Re: VIC-registers

From: Marko Mäkelä (
Date: 1998-02-24 01:40:29

Ruud wrote:

> 1) What happens if you write to or read from registers > 46 ($2E)? Are
> there any (undocumented) side-effects which could harm the c64 in any
> way? 

The VIC-II will return $FF on read, and write has no effect.  But note
that the VIC-IIe has two extra registers, one (I think 3-bit) output port
at $d02f and a 2MHz mode/test mode selection register at $d030.  The $d030
register must be initialized with $fc for normal operation.  Also, I've
understood that the SuperCPU accelerator card misuses these addresses for

> 2) Are there PRGs around using the mirror addresses of the VIC,
> $D040-$D3FF? 

Yes, but they shouldn't be very common.


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