Re: [9fans] PDP11

["Digby R.S. Tarvin" <digbyt42@gmail.com>]

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Yes, that is exactly what prompted the thinking about Plan9 on a PDP11/70.
I have already organized a PiDP11 kit to be shipped to me when I get home
in December  - so that I can experiment without running the risk of blowing
up my old original 11/70 front panel. But a (simulated) 11/70 with a nice
front panel isn't so interesting unless I have some interesting PDP11
software to run on it.

A small Plan9/Inferno implementation could be integrated into a larger
network and allow the old hardware to integrate seamlessly with other
things. Such as exporting a device that lets other hosts write to the
lights and read from the switches, for example..

Regards.
DigbyT

On Tue, 9 Oct 2018 at 14:23, David Arnold <davida@pobox.com> wrote:

> On 9 Oct 2018, at 14:08, Digby R.S. Tarvin <digbyt42@gmail.com> wrote:
>
>
> <…>
>
> So I don't think it i would be worth a substantial rewrite to get it
>>> going. It is a shame that there don't seem to have been any more powerful
>>> machines with a comparably elegant architecture and attractive front panel
>>> :)
>>>
>>
>> An attractive front panel for nearly any machine is just a soldering
>> iron, LEDs and some logic chips away. As far as elegant architectures, some
>> are very nice: MIPS is kind of retro but elegant, RISC-V is nice, 680x0
>> machines can be had a reasonable prices, and POWER is kind of cool. I know
>> I shouldn't, but I have a soft spot for ARM.
>>
>
> I have thought about it, but there are a couple of problems (in addition
> to my lack artistic talent when it comes to building physically attractive
> enclosures)..  One is the sheer number of LEDs required to display all of
> the address and data lines in a modern architecture.  Mainly an issue if I
> want to use the old PDP11/70 front panel that I had saved for the purpose,
> I suppose. The other problem is getting access to the all of the machine
> state that was displayable on a mini computer console. Virtual addresses,
> User/Kernel mode, register contents etc are all hard to get at. I have
> toyed with using JTAG etc, but there always seems to be something that I
> can't get to. So it is hard to do more than resort to a software controlled
> front panel. I used to have a little box of LEDs and switches that I
> plugged into the parallel port on PCs, and had my BSDi kernel modified to
> update it as part of the clock interrupt. But now the parallel ports are
> becoming rare and you can't update LEDs connected via USB in a single
> instruction... :-/
>
>
> Probably not quite what you’re after, but the PiDP8 and PiDP11 kits will
> get you an (arguably) attractive front panel without requiring artistic
> talent.
>
>    http://obsolescence.wixsite.com/obsolescence/pidp-11
>
> I’ve not looked into how the front-panel is driven (from SIMH, I guess?),
> but perhaps it could be suitably massaged?
>
>
>
> d
>
>

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