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

[Göran Åhling]

11/21 Falcon board, ie KXT11-{AA|AB|BA|CA}  is a single-board, 
"Dual-wide" (to use DEC descriptions counting the number of contact 
finger groups on the card-edge) for earlier versions, quad-wide for -CA 
PDP-11 CPU board with integrated memory and 2 or 3 serial ports. The 
last version could have memory up to 64 kB on-board, slightly earlier 
version max 48 kB, the first version 4 kB. "The OEM computer" of those 
days - compare it to an ARM or PIC-chip of today. CPU is the T-11 chicp, 
ie generation 2 out of 4 integrated generations. Picture of dual-wide 
type at: http://www.conticomp.com/item_show.cfm?itemID=157659

BUT: The last fine PDP-11 by DEC was the PDP11-93 CPU. This was built as 
a single-card computer, quad-wide Q-bus, integrated memory (2 or 4 
MBytes depending on version/price), integrated 8 serial lines, 
integrated boot-rom etc. CPU is the J-11, ie generation 4 out of 4 
integrated designs.

So, physically, both these are the same, but the later has more of 
horsepowers in it's CPU. Both of them would do the job you have 
described, the latter would do it eassily...

(All "early" PDP-11:s were built upon MSI logic, so a CPU would need at 
least a few cards, each hex-wide size.)

When it comes to the architecture, The PDP11-20 (with oem name PDP11-15) 
was first. This one ha the "smallest" architecture, with a minimum of 
features. To design the "smallest" PDP-11 emulator, an 11-20 should be 
emulated (I think there is an FPGA-code on the net for this CPU). This 
one has 16 bits of adress, ie max 64 kB memory.

For OS:es, RT-11 is certainly the "smallest" of those that were offered 
by DEC in the later part of the PDP-11 era. RT-11 can run on most system 
configurations, using minimum floppy or TU-58 tape drive as secondary 
storage.

The TU-58 tape-drive was connected using one serial port. PC-based 
emulators of this 1/4" tape drive exists freely today (using PC with 
COM-port).

One small system to "copy" in config could possibly be a PDT11-150 or a 
VT103 aka PDT11-110 and/or PDT11-130. Actual config of these should be 
possible to find online...

As for emulations, this coule of today be run in a system not much 
larger than a coin...

More information can be read at:
http://hampage.hu/pdp-11/main.html
http://en.wikipedia.org/wiki/PDP-11
and at lots of other fine sites through the net.

/Göran

On 2012-07-05 19:03, Alan Frisbie wrote:
>> And people who "know" PDP-11s are asking them self "smallest
>> pdp-11",  what is that?
> The smallest one I recall was put together by John Crowell,
> and was based on an 11/21 "Falcon" board.   My memory is a
> bit hazy (hey, it was 30 years ago!), but it had one or two
> TU58 drives and ran RT-11 (anyone who knows John would not
> be surprised by that).   Since it was used for collecting
> data in the field, he called it the Field-11.
>
> Somewhere in my archives I have a magazine article about it.
>
> I'm sure there were even smaller ones based on the T-11 chip.
>
> Alan Frisbie
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