Advice needed: Entry point into things PDP-8

[systems_glitch]

There's also our Ohio Scientific 560Z "Processor Lab" reproduction:

http://www.glitchwrks.com/2017/02/26/osi-560z-build

It uses the Intersil IM6100 and executes PDP-8 code. Memory management is
implemented in handlers written in 6502 assembly on the host system, so you
can have whatever memory management you like. I believe one of the guys on
the osiweb.org forums has PDP-8/e memory management working. I don't know
if he has OS/8 running yet, but does have at least FOCAL going. You of
course need a 12-bit memory board, which we also make (uses modern
components, works with FeRAM for a core-like experience). And you'll need
some sort of host system, the simplest being an Ohio Scientific 502 at the
moment (basically a single-board 6502 system with serial console).

That's probably the cheapest/most reliable *non-emulation* route. Of
course, emulation is going to be both cheaper and more reliable.

Thanks,
Jonathan

On Tue, Oct 23, 2018 at 12:17 AM Paul Anderson via cctalk <
cctalk at classiccmp.org> wrote:

> Hi Carlos,
>
> With the cost of PDP-8 parts and the need for maintenance and repair, if
> you can find an emulator that will do what you want, go for it.
>
> Paul
>
> On Mon, Oct 22, 2018 at 10:39 PM Carlos E Murillo-Sanchez via cctalk <
> cctalk at classiccmp.org> wrote:
>
> > Greetings all...
> >
> > I have been pondering something and would love to receive feedback from
> > 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 happen to have three VT78 cpu boards (sans the RAM board) and two
> > vt278 cpu boards.
> > All were in rather sorry condition; I picked them up from a junk pile
> > that was stacked
> > several feet high and in which the contents were mostly random. Thus,
> > the VT78 boards'
> > components were scratched and in fact two of them are missing the
> > control panel ROM chip.
> > Otherwise they are complete, but I am missing the RAM boards.  The VT278
> > boards
> > were further abused by someone who yanked out the oscillators and a few
> > TTL chips,
> > damaging several traces, which I have now repaired.  Alas, only one of
> > them has the
> > HM6120 cpu chip, and I do not know if it is good or not. Both are
> > missing the SMC5037
> > CRT generator chip.  Other than that, they are complete.
> >
> > So, now that we all know what I have, let me say out loud what I've been
> > thinking:
> >
> > If I try to build actual hardware:
> >
> > I've read that the VT278 has serious software compatibility issues with
> > older software
> > due to the use of the HM6121 I/O chip.  So even if I get an adequate
> > keyboard, buy the
> > CRT chip and manage to use it to drive a monitor, I would need an
> > original floppy drive
> > system and media, because I do not have the DP278 serial comms board
> > that would allow me
> > to send the VT278 a program to run;
> >
> > For the VT78, I would need to hack a memory board, and, since it can be
> > coaxed to accept
> > a program to run if it is fooled into thinking that it is loading a
> > program from an
> > MR78/paper tape, perhaps I could make it boot something.  I would need
> > to wire-up
> > and arduino or something like it to translate the keyboard and display
> > terminal
> > chatter in the serial console into something usable.  But, that's three
> > hardware
> > projects (memory board, MR78-like contraption, microcontrolled serial
> > console
> > translator)...
> >
> > The last hardware option is to go and make an SBC6120RBC;  I would need
> > to buy
> > programmers for the GAL/PAL devices, and I've heard that not all
> > programmers can deal
> > with the kind of chips used in it.  And, if it turns out that the HM6120
> > chip that I
> > have is bad, I would have to hunt down one of those rare beasts.. It
> > would be awesome, though,
> > to have an SBC6120RBC up and running, and be able to time actual
> > hardware running
> > FORTRAN.
> >
> > And then comes the emulation option, with the PiDP-8.  I have to say
> > that the emulation
> > of the blinkenlights is very, very attractive to me, and this option is
> > a no-brainer
> > hardware-wise.
> >
> > So...  am I missing something in my estimation of the effort involved in
> > these options?
> >
> > What would _you_ do?
> >
> > Carlos.
> >
> >
>