[rescue] huge DEC rescue in TX?

Wai-Sun Chia waisun.chia at hp.com
Thu Feb 3 06:01:16 CST 2005

Jonathan C. Patschke wrote:
> On Wed, 2 Feb 2005, Wai-Sun Chia wrote:
>> PDPs doesn't even have socket arrays!
> 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.

>> That's why they last so long! The Unibus PDPs have all discrete TTL
>> CPUs; i.e. the CPU is implemented in multiple boards.
> That is, indeed the case.  The point I was making was that the craziest
> they got with connecting things together was the occasional socket here
> and there.  Most everything else is soldered or, in the case of the
> backplane, wire-wrapped together.

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.

> 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. :-)
If DEC had the technology then, they would've just crammed everything 
into a single 40-pin DIP (just like the i386 and i387).

> is an amazing study in efficiency and conservative[0] engineering.
> [0] Well, aside from the 11/70.  There's -nothing- conservative about
>     that beast.

Well, try a KL10! This uses 12.6kW (3ph at 35A/ph/120V) just for the 
processor; no core, no disks, no peripherals!!


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