--- Tony Duell <ard_at_p850ug1.demon.co.uk> wrote:
> > If you are going to do that, why not use a DEC CPU?
>
> I thought about suggesting that, but the hardware hacker in me wants to
> keep it as simple as possible :-)
I understand. I'm both a software and a hardware hacker, so I don't mind
moving the set-point over a bit for a combination solution.
> I think I could make a Unibus master and arbiter in a handful of TTL
> chips (look at the releveant bits of a Unibus CPU printset -- it's not
> that complicated). Using a CPU sounds like overkill..
Overkill from one sense, but it depends on how elaborate you'd want
it to be.
> There's also the issue that I wanted to keep stuff 'out of the way' I was
> thinking it would be useful if the new host could do _anything_ to the
> disk controller (that's one good reason to avoidthe BSD device drivers,
> actually).
True.
> > Why not just use a PDP-11/53 CPU board with local serial and on-board
>
> I don;t have one :-)
Good reason. :-)
> Anyway, I'm more of a Unibus person...
Fair enough. I do both (plus VAXBI) since I used to make all of that
kind of stuff for a living. Personally, I have a lot of experience with
Qbus machines because that's what was popular when I began to take over
the hardware department. I still love Unibus stuff, though.
> It's a pity that computers with lots of parallel I/O lines are so
> uncommon, and the user ports are out of fashion now...
No doubt. I did a lot of stuff with the User Port on the PET and C-64
(the Simon clone from Byte, an external big-key keyboard, a 2-digit
7-segment display, a high-speed CBM interconnect, a rudimentary IEEE-488
tracer, etc.)
> One thing I would _love_ to find is a portable-ish machine which can
> write a disk that's readable on a PC, and which has at least 32 parallel
> I/O lines, totally user controllable.
Hmm... you'll laugh... my SBC-6120 w/IOB-6120 fits the bill... the
IOB-6120 has 36 I/O lines that are designatable I, O or Z by PDP-8 IOTs,
and a CF socket, and the base SBC-6120 has an IDE port. The CF cards/disks
do not use a DOS-compatible partition scheme, but can be read/written-to
by DOS utilities. I have a ZIP drive backpack battery that can power it,
or I can drive it from the PS/2 port of my laptop.
You could even modify the FPGA code to make the 36 I/O pins be something
other than plain vanilla I/O lines, if that were necessary for timing
reasons.
I wonder how hard it would be to add an RL8A to the IOB-6120... I better
finish assembling one first, before I start trying to enhance it. :-)
-ethan
Received on Wed Jun 04 2003 - 21:25:01 BST