Ethan Dicks wrote:
On Mon, Oct 22, 2018 at 10:39 PM Carlos E Murillo-Sanchez via cctalk
<cctalk@classiccmp.org> wrote:
you. The thing
is, I would like to have something pdp8-ish that would allow me to play
a little bit
with the programming languages that were available for these machines,
FORTRAN 4K and
FORTRAN IV in particular. Now, I would love to be able to time some
FORTRAN jobs just
to get an idea about what it was like back then. I am aware of PiDP-8,
simh, as well as
SBC6120, SBC6120RBC.
I would probably do all the things but in a particular order.
If my goal was to learn PDP-8 software, I would just start with simh
running on anything. I have a PiDP-8. It's nice. You definitely get
the feel of running an older PDP-8 (except no noise for floppy drives
or DECtape, and no seek time) but under the blinky covers, it's
running simh. You can learn everything about the configuration of
PDP-8 models, about memory, and all the programming languages with
simh. From there, consider a PiDP-8 if you want a quick junior-sized
emulated machine for the look and feel of things.
The SBC6120 with FB6120 is also nice. I have one.
-snip-
Based on the answers from everyone (Thanks!), I think that I will grab
one of the RaspberryPi's laying around and start using the PiDP-8
software or plain simH while I can procure the hardware side of PiDP-8;
I think that I'll perform the serial console hack on the Pi. I will
continue to research options for programming the GALs in the SBC6120 or
SBC6120RBC, since I have one HD6120 chip and it would be a waste not to
use it. The OSI Processor Lab route seems interesting, especially since
I have three HM6100 chips, but I think that it isn't in a stage that
allows reproducing the PDP-8 usage experience.
If you guys can recommend a cheap programmer that handles the
ATF22V10CQZ-20PU and ATF16V8BQL-15PU (SBC6120) without problems, I am
all ears.
>From there, one of the challenges of repairing your VT78 and VT278
boards is there's no blinkenlights console to assess repair status
during the repair or to try to toggle in test programs. Replacing a
ROM is easy enough, even if you have to make a pin-swapping socket
adapter to use a modern EPROM (I don't know what type of ROM is in the
VT78, but it's possible that it's something standard like a 2708 or
2716).
-ethan
The control panel ROM in the vt78 is proprietary (12bit data width), so
it would have to be replaced by a more complex circuit. But one of the
three vt78s that I have does have that chip, so this is an issue only if
I try to restore the other two boards.
Carlos.
