cctalk Digest, Vol 105, Issue 66 - test-drb@ccmp.vtda.org

29 May 2012

Date: Tue, 29 May 2012 12:22:23 +0200 (CEST) From: Christian Corti 
<cc at informatik.uni-stuttgart.de> To: "General Discussion: On-Topic and 
Off-Topic Posts" <cctalk at classiccmp.org> Subject: Re: PDP-11/05 Control 
(M7261) won't deposit Message-ID: 
<alpine.DEB.2.02.1205291219530.8955 at linuxserv.home> Content-Type: 
TEXT/PLAIN; charset=US-ASCII; format=flowed On Sun, 27 May 2012, Jon 
Elson wrote:

...
 > >> Working on a PDP-11/05. The front panel
appears to work, I can step through 
>      [...]

...
   is likely the
write command is not getting to the memory.  There are a 
 bunch of ways to make a front panel work, but since this is a raw logic 
 machine (no microcode) they probably worked hard to minimize the logic 

Stop, the 11/10 and 11/05 are fully microcoded machines. So much that even 
the minimalistic switch front panel is handled in the CPU microcode. I've 
learned that when I repaired our 11/10.
Oh, yeah!  NOW I remember what an 11/05 is, the really short (3U?) machine
with the single-line front panel.  YES, for some reason I was thinking of
the 11/20 or whatever the first model was.  You are certainly right about
it being microcoded including the front panel control.  I did work on an
11/05 about 1980 or so.  We moved up to a used 11/45 and then got a
VAX 780.

Jon