P21h experience (fwd)

[Louis Frazier <cogniscu@xxxxxxx>]

---------- Forwarded message ----------
Date: Sat, 12 Apr 97 23:35:32 -0500
From: louis.frazier@hamptons.com
To: cogniscu@tmn.com
Subject: P21h experience


Some happy observations about Dr. Ting's MuP21h latest assembled processor 
board.

I have run mine for more than 100 hours at 5.6 volts. I found I couldn't
make it work at 5 volts, so I took an old regulated supply and soldered in
an LM317 regulator, a variable 5k and two fixed resistors following a
ham diagram and use it to adjust the 12 volts dc of the old 5 volt supply.
The DRAM memory gets pretty hot, but since it is down to $35 I'll run it
until it smokes before I fool around with trying to run it at 5 and the
p21 at 5-7.

I've been running on an old apple green monitor, and it is all I need for 
geometry. Hwever, when I try to run on a color TV with monitor inputs I 
only get B&W. Before I go to a lot of expense to get an ntsc monitor, I'd 
like to be sure the color is worth it. Can I get satisfactory results by 
using a converter from NTSC to channel 2 or 3?  I think camcorders work that
way.

The display is pretty jumpy, and I don't see any difference when I run T's
routine to slow the I/O.

I have figured out how to run the metacompiler and as soon as I get an
application running that doesn't need much I/O, I'll try to cut polling back
to every second or so from the application program, just enough to get 
it's attention so it can switch back to standard I/O when I want to break in.

I would like to switch screens by programming video jumps, but this whole
area is hard to follow.

   I noted here someplace that Vertical bars and Horizontal retrace
   words are in separate loctions. Is there a memory map somewhere?

   Are there words in Eforth that write valid video jump instructions,
   properly xord?

   Is there any way to follow the jumps in debugging mode?

I draw on the PC screen using Ghostscript, a public domain version of
Postscript. I see the possibility of developing postscript-like functions
to draw on the P21 monitor.

   Has anyone done this, and is the code available?

   If not, where can I find floating point and trig functions in Forth,
   free, which will run in eForth on P21.

Finally, I find Ting's programming environment to be great. Having built
embedded forth on NEC V25's (Ting says embedding's the highest level of
computing!) and having to inprovise all the utilitiies
to upload, download, compile etc., I've never found it easy. His package
lets me do what I want to do, develop applications, in this case
interactive artworks, much faster, and I still am a terrible amateur at
FORTH, and most other languages I've used. I only learn what I have a need
to know.

I could use some documentation of the assembler. It looks like greek to me.

Any comments or suggestions welcome. Especially from people working with
the same board at a higher skill level.

See my work at http://www.artswire.org:70/1/COGNISCU