[HECnet] Tops-20 ANONYMOUS FAL Preliminary Testing Results/DAP Query

[John Forecast]

> On Dec 20, 2019, at 11:21 PM, Thomas DeBellis <tommytimesharing at gmail.com> wrote:
> 
> Indeed; but there was a time when the PDP-11's 16 bit (64K) address space and eight register file seemed positively generous.  That's when you compare it to the PDP-8's single accumulator and 12 bit (4K) address space.
> 
> I continue to be astounded what they managed to do with that.  In addition to a nice package of languages, with a memory management unit (essentially a bank switcher), they got the thing to timeshare.  That's right; TSS-8.  There's one still running at the Computer History Museum on an 8/I.
> 
> So they got DECnet running on the PDP-8?  Wow.  I wonder how they did that; whether they re-targeted a BLISS compiler to emit PAL.  I remember looking at the source to PDP-8 VT (video) TECO.  Many awe most inspiring kludges.  What a tour de force.  Very humbling.
> 
> 
That was implemented on RTS-8 and looks like a Phase I implementation - all hand-crafted PAL code. The floppies are available on the net and includes full source code. When I joined the DECnet development group in early 1977, there were a couple of PDP-8 developers as part of the group. I don’t know if they were developing a Phase II implementation but they disappeared after about 6 months - not surprising given the difficulties we were having getting it to fit in a 28KW PDP-11.

  John.

> The Algol compiler on the 20 has more than 2 bugs...  Sigh...
> 
>> 
>> On 12/20/19 9:08 PM, Paul Koning wrote
>> If you go far enough back, the space efficiency gets pretty amazing.  There's RSTS-11, which ran 16 timesharing users on a 28kW PDP-11/20. (Not well, but it ran.)  Or RT-11, quite comfortable in 8 kW and a 256 kbyte system disk.  Or DOS-11, which would even run, I think, in 4 kW.
>> 
>> Somewhat earlier still, in 1961 two people implemented the first ever ALGOL compiler in 6 months, and it ran on a 4 kW machine (27 bit).  (It's known to have two bugs.)
>> 
>> 	paul
>>> 
>>> On Dec 20, 2019, at 8:51 PM, Thomas DeBellis <tommytimesharing at gmail.com> <mailto:tommytimesharing at gmail.com> wrote:
>>> ...
>>> But the mini-computer operating systems are just plain cool.  It is amazing what they squeezed into the PDP-8's 12 bit address space and PDP-11's run some of the most interesting collection of OS's that I've ever seen.

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