Stuck bits on 11/73 Clearpoint 4MB memory - how to repair?

Glen Slick glen.slick at
Fri Feb 12 20:32:10 CST 2016

On Fri, Feb 12, 2016 at 3:32 PM, Jacob Ritorto <jacob.ritorto at> wrote:
> Hi,
>     Seems I have bits 4 and 3 sticking on my Clearpoint QRAM-2-SAB-1 88b
> 4MB memory in my pdp11/73.
>     Can anyone offer hints as to how to identify which component is broken
> and how to go about repairing this?

Are the 256Kx1 DRAM chips in sockets? If they are it shouldn't be too
hard to come up with a scheme for exchanging some of the DRAM chips to
see if the stuck bits move and then work out which chip positions map
to which bits and then which DRAM chips need to be replaced.

More information about the cctalk mailing list