[rescue] huge DEC rescue in TX?

Jonathan C. Patschke jp at celestrion.net
Thu Feb 3 15:52:12 CST 2005

On Thu, 3 Feb 2005, Wai-Sun Chia wrote:

>> That's funny.  There are quite a lot of socketed chips on mine.
> I was refering to the CPU: i.e. there's no socketed CPUs like the
> PGA (socket 7), etc.

Well, again, it depends on the model.  The CPUs in the 11/23, 11/73, and
11/53 are socketed.  They're large DIPs, though, instead of PGAs.

> Yeah. The wierd thing is that even though a wire-wrapped backplane *LOOKS* 
> flimsy, it is quite robust indeed. The fact that they're still working after 
> 25-30 years is a testament of the engineering quality that goes into a 
> typical PDP.

Very true.  It's a shame that it's so impractical (to the point of being
impossible) at higher clock rates.  You really can't hack on modern
machines like you can on older stuff like that.  I mean, I'm going to
extend my 11/23's bus from 18-bits to 22-bits sometime in the future.
That's a very foreign concept in the microcomputer world.

>> I think the "CPU" is just a single 40-pin DIP.  The others are the MMU
>> and additional microcoded instructions.  Everything about that platform
> Well, to me a MMU and microcode are *part* of the CPU. :-)

Well, that's up for debate.  Microcode maybe, but not necessarily the

Jonathan Patschke   )   "Let me hear you make decisions
Elgin, TX          (     without your television."
USA                 )        --Depeche Mode, "Stripped"

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