[Simh] smallest pdp-11 that can run TECO and sockets(*)?

[Johnny Billquist]

I should point out that the LSI-11 does not have EIS in the basic CPU. 
It's an option you can add, which have both EIS and FIS (the KEV-11, 
horrible :-) ).
The LSI-11 is also 16-bit addresses only.

I tried finding any information about the speed of the thing, but 
failed. But I think it is actually slower than the 11/05...

Anyway, unless the OP actually aim to find a real 11/03, I fail to see 
the point here. An emulated machine will not perform or behave the same 
from a time point of view anyway, and since I've already pointed out 
that RT-11 will run on any PDP-11, and TECO runs under RT-11, any 
machine running RT-11 is essentially equivalent to the "smallest" 
(slowest) PDP-11 from a coding point of view.

What is left is actually writing the code, something that seems to get 
much less attention...

	Johnny

On 2012-07-07 15:33, Davis Johnson wrote:
> I would have to concur. I have a physical 11/05. The 11/05 (same CPU as
> the 11/10) and it is nowhere near as capable as an 11/03. For a while
> there DEC had a tendency to release two new machines at a time. One
> would out perform the previous flagship processor, probably not costing
> too much more. The other would be comparable with the previous flagship
> processor but at a lower cost. The 11/05 was the similar capability
> lower cost follow on to the 11/20.
>
> Comparing the 11/05 is slower than the 11/03 and lacking a bunch of
> useful instructions. The 11/05 is totally devoid of any memory
> management - 64K address space is all you get.
>
> You could not configure 64K, of course because of the reserved address
> space. Mine has 32K, which I suppose is a typical large configuration.
> Core memory was expensive. I suppose one could have added a 16K board
> and had 48K but justifying the expense would have been difficult.
>
> On 7/7/2012 3:14 AM, Göran Åhling wrote:
>> Well, I'd used the word "Weakest" to describe this aspect of a
>> computer...
>>
>> Without reading any PDP-11 architecture handbook (today), I'd like to
>> claim the initial design, the 11/20, to have the weakest architecture
>> within the PDP-11 family, it was released in 1970.
>>
>> Just as all (almost) PDP:s the customer would order a CPU, and
>> separately order as much or little of memory that was regarded
>> "neccesary" for every task... 11/20 had a max. of 56 kB (28 kW), as
>> the design has 16 bits of adressing (=64 kB), but 8 kB are reserved
>> for I/O devices.
>>
>> Exactely how little memory that would be enough to run an OS, Teco and
>> an async port, I can't judge, but running an emulator, like SIMH,
>> would alow for testing of this. The 11/20 was sold along with core
>> memory, so a fair core memory card size for the minimum system would
>> be elegant...
>>
>> The instruction set of a PDP-11 was slightly extended with EIS for
>> modells comming just a few years later,  as several options (floating
>> point support, commersial calculations support,  memory management for
>> 18 or 22 bits of address-space...)
>>
>> But, as Johnny says, the LSI-11, aka PDP11-03, beeing the first
>> LSI-design from DEC, released in 1975 with the new LSI-bus (aka Q-bus)
>> is always remembered as the slowest PDP of all times, even though the
>> architecture might be slightly improved over 11/20!
>>
>> If you would like a running real physical system, the 11/03 would by
>> far be the easier to get hold of, get running, and keep running. The
>> 11/20 would typically need 2 pcs of 19" wide, 72" high racks... For
>> emulation, this is however not an issue!
>>
>> /Göran
>>
>> On 2012-07-06 21:04, Richard wrote:
>>> When I say "small", I'm referring to computational capacity, not
>>> physical dimensions.
>>
>>
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>>
>>
>
>
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-- 
Johnny Billquist                  || "I'm on a bus
                                   ||  on a psychedelic trip
email: bqt at softjar.se             ||  Reading murder books
pdp is alive!                     ||  tryin' to stay hip" - B. Idol