3 Jan
2013
3 Jan
'13
8:06 p.m.
On Wed, Jan 2, 2013 at 9:18 PM, Michael Thompson
<michael.99.thompson at gmail.com> wrote:
With lots of help from members of this forum and other
friends I made
a high-speed paper tape reader emulator from a wire-wrapped interface
board and an Emcraft SmartFusion FPGA evaluation board.
Nice.
The interface board plugs onto the Posibus interface
slots in a PDP-8/L.
The PDP-8/L (and PDP-8/i) has slots for a PC8L (or PC8I). While I
applaud anyone who gets a Posibus peripheral working, I wouldn't have
thought that you could have just tapped into the slots for the PC8L
directly at TTL levels (no open collector bus fiddling).
I will make an expanded version of the interface board
and change to
the Emcraft SOM FPGA board. That will give me enough I/O pins to
emulate just about any peripheral that you can connect to the Posibus.
That's far more useful than just a papertape emulator.
Vince can probably tell you that I've wanted an "RX8L" for some time.
I have a PDP-8/L with 12K (via BM08L expansion cabinet) on which I've
wanted to run OS/8 for 25 years but have never had mass storage for.
Adding an RX01 to a PDP-8/L seemed to be the "simplest" solution at
one point.
It would be possible to make an interface board for
the Negibus so
that the peripheral emulator could be used on earlier PDP-8 systems.
That would also be useful - I have a PDP-8/i that I'd love to get
above 4K that I'd also love to run OS/8 on but I figured that the -8/L
would happen first since it already had enough core.
-ethan