Re: VIC-II initialization.

From: Segher Boessenkool <segher_at_kernel.crashing.org>
Date: Mon, 31 May 2021 11:11:45 -0500
Message-ID: <20210531161145.GG3085_at_gate.crashing.org>
On Sun, May 30, 2021 at 11:52:13AM +0200, groepaz_at_gmx.net wrote:
> Am Sonntag, 30. Mai 2021, 01:29:05 CEST schrieb Segher Boessenkool:
> > On Sat, May 29, 2021 at 09:56:13PM +0200, Michiel Boland wrote:
> > > I believe all registers in the VIC chip are initially zero,
> >
> > They are not.  Usually you get what was there before reset.  At actual
> > power-up time you get random values: there is nothing that forces it any
> > certain way, although it may usually go one way in practice.
> 
> zero at powerup seems pretty much the norm in practise :)

Yes, but there is nothing that forces it, and not even asymmetric
inverter loops to nudge things one way or the other.  The most important
thing to notice is there is nothing connected to the reset input (there
*is* no reset input :-) )

Many things will work out after one or two frames, including all
internal state, but the registers will have to be set (if you care about
their value at all).


Segher
Received on 2021-05-31 19:00:05

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