Re: reading vic20 or c64 column

From: Marko Mäkelä <>
Date: Tue, 30 Jun 2015 10:46:27 +0300
Message-ID: <20150630074627.GB2192@x220>
On Tue, Jun 30, 2015 at 09:18:52AM +0200, Didier Derny wrote:
>Sorry I was not clear, I was speaking of the use of the VIA / CIA to 
>read the keyboard in  VIC20/C64
>Apparently in the code I found  (code for C64) it is writing in the row 
>and reading the column

I seem to remember that the VIC-20 is accessing the keyboard matrix in 
the opposite order.

On a related note, some months ago I played with an Arduino Uno kit with 
my kids. The kit includes a 4×4 key matrix. And guess what, we got the 
same type of shadowing as on the C64 when multiple keys are pressed at 
the same time. And the characteristics differed, depending on which way 
the rows and columns were connected to the ATmega328 pins.

On a practical note, nowadays you would of course use a ‘commodity’ 
input device for your DIY hardware, such as a USB or Bluetooth input 
device or an infra-red remote control unit.

Does anyone know about a semi-scientific writeup on keyboard matrices?


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Received on 2015-06-30 08:01:23

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