MIDI controlled SID, was flying faders, was [sdiy] keyboard resources

[John L Marshall]

No! I was thinking of taking a Commodore 64 and stripping away all of the
unnecessary junk. Throw out the tube, the tape, the disk, the keyboard, all
that stuff. Use the C64 as a SBC. Reprogram it with your favorite language.
It's got 64K of RAM, plenty. There are three ROM's; two 2764's (2364A) and a
2732 (2332A). Chomp the ROM's out and install sockets. There is lots of I/O.
Use the cassette interface with opto-isolator for MIDI. There are two 5626
interface chips for all of the controls that you would ever want to add.

You could use rotary digital encoders for input and a serial LCD panel for
output.

 I suppose that the address lines could be lifted and an address buffer
could be added without too much pain. Keeping digital signals separate from
analog signals is necessary. Use a "common point ground".

I once built a synthesizer using Walsh functions. Talk about noise. Keep the
digital separate from the analog.

By the way, somewhere I have a resistor coefficient table for summing Walsh
values to the sine wave harmonic series. I will dig it up if someone is
interested.


----- Original Message -----
From: Luc Van Den Bosch <luc.ky at pandora.be>
To: John L Marshall <john.l.marshall at gte.net>; <synth-diy at dropmix.xs4all.nl>
Sent: Tuesday, August 28, 2001 1:00 PM
Subject: Re: MIDI controlled SID, was flying faders, was [sdiy] keyboard
resources


> But .... the C64 has a VERY noisy output which makes it unusable in a
> musicians setup.
> I did once (about 10 years ago or so) use the C64 for making sounds, wrote
> some assembler code to play the SID from the C64 keyboard, i know what I'm
> talking about.
> Even connecting the ground of the C64's audio output to my mixer system
put
> the digital noise on top of the output of the mixer.
> That's imho why everyone (including me) is building a dedicated single
board
> computer to control it.
> The SID station for instance uses latches on the adress-bus of the SID to
> minimise adress-bus noise bleeding to the SID's output while the
> microprocessor is adressing some other stuff (like keyboard, display).
> Another good reason might be that the C64 with it's disk drive and
> CRT-display is a rather ponderous thing to move to a gig.
>
> Luc
>
> ----- Original Message -----
> From: John L Marshall <john.l.marshall at gte.net>
> To: <synth-diy at dropmix.xs4all.nl>
> Sent: Tuesday, August 28, 2001 8:58 PM
> Subject: Re: MIDI controlled SID, was flying faders, was [sdiy] keyboard
> resources
>
>
> > The "Commodore 64 Programmer's Reference Guide" has 25 pages dedicated
to
> > the 6581SID.
> >
> > I am unclear as to why people are building dedicated single board
> computers
> > to control the SID. A single board computer already exists with plenty
of
> > RAM, ROM and I/O. The processor is a popular but mature 8 bit type and
it
> is
> > easy to program. This single board has enough speed and power to program
> the
> > 6581 in realtime.The addition of MIDI I/O has already been done. I'm
> talking
> > about the Commodore 64. Cheap and plentiful.
> >
> >
> > ----- Original Message -----
> > From: John Lamb <jlamb3 at nc.rr.com>
> > To: <synth-diy at dropmix.xs4all.nl>
> > Sent: Tuesday, August 28, 2001 12:53 PM
> > Subject: Re: MIDI controlled SID, was flying faders, was [sdiy] keyboard
> > resources
> >
> >
> > > "Andrew Martens" <amartens at interchange.ubc.ca> wrote on 8/27/01
9:42:19
> > PM:
> > >
> > > >That reminds me, I need to get to work on my SID synth again...
> > > >
> > > >Cheers,
> > > >Andrew Martens
> > >
> > > I'm interested in doing something similar -- If you could point me
> towards
> > some good 6581 documentation I
> > > would be much obliged.
> > >
> > > Thanks
> > > John Lamb
> > >
> >
>
>