z80 stuff

[Jason D Stephens]

On Wed, 28 Apr 1999 08:58:13 -0700 (Pacific Daylight Time) Barry L Klein
<Barry.L.Klein at wdc.com> writes:

>Barry Klein:
>
>The Z80 is the microcontroller used to manage things like autotune, 
>
>**How's that?  I've heard of problems with (ie) Moogs having some 
>trouble
>tuning or you'd have to tune every time you turned it on.

>The Minimoog and modular VCO's did not utilize ANY microcontrollers.  

**yeah i knew that....i meant with the design they had.  Maybe temp was a
factor in this?

> Autotune is where 
>the microcontroller
>tunes all voices across the keyboard 1V/octave as well as to each 
>other.

**Saves you that little troube of having to tune it every so often?

 A minimoog is
>only one voice and is manually tuned by a technician and it is hoped 
>to be stable for the
>next several months or so - it depends on stability of contact 
>resistance in the
>connections, the temperature the unit is used in, how long it is on, 
>and variances in
>components.  

**So that's why it couldn't maintain it's tuning?  General
inconsistancies in temp, parts, etc?

>>keyboard scanning,
>The memorymoog has a single contact per key tied to a diode that 

**I've seen diodes in a keyboard layout before....i was wondering about
that....

>brings a pullup resistor

>to 5V down to ground when the key is pressed.  All keys are in like a 
>10 by 10 matrix or
>so that is scanned and any levels at ground are a key down and are so 
>noted in the
>microcontroller's memory. 

**(this may sound dumb) So a key pressed grounds 5V?

>the Z80 has been around for years and continues to be a succesful 
>Zilog product. 
>Newer versions have more on the chip itself so you can make a similar 
>design with less
>parts but cheaper and faster. 

**So you could substitute part of the chip for physical parts?

It doesn't come programmed though - 
>some poor programmer
>guy has to do that!

**I was a fraid you'd say that.....  What does that entail?  I'm guessing
a lot of free time.  How exactly would you program it?  I think i've seen
chip programmers for sale in a catalog or something but i don't know
anything about them.  Could you shed some like on this issue?

I sell a book on Modular synth design, 

**How much?

>written in the same era,
>but I think it is too much electronics for you.

**:-/  Try me....  (give me a little more credit than that!!  :-)   )

Building a modular will teach you a hell of a lot of 
>electronics.  If that's
>not what you want....

**exactly....i was studying to be an electical engineer to start with.  I
wouldn't have started if i didn't thing i could finish.  However, it
wasn't what i wanted to do full time.  That's why i'm studying music now.
 Electronics is a hobby now.  I really want to know more about it.  I
read every message that comes thru the diy mailing list.   I've learned a
lot just from that.  I just try to know EVERYTHING about my hobbies.  I
mean everything-inside and out.  So i ask a lot of questions.  How else
can you press toward knowledge?  ;-)

Jason

PS  Remember, i'm only 20.  I didn't grow up with analog synths.  I have
a lot of catching up to do.  :-)

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