This directory contains sound samples of various C64
musics played on a Commodore Plus/4 equipped with a
SID-Card.

There are three variants of each sample:

1) SID 6581R4-Slowclock,  SID6581 is clocked at
   886.72kHz (Mux/2)

2) SID 6581R4-Normalclock,SID6581 is clocked at
   985.24kHz, the same frequency it is clocked at 
   in a real C64. The first two variants were 
   recorded on an experimental SID-card made by me.

3) Sid-Card. This is Christians Schaeffners original
   Card. It is based on a 8580R5 which is clocked at
   886.72kHz (Mux/2) Unfortunately the output ampli-
   fier of the Sid-Card seems to add some distortion,
   however this is almost inaudible without reference.

The SID types do mainly differ by their filter charac-
teristics. This is very apparent in "Example06".

The clockrate influences the pitch and the speed of the 
ADSR envelope, while it has no influence on the song 
speed (this is in sync with the raster) and the filter 
frequency settings. This causes various effects which
lead to audible glitches, apart from the pitch, in 
songs played at different SID clock rates. These effects
are most apparent in "Example14".  

I also added samples of the tune "DWEnd" recorded
on SidPlay2 using the ReSID engine in 6581 and 8580
mode. ReSID is the best SID emulation engine, as of
now. You can find more emulator vs. real sid examples
here: http://gallium.prg.dtu.dk/misc/sid_vs_emu/

Real names of the tunes:

DWend		"Dignified" by Reyn Ouwehand
Example06	"Coma Light VIII,Part11" by 
				Roman Majewski(Compod)
Example14	"Long Distance" by Tomas Danko

The directory "Spice" contains some results of spice 
simulations of the output amplifier circuits used in
the C64A and Solders Sid-Card.

03102004

Contact: referringto@gmail.com