Vic20 as accordion bass instrument?

Basic and Machine Language

Moderator: Moderators

Post Reply
nippur72
de Lagash
Posts: 574
Joined: Thu Sep 07, 2006 8:35 am

Vic20 as accordion bass instrument?

Post by nippur72 »

I have this crazy idea I would like to discuss with you expert vic20-musicians before going to implement it.

Well the idea is to write a keyboard instrument playing program, but instead of having the notes arranged as in a piano-like keyboard (white and black keys), they should be arranged like in accordion bass:

Image

the program would be used to play the accompaniment part of a song, so it should be able to play chords (Major, minor and 7th).

An example of what I want to realized is this youtube video

Unfortunately I am not an accordion player so I don't know all the details (note values etc) but I think I can sort these details out.

The problem is the sound capability of the Vic20. For example the 7th chord requires four voice channels but Vic has only three. So instead of using plain voice channels I was thinking of implementing single-voice with arpeggiato effect (to understand, the "0" effect in amiga mods). This way it should be possible to play multiple keys pressed simultaneously. But as far as I can remember I haven't seen the arpeggiato effect used in vic20 music (I might be wrong).

So, just give me your suggestions,idea,impressions... is the whole thing doable, worth the effort?
Boray
Musical Smurf
Posts: 4064
Joined: Mon May 03, 2004 10:47 am

Post by Boray »

Apart from the sound limitations, it would be hard to read several keys pressed at the same time, would it not?

(This is me playing accordion by the way: http://boray.bandcamp.com/track/silly-sailor-song )
PRG Starter - a VICE helper / Vic Software (Boray Gammon, SD2IEC music player, Vic Disk Menu, Tribbles, Mega Omega, How Many 8K etc.)
nippur72
de Lagash
Posts: 574
Joined: Thu Sep 07, 2006 8:35 am

Post by nippur72 »

I think keyboard can be read by scanning column and row of the key pressed ($9120 and $9121) so in theory it should be possible to detect more than on key pressed at a time (I guess that's how CTRL or SHIFT works). But never attempted that.

P.S. was it a real accordion, or was it soundfont?
User avatar
RobertBe
Vic 20 Elite
Posts: 2304
Joined: Sat Jul 14, 2007 2:48 pm

Post by RobertBe »

Boray wrote:Apart from the sound limitations, it would be hard to read several keys pressed at the same time, would it not?
Cynthcart for the C64 reads two keys pressed at the same time in order to form musical chords.

Truly,
Robert Bernardo
Fresno Commodore User Group
http://videocam.net.au/fcug
Boray
Musical Smurf
Posts: 4064
Joined: Mon May 03, 2004 10:47 am

Post by Boray »

nippur72 wrote:P.S. was it a real accordion, or was it soundfont?
A real of course. What is soundfront?
PRG Starter - a VICE helper / Vic Software (Boray Gammon, SD2IEC music player, Vic Disk Menu, Tribbles, Mega Omega, How Many 8K etc.)
nippur72
de Lagash
Posts: 574
Joined: Thu Sep 07, 2006 8:35 am

Post by nippur72 »

oh wow, a real accordion. You have my admiration! I thought it was sample-based keyboard playing (aka soundfont).

Here in Italy we have an instrument called organetto (known also as diatonic accordion) that is similar to an accordion but with only diatonic notes on the melody and only major chords on the bass line. But it's rather complex to play because the notes are different depending on the direction of the air flow. Never managed to learn it! But it's very common in italian folk music like in this video.
Boray
Musical Smurf
Posts: 4064
Joined: Mon May 03, 2004 10:47 am

Post by Boray »

I have seen accordions like that here too. Kind of like how an harmonica works.
PRG Starter - a VICE helper / Vic Software (Boray Gammon, SD2IEC music player, Vic Disk Menu, Tribbles, Mega Omega, How Many 8K etc.)
User avatar
Schema
factor
Posts: 1430
Joined: Tue Mar 23, 2004 7:07 am
Website: http://www.jammingsignal.com
Location: Toronto, Ontario

Post by Schema »

Cool idea.
crock
Vic 20 Amateur
Posts: 45
Joined: Sun Dec 26, 2010 1:04 am

Post by crock »

nippur72 wrote:I think keyboard can be read by scanning column and row of the key pressed ($9120 and $9121) so in theory it should be possible to detect more than on key pressed at a time (I guess that's how CTRL or SHIFT works). But never attempted that
You can only reliably decode 2 keys pressed at once. Any more than that and the result is ambiguous because you create unintended pathways through the matrix.

Rob
TBCVIC
Vic 20 Hobbyist
Posts: 127
Joined: Thu Mar 05, 2009 3:38 am

Post by TBCVIC »

crock wrote:
You can only reliably decode 2 keys pressed at once. Any more than that and the result is ambiguous because you create unintended pathways through the matrix.

Rob
Sounds awesome, maybe you can run into the woman in the red dress? :)
Ola Andersson
Image
crock
Vic 20 Amateur
Posts: 45
Joined: Sun Dec 26, 2010 1:04 am

Post by crock »

TBCVIC wrote:Sounds awesome, maybe you can run into the woman in the red dress? :)
lol - that was unintentional... :lol:
nippur72
de Lagash
Posts: 574
Joined: Thu Sep 07, 2006 8:35 am

Post by nippur72 »

crock wrote:You can only reliably decode 2 keys pressed at once. Any more than that and the result is ambiguous because you create unintended pathways through the matrix.
I wonder how much accurate is the VICE emulator in this regard.

I wrote a small keyboard scan matrix program, but I have to test it on a real VIC yet.

Image
crock
Vic 20 Amateur
Posts: 45
Joined: Sun Dec 26, 2010 1:04 am

Post by crock »

nippur72 wrote:I wonder how much accurate is the VICE emulator in this regard.
Not very, but then again it doesn't usually need to. :?

If you hold down 1,2 & 3 in vice - you see this:

Image

But on a real VIC you see this:

Image

The reason is quite simple. Using your diagram, the '1' key is row 1, column 1, '2' is row 1 column 8 and '3' is row 2 column 1.

Assuming it's the columns that are the outputs, when column 8 is polled, row 2 is pulled low through c8-r1,c1-r1,c1-r2.

The screenshot you posted does not highlight the problem because 'R', 'S' and 'V' are do not have any overlap between rows and columns.

Hope this helps,
Rob
nippur72
de Lagash
Posts: 574
Joined: Thu Sep 07, 2006 8:35 am

Post by nippur72 »

very clear, thank you!
TNT
Vic 20 Hobbyist
Posts: 121
Joined: Wed Apr 29, 2009 5:46 am

Post by TNT »

nippur72 wrote:
crock wrote:You can only reliably decode 2 keys pressed at once. Any more than that and the result is ambiguous because you create unintended pathways through the matrix.
I wonder how much accurate is the VICE emulator in this regard.
Emulated result depends on the keyboard as well as the emulator. Some el cheapo keyboard detect only two "normal" keys pressed simultaneously in addition to qualifier keys (shift/alt/ctrl etc).
Post Reply