Hey Peter,
I think this is what Mike (the creator of the Hawk800) was intending to do with the idea of adding some encoder dials to the Poly800.
Couldnt there be a way to use a multiplexer/de-multiplexer to allow more than 4 knobs?
Isnt that what Korg did to cram an entire set of playing keys(switches) on the keyboard AND all the panel switches to be scanned by the 8 pins on the 80C85A CPU?
Refer to section 21 in the P800 schematics.. I think there you will find that both the keyboard and the panel switches all merge into a demultiplexer.. then are converted to a bit code that is dumped onto the bus... AD0-AD7 (pins 12-19 on the CPU).
I read that there is a 3-to-8 demultiplexer on board (TC-40H138).. doesnt that mean three 8bit streams are from mostly the keyboard and the panel switch matrix's and used to share the CPU's data bus?
Couldnt the circuit be modded to integrate more 8bit streams?
I could be wrong.. lol. I understand very little about digital electronics, obviously.
Another idea I had was to somehow have 4-6 knobs and with a momentary switch of sorts, make the knobs change from one series of controllers to another.
Say in one scene, the dials will control VCF parameters, then punch a button and the dials turn into Envelope Generator dials (preferably six for the "break point" and "slope" parameters of the EG). Punch it again and it becomes Depth control of each of the four LFO's... not necessarily in that order, but you get the idea.
Keep in mind that the encoders can have a momentary switch on each of them.. push the knob/dial down and it activates a change..
There could be a simple series of LED's nearby to indicate what "scene" the knobs are in.. or use the encoders with LED's built into the encoder.. so when you switch scenes, the color of the knob changes! :)
You could even make the LED knobs be steady on, blink slowly, blink quickly.. and of course change colors.. heck, lets make them blink red, green, red, green... lol.
I wish I could offer more assistance in this mod, but I admit I know little to none of digital circuits and assy. code. That's where Mike would come in with all his custom code already in place.
Chances are that many of the subroutines that these new dials would need may already be there in use by the extra MIDI access coding he's done.. he'd simply just need to point to those subroutines already in ROM.
I really dont have any idea how much memory Mike has left to add in more features. I would think that 64K wouldnt all have been used up yet. Back in 1983, that was ALOT of memory for a home PC. I thought it was amazing when the Commodore 64 came out with it's 64K and all the fun things it did back then.
Cheers
-Blaine
--- In korgpolyex@yahoogroups.com, Ullrich Peter <peter.ullrich@...> wrote:
>
> Hi Blaine!
>
> If you are in the situation that you can change the source code then you have more features of course.
> I bet that it would be possible to add some encoders for interesting parameters if there is enough space in the eprom.
> In this case you can maybe complete bypass the keyboard matrix and could add maybe an 8 bit port for 4
> encoders on a free I/O address and the software does the encoding and parameter changes.
>
> In theory it would be possible but its work that has to be done, and of course some tesing.
>
> Ciao
> Peter
>