PDP8 and Z-machine engine

[Johnny Billquist]

Christian Corti <cc at corti-net.de> skrev:

On Sun, 3 Sep 2006, Johnny Billquist wrote:
 > > > No, you'd just have to write it from scratch. Nothing strange 
about that, and
 > > > doing something about V4 and V5 games isn't that difficult 
either. Given a
 > > > little time I sure could whip one together, but for now I'll 
leave the
 > > > exercise to someone else.
 > > > I've already written one Z-machine interpreter in MACRO-11. It 
deals with
 > > > anything V1 to V8, except for obvious limitations (no sounds, no 
graphics, no
 > > > mouse...)
 >
 > There I completely disagree! I've ported the Z-machine interpreter from
 > InterTaskForce (written in C, and really good if you want to understand
 > how the interpreter works) to the IBM 5110 (written in PALM assembler),
 > including paging etc. But until now nobody else has ever wanted to 
try it
 > on his 5110/5120... Seems all 5110 owners don't want to use their
machines.

:-)
However, have you ever programmed on a PDP-8?
If so, you would realize that it really requires you to do things a bit 
different from what people nowadays do.
You have 4K word pages. One word is 12 bits. The addressing style of 
instructions really limit most routines to what you can fit into 128 
words. No stack...
Well, there are a lot of things to play around with.
Like I said, it wouldn't be difficult to write a Z-machine interpreter 
for the PDP-8, but you'd better not base it on something written in C.
You might pick an idea or two from Frotz, for instance, but you'd have 
to rewrite that as well to fit with the PDP-8.
And you have almost no OS to support you either, so you'd have to 
implement the I/O as well, and figure out which, if any, clock you have, 
if you want to implement timed input.

	Johnny