8051 vs. 68K

[honcho at paia.com]

>Anyone have or know of "public domain" samples of 8051 MIDI code?  I 
have an HMI 8051 emulator I might dust off and try out sometime and I 
haven't seen much of anything for MIDI out there.
>>>  

Hi Barry and list-

The FatMan and MIDI Drum Brain code on PAiA's web pages is not really 
public domain, in that we would be mightily upset is some manufacturer 
started using this code directly with no modification in a commercial 
product. But, the experimenter that wants to either use it direct, or 
better yet hack it, in a product for their personal use is welcome to 
do so. 

Interesting that this whole debate came up over the last few weeks 
because just before it started, I had inherited coding chores on our 
perpetually imminent midi2cv8. I wanted to contribute then, but was 
just way up over my ears in bits. I've posted the situation on the 
midi>cv as an update to www.paia.com/midi2cv.htm and there's a link 
there to the first cut of the firmware as well. 

Here are some resources that I recommend for those interested in 
checking out the 8031 (which has EPROM on board) and 8051 (External 
ROM) chips. First, the book "The 8051 Microcontroller / Architecture, 
Programming and Applications" by Kenneth J. Ayala. My copy is about 3 
years old, I don't know if it's still published by West Publishing Co, 
50 W. Kellog Blvd. St.Paul,MN 55164. It came with a diskette that had 
an assembler and simulator that runs on a PC. (a very valuable tool, 
simulators, particularly for "groking" the chip in the first place). 
The assembler uses a syntax that's a little different from MCS-51, 
which seems to be sort of industry standard and the simulator is not 
w'95 friendly at all.

There are more elaborate tools available from 
http://www.archimedesinc.com/8051.htm and the demo versions of them 
are quite usable. There's an assembler, C compiler and a much better 
simulator than the one that comes with the book because it allows you 
to easily simulate the ports, serial in/out, and interrupts. The book 
one is really weak on real-time stuff. But the book is at my side 
constantly while writing code. 

I haven't found Intel's appBuilder (some where at www.intel.com) to be 
particularly useful. In fact, for the beginner (like me, when it comes 
to 8051s) it hides a lot of the bit-groveling that's so important to 
really getting a handle on things. 

I've been using an EPROM Emulator from Tech Tools in Dallas (sorry, 
don't have an address). It plugs into a parallel printer port and then 
into the ROM socket of the midi2cv8 and allows of downloading code 
without burning a PROM. The downside of a PROM emulator is that you 
can't see inside the target, to know what's going on in it's little 
pea brain when it gets sooooo lost in space. Wish I had an 
in-circuit-emulator, but the simulator helps and I generally try to 
set up one or more leds on prototype's port lines or other strategic 
places and then insert jumps to traps (there is one in the midi2cv8 
code that blinks leds on the octave select lines) to find out where 
things have gone. Primitive, I know, but we're not programming moon 
shots here.

You can sometimes find surplus 8051s at very reasonable prices (since 
they already have code burned into them - thanks Barry :-). But the 
part has a pin that you yank low to disable onboard PROM and select 
external EEee(whatever)PROM instead, so they're great for the diy-er. 

-John

---------------------------------------------------------
John Simonton                  PAiA Electronics, Inc
3200 Teakwood Ln.              honcho at paia.com
Edmond OK 73013                http://www.paia.com
405-340-6300                   fax 405-340-6378