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| From: Peter Trauner
Date: 2001-05-06
Subject: Re: Question about SIDCARD schematics/ports
|
"Hársfalvi, Levente" wrote:
>
> Hi!
>
> Peter Trauner írta:
> >
> > Hallo,
> >
> > does somebody know the exact behaviour of the
> > sidcard's IO or have the schematics handy.
>
> There's a GAL (or PAL for the earlier versions) on the card for address
> decoding.
>
> The SID maps to both $fd40 and $fe80, otherwise nothing special. Also, IIRC
> there is a 74LS245 that is used as joystick port, its CS is also generated
> by the GAL somehow (the base address must be somewhere at the end of the SID
> register map, maybe base+$1f? I don't remember).
My impressions:
when I added sid emulation at 0xfd40 only a few programs had sid sound.
with additional 0xd400 writes, a lot of programs and intros have sid sound,
but I have problem with noise, so I assume the sidcard is not always mapped to 0xd400 (maybe it uses some of the rom chip select lines, or an flipflop (maybe in the PAL/GAL)).
Added 0xfe80 and disabled 0xd400:
a lot of programs now do not have sid sound again.
Do you, or somebody else know the exact function of the gal, or is able to read it out?
Do the sidcard have separate sound outputs?
And was the ted sound hearable over these separate output?
There was also a joystick port on the sidcard!?
Maybe to allow an additional standard c64 joystick with dsub9 connector?
Or to allow use of the vc20/c64 paddles?
Were there some programs relying on the joystick/paddles?
> As to the sch, I guess the author (Christian Schäffner) has never published
> it.
Did all the sidcard users buy boards/gals or complete sidcards?
Thanks,
Peter T.
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