Re: reading vic20 or c64 column

From: Didier Derny <>
Date: Mon, 6 Jul 2015 10:38:03 +0200
Message-ID: <>

I was trying to detect the beginning of the scanning (the idea was to 
use that to send "strings" bound on some PC function keys)
apparently its seems useless for the rest I used the classical method of 
the analog switch so the keyboard should be seen as commodore keyboard
the main idea in my project:
  to use either a windows application to control from a PC keboard
or a usb keyboard connected ta small box
and being able to connect to one machine among several

I'm waiting for 3 boards from oshpark...


On 06/07/2015 10:13, smf wrote:
> Making assumptions about how one piece of code (the kernal) reads the 
> keyboard will introduce incompatibilites.
> For example it's possible to enable all rows or all columns and then 
> poll to see if any key is pressed (the commodore LCD rom actually does 
> this).
> Inactive outputs and inputs are essentially the same as far as the 
> keyboard is concerned, you need to look for rows and columns being 
> active and then update your outputs. With the usb keyboard being 
> scanned constantly and a virtual matrix built up.
> Early games especially would be fooled into thinking you've pressed 
> fire on joystick port 2 if you hold space and m. I can't remember the 
> other combinations for the directions (I have a feeling not all of 
> them could be reproduced but I might be wrong). It was useful when a 
> shop loaded up a game but took the joystick away to prevent kids 
> hanging round playing all day. I think this effect might occur even 
> when the keyboard isn't being scanned.
> You can also differentiate between shift and shift lock by programming 
> the cia differently (no idea how reliable or common that is).
> *Sent:* Tuesday, June 30, 2015 at 9:07 AM
> *From:* "Didier Derny" <>
> *To:*
> *Subject:* Re: reading vic20 or c64 column
> I'm working on usb/bluetooth keyboard for several machines
> I wanted to detect when the commodore is starting to scan the keyboard
> Message was sent through the cbm-hackers mailing list 

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Received on 2015-07-06 09:02:29

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