Portable PDP-11 (was Re: Does anyone use RT-11?)

[Ethan Dicks]

On 9/10/07, Allison <ajp166 at bellatlantic.net> wrote:
> >   "Ethan Dicks" <ethan.dicks at gmail.com wrote:
> >
> >On 9/9/07, Allison <ajp166 at bellatlantic.net> wrote:
> >> One day I plan to get a T11 up and running wtih RT but with non-DEC
> >> drivers for terminal and storage as a small toteable -11.
> >
> >I'd like to hear more about this...
>
> I have a lot on paper plus the ever important T-11 manual.

Very handy.

>  However
> it has stopped at that phase mostly due to other projects having
> my interest.

Fair enough.  I think most of us have a variety of projects cluttering
our foreground task.

> ... only 8KW ram, 8KW Eprom and a DLART for serial IO.

Certainly minimal, though today, 28KW of RAM isn't a stretch.

> The display is really the harder part at least for portability and power
> consumption.  However for this one I was considering packaging along
> the lines of the Kaypro totables and wall power. Part of this recognizes
> the T-11 uses a fair amount of power (Z80 NMOS is similar) and most of
> the parts around it will not be CMOS so battery operation is not easily
> accomplished.

Understandable.

> >As for storage, obviously some flavor of FLASH is great for most
> >things...
>
> None of the above for cost or availability reasons.  I'd opt for IDE
> using one of the many 40-500mb drives I have.

That's certainly a larger device than I'd envisioned (my initial idea
was a "pod" the size of a modem or smaller, with an external
display/keyboard/host port).

> >While textual LCDs are cheaper and easier to interface to, the largest
> >one I've seen is 4x40.  A graphical LCD panel with a SED1335 or t6963
> >of a size of 640x200 would be perfect for 80x25...
>
> I planned on text.  However it's possible to get LCDs used for laptops
> but the logic to drive them is non trivial.

Yes.  I have a 640x400 laptop display, with specs, that ran me about
$10 a few years back.  If I ever decide to learn VHDL, I might try to
interface it to my IOB6120, but, yes, it takes a bit of work to talk
to those.

> >Back to the T-11, though, if I recall its capabilities correctly, it
> >doesn't have an MMU, and it would be difficult, if not impractical, to
> >design an external one that resembles, say, the MMU on an 11/23...
>
> Correct on the OS and software.  However the MMU is very buildable
> and not near as hardware intensive as would seem.  For an example
> look at the T-11 interface in the VT240.  It takes a few 16x4
> bipolar rams and some loose logic to implement the paging (2 74189,
> 3 74ls257 and a bit of TTL glue) to make a a compatable (mostly) mapper.

Interesting.  I suppose it couldn't be _too_ complicated, then, since
it one like it does fit on a few square inches of  11/34 CPU board.

I even happen to have a small pad of 74189s.

> One of the things I've given consideration to in recent years is a nonDEC
> and non *nix OS such as CUBIX as that would translate reasonably from
> 6908 to PDP-11. This arises from the fact that RT-11 has a very
> primitive filesystem compared to CP/M and an OS that is not encumbered
> would be easier to work with.

Hmm... from what I've seen of CUBIX, it sounds feasible for a PDP-11
host, and it certainly gets around the issue of what OS to distribute,
but I would think that porting CUBIX could be an entirely independent
project (focusing on whatever display and mass-storage interfaces are
available).

 > >So, Allison, does any of this sound like what you had in mind... ?
>
> You envision what sould like a Laptop.  I can't easily fabricate that
> but a toteable like Kaypro, Osborne and a few others is very doable.

I hadn't specifically been requiring a laptop shape, more of a tiny
luggable - on the order of one of the modern Tektronix LCD-screen
digital scopes.

> The basic machine description is a 128kW using 32kx8 static parts (8pcs),
> Boot roms/ODT, MMU, two serial, parallel (PC conpatable for printer)
> and IDE disk. Things like OS in Eprom have surfaced to my idea pool
> to consider especially if it were not RT11 (CUBIX influence).  Terminal
> logic would be VK170 (base VT52 on a dual size card) and a monitor in
> the 7-9" size.

OK.  I'm not sure I get the "VK170" reference.  Is that some sort of
DEC or 3rd party embedded product?

Thanks for sharing your design ideas.

-ethan