On Thu, Feb 6, 2014 at 5:15 PM, Kyle Owen <kylevowen at gmail.com> wrote:
On Thu, Feb 6, 2014 at 1:50 PM, Ethan Dicks
<ethan.dicks at gmail.com> wrote:
I recommend using that real serial port for the connection to the
PDP-8. You could ssh into the R-Pi for control or, for a follow-on
product, it's not hard to stick a textual LCD and a couple of buttons
onto the GPIO header. You can even get them as a pre-assembled
shield.
My plan was to use a USB-serial converter for the disk server, a glass
terminal (not the RPi) for TTY: (or another laptop, to make file transfers
easy), and a USB thumb drive to store the data on. Is this what you're
thinking too?
I'm not sure we are talking about exactly the same thing.
What I was thinking about starts with an already-working PDP-8 setup.
One with a dumb terminal on it. It could either use a corner of its
SD card for disk image storage or a USB stick - that part isn't
relevant to how it works (it just affects how tightly coupled storage
is from operational software). There is already a serial port on the
R-Pi that doesn't use the same I/O channel as the USB interface, so
use _that_ for the disk server. If you want to talk to the R-Pi for
control or other functions, use a USB dongle there because the amount
of traffic is small and the USB overhead won't matter. For headless
operations, it's not difficult to put a textual LCD and navigation
buttons (to select and change the media presented to the PDP-8), and
it's not really much more expensive to put a graphical (NTSC) LCD on a
Pi - they come in 7" sizes for backup cameras and such.
Thinking back to TU-58 emulators, you just want a way to "switch
disks" - that can be done by interacting with the R-Pi on its own
console, via ssh or other remote protocol from a nearby PC, or by
directly-attached switches and textual output. It kind of depends on
how physically small you want to make the device and what sort of
physical UI you might prefer.
Were you saying that utilities like tcpser to link the
RPi to another
machine running the server would not be a good idea?
I had no comment about that sort of arrangement.
... as of two days ago, an STM32F4DISCOVERY...
That looks interesting on the surface, and certainly cheap enough, but
what's the longevity? One advantage of using established tech
(Arduino/Sanguino/MEGA...) is the expectation that you'll be able to
find one in five years without having to reengineer the project for
whatever is running around by then. We are talking about a storage
emulator for a 1960s or 1970s computer where longevity is kind of the
point.
-ethan