Re: [9fans] PDP11

[David Arnold <davida@pobox.com>]

[-- Attachment #1.1: Type: text/plain, Size: 2054 bytes --]

> 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


[-- Attachment #1.2: Type: text/html, Size: 3271 bytes --]

[-- Attachment #2: Message signed with OpenPGP --]
[-- Type: application/pgp-signature, Size: 849 bytes --]