8051 vs. 68K

[Magnus Danielson]

> >You should also consider ease of debugging.  The normal way to debug 8051
> >code is with an in-circuit emulator.  With the 68K you can use the GNU
> >debugger and do source level debugging over an RS-232 line.
> 
> Call me "not normal" then.  Europa is being debugged by sending 1 byte
> messages out MIDI....

Well, that's what you used as a serial output...

> t 04:31 PM 11/15/96 +0100, Matthew S. Padden wrote:
> 
> >Just to stick my oar in; all the ideas we've had about programmers are 
> >great, but there's a niggling little worry in my mind which won't go away. I 
> >think it's basically to do with the zipper noise that was discussed 
> >previously; so many synths I've used (digitally-controlled analogue AND 
> >digital) have audible side effects of using 8-bit controls. The filter 
> >cutoff is a good example; generally things at higher pitches seem to suffer 
> >more (Just try quick pitch bending over an octave at the top of the keyboard 
> >on a digital synth). Continuous (ie analogue) controls seem to have far more 
> >purity, again particularly at high pitches. I know that 12 or 16 bit control 
> >is going to be more expensive in terms of cost and implementation, but it 
> >would make a LARGE difference to the sound quality of the system as a whole.
> >
> >	Maybe I'm wrong and I'm getting confused between resolution and realtime 
> >response of the uP... Still, as we're designing it, we might as well try it!
> 
> 12 and 16 bit ADCs/DACs once cost hundreds of dollars.  They just aren't
> that expensive anymore - only a few bucks more than an 8 bit.  Don't be
> stupid, go for higher res.

I am certainly in favour of a higher res solution. We are after all getting
32 channels out of that chip.... if sticking to the original proposal...

> At 05:47 PM 11/15/96 +0100, Magnus Danielson wrote:
> 
> >Besides, for doing just the CV storage things with no extreme things I can do
> >the assembly by hand, just like in the old days.
> 
> To quote Monty Python - YOU'RE LOONY!

Yeap!

> I think I can supply C source for a decent 8051 assembler (Neil fixed it so
> it will even tell you what line a forward reference falls on).  

Certainly would an assembler or even a C compiler be prefered, but that was not
my original point. My point was that a simple CV storage thing would not 
require
that many assembly lines so it could be throw together quite quickly...

> >This way you will not depend
> >on some software tool that only runs under a distinguished system (no names) :)
> 
> C source means you can compile it for whatever distinguished system you prefer.

Totally of my original point, but I agree with your statement.

> >>>   OTOH, half of the group seems inclined towards the 8051 line. If this
> >>   thing can run a Jupiter I'm sure it can do what we're trying to do. If
> >>   poeple who can actually do the design are more comfortable with this IC,
> >>   then that's probably where we should stay. I believe this chip is used in
> >>   my Fatman - yes? It's probably a cheaper and simpler alternative.
> >
> >Well, the 68000 line was probably my idea (or fault :) but I have no trouble
> >with any of them. I think that there is about the same trouble with both CPUs
> >even if the 68000 may be a little too much for just a CV storage unit.
> 
> I agree - it's pretty much a tossup.

Yeap.

> >For this specific project would much out of the 8051 features be unused anyhow.
> >Maybe only the timer/interrupt would be the extra that isn't really in the
> >68000. The timer/interrupt would be used to generate timely interrupts to 
> >preform steady read/updates in a strictly timed fasion.
> >The 8051 also has some onboard RAM, but since we probably have enougth SRAM 
> >outside anyway we migth use some of that to do the same work for the 68000
> >solution.
> 
> 128/256 bytes isn't a lot...

No. It was just to be really picky so people would see the difference...

> >The 8051 can do MIDI really easy with just initiate a few registers properly
> >and have the standard CMOS/TTL to MIDI level conversion. An 68000 would need a
> >external serial chip (like a 6850) do to similar things.
> 
> Right - just look at the JP6 schematic for an example interface.
> 
> Just remember - you DON'T want a CPU w/ built-in EPROM for development.
> It's better to have a dozen cheap, fast EPROMs on hand so you can burn 'em
> and cook 'em quickly...

I agree with this. More people can burn a EPROM rigth away then burn a 8751.

Magnus