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| From: TLC (all posts)
Date: 2000-01-18
Subject: Re: SID with Plus4
|
Hi!
> I need some info about the SID card for the Plus4. Whers are the
> registers in the memory? Are there more SID card types?
> Thanks!
The baseaddress is $fd40 and $fe80 (this is because some older prototypes used $fe80, and Solder wanted his card to be compatible with them).
Speaking of the registermap, it's exctly the same as found in the C64
(thus you can use all registers, even the POTX/POTY and the volume envelope read / waveform read regs).
The card runs from the Plus/4 single clock (885Khz), in opposition to the C64 where it runs at 985Khz (PAL). That causes about one note difference. (All original C64 SID musics play lower about one note when played on a Plus/4 SID card). The ADSR speeds are also slower, by exactly the same reason.
The original card also features a joystick port found at baseadd+$1f.
There are some other, rather 'analog' features that make the card sound different to the C64 SID. But I think these don't count in this stage of the emulation (filter setup + DC distortion).
L.
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