MS11-LD (M7891-DA)

[Wai-Sun Chia]

On 2/6/06, Don North <ak6dn at mindspring.com> wrote:
> Wai-Sun Chia wrote:
> > Quick one:
> > Can I plug a M7891-DA into a 11/44?
> > This is supposed to be 128kW MOS RAM for the 11/24 and 11/34A...
> >
> > BTW, what kinds of memory options/expansions does a 11/44 have?
> >
> >
> >
> I believe the M7891 (MS11-Lx) is compatible with the 11/44 memory slots,
> but it needs to have some jumpers changed to allow this:
>
> 1) Change from MODIFIED UNIBUS (MUD, 18b) to EXTENDED UNIBUS (EUB, 22b)
> decoding.
>    Jumper W4:  MOD/IN  EUB/OUT
>
> 2) Change from +15V supply (MUD slot) to +12V supply (EUB slot, 11/44
> backplane).
>    Jumpers W1&W2:  +15v/W1-OUT,W2-IN  +12v/W1-IN,W2-OUT
>
> The MS11-Lx is a parity module, up to 256KB density. More standard
> memory options for the 11/44 would be MS11-Mx 256KB ECC, and MS11-Px
> 1024KB ECC.

Hey, thanks for the detailed slot hacking procedures! :-)
I didn't know that one could use a MS11-Px and save 3 slots tto get
1MB on a 11/44!!

So theoretically I can cram 4 MS11-Px boards to achieve full 22bits
(4MB) RAM on a 11/44??