The double characters is most likely how you set up you serial. Normally A Forth will echo
your typing so you want to set it for duplex.
You might look at the locations it uses for things like TIB, return stack and data stack.
I suspect at least the return and data stack may be working but it is also possible your
memory isn't fully decoded and you are over writing your code.
It may not be seeing the right character for a end of line. Most expect a 0Dh and a 0Ah.
check your serial setup for that as well.
Dwight
________________________________
From: cctech <cctech-bounces at classiccmp.org> on behalf of Stephen Pereira via
cctech <cctech at classiccmp.org>
Sent: Saturday, June 23, 2018 12:16:34 PM
To: cctech at
classiccmp.org
Subject: 6800 fig-FORTH?
Hi folks,
I know there's not much 6800 activity here, but I figure this would be worth a try.
Has anyone here ever seen or ever had fig-FORTH for the 6800 working?
I have a SWTPC replica system from Bob Applegate / Corsham Technologies, and I love it. It
came with a complete 64K RAM, as well as the SWIBUG monitor, and the monitor code has been
extended by Bob/Corsham to interface with an SD Card sub-system for floppy disk emulation.
This provides the original terminal access to the machine with the simple system monitor,
and also the FLEX OS for running programs. It is a blast to use.
Recently, I took a look around and found the fig-FORTH listing as originally published
back in 1979, and also a Source Forge site that holds an electronic copy:
https://sourceforge.net/projects/asm...th_6800-stuff/
<https://sourceforge.net/projects/asm68c/files/fig-forth_6800-stuff/>
I've managed to get the source code to assemble with a cross-assembler supplied by
Bob/Corsham. It does not produce an exact copy of the original code, because the code uses
the JMP instruction pretty much exclusively, and the assembler substitutes a relative BRA
instruction sometimes. So my code ends up being several bytes shorter because of saving
one byte each time a JMP is replaced by a BRA. That said, it appears to me that the code
matches up with the original listing otherwise.
So my problem is this: When I run the code on my system, fig-FORTH seems to sign on, and
will accept input from the keyboard (double echos of each key typed) but it then does not
proceed to interpret the command entered. The interesting thing I see by winding my way
around in the code is that it has already properly performed a bunch of setup and produces
the initial "Forth-68" sign on, and that has required it to already be using
many of the Forth commands that were defined by machine language. This indicates to me
that some of the command interpretation is working. The I/O from/to the terminal is by
calls to the system monitor I/O routines, and that seems to be also working, despite the
double echos of the typed characters. It just does not proceed to interpret what is typed
in at all.
Of course, I have no idea if this code ever worked properly, or if I am encountering early
buggy code. So I'm looking to see if anyone else has ever seen the fig-FORTH working
on a 6800 system? Any pointers to good working code?
Thanks for listening!
smp
- - -
Stephen Pereira
Bedford, NH 03110
KB1SXE