23 Dec
2019
23 Dec
'19
8:24 p.m.
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.