Subject: Re: A2000-040 and Picasso II
To: Andrew Cherry" , "amiga <amiga@NetBSD.ORG>
From: Markus Illenseer <email@example.com>
Date: 03/13/1995 10:46:08
Andrew Cherry wrote:
> Oh, also, the kernel boots up properly and the Picasso II is recognized.
> The problem only happens when an attempt is made to open a Picasso
> screen (i.e. start Xamiga24). It switches to the Picasso and opens
> up a screen with the correct size and refresh rates, but the screen
> is black. At least I assume the screen is the right size;
> it's hard to tell with a black screen. I do know that the refresh
> rates are correct, though, since my monitor displays that information,
> so it's not a case of the monitor blanking out because the frequencies
> are out of range.
The black screen means that the Picasso is not correctly intialized
at all! The problem is known, I have tried to fix it using the hack
which added a 0xfff to the register-addresses hoping that the
040-Interface would then magically use the correct registers, alas it
The white-screen-bug - which you don't encounter - was due to
too-fast-accesses to the registers in some 040 or even fast 030
environments, this could be surrounded with some NOPs.
I know the bug is only imminent for A2000 with 2 specific 040 boards:
Firecracker and GVP. Both are known to have a buggy 040 interface,
under ADOS you would correct it using (a special) setpatch.