difference is the M7290 Control Logic, instead of the M729.

===Board locations===

These are the board locations for the MM11-E (as seen from the board side of the backplane):

{| class="wikitable"
! Connector !! Slot 4 !! Slot 3 !! Slot 2 !! Slot 1
|-
| A || rowspan="2" style="text-align:center;" | UNIBUS<br>Out || Power || &nbsp; || rowspan="2" style="text-align:center;" | UNIBUS<br>In
|-
| B || &nbsp; || M109! 
|-
| C || rowspan="4" style="text-align:center;" | H207 || G226 || G226 || rowspan="2" style="text-align:center;" | M729
|-
| D || G102 || G102
|-
| E || G102 || G102 || G225
|-
| F || G226 || G226 || G103 
|}

! = Possibly the later M1091: the M1091 could be used in the MM11-E as well as the MM11-F; it appears that later units of the MM11-E shipped with the M1091. The difference between the M109 and M1091 is the addition of additional [[jumper]]s to allow interleaving.

These are the board locations for the MM11-F and -FP (as seen from the board side of the backplane):

{| class="wikitable"
! Connector !! Slot 4 !! Slot 3 !! Slot 2 !! Slot 1
|-
| A || rowspan="2" style="text-align:center;" | UNIBUS<br>Out || Power || &nbsp; || rowspan="2" style="text-align:center;" | UNIBUS<br>In
|-
| B || G225 || M1091 
|-
| C || rowspan="4" style="text-align:center;" | H207<br>or<br>H210 || G226 || G226 || rowspan="2" style="text-align:center;" | M7290
|-
| D || G102 || G102
|-
| E || G102 || G102 || G108@
|-
| F || G226 || G226 || G103 
|}

@ = MM11-FP only

==External links==

* [http://bitsavers.org/pdf/dec/pdp11/memory/MM11-E_CoreMemoryManual.pdf MM11-E Core Memory Manual] (DEC-11-HR3A-D) - includes engineering drawings on pp. 24-41 <!-- also http://shop-pdp.net/~stuff/PDFs/DEC/DEC-11-HR3B-D_MM11-E_Core_Memory_Manual_Mar71.pdf -->
* [http://ana-3.lcs.mit.edu/~jnc/tech/pdp11/dload/DEC-11-HMFA-D_MM11-F_Manual.pdf MM11-F core memory manual] (DEC-11-HMFA-D)
** [http://ana-3.lcs.mit.edu/~jnc/tech/pdp11/dload/MM11-F_Manual.tar MM11-F core memory manual] - scans of individual pages in a [[tar]] file
* [http://ana-3.lcs.mit.edu/~jnc/tech/pdp11/dload/DEC-11-HMFA-D_MM11-F_Drawings.pdf MM11-F core memory engineering drawings] (DEC-11-HMFA-D)
** [http://ana-3.lcs.mit.edu/~jnc/tech/pdp11/dload/MM11-F_Drawings.tar MM11-F ore memory engineering drawings] - scans of individual pages in a tar file

[[Category: UNIBUS Memories]]