Setting the SID type in the configuration enables the bus access to the chip, and also allows the
auto-configurator to choose the right chip when playing a SID tune with the provided player from
Wilfred Bos.
Real SID on Board revisions 1.3 (U64 Elite) and 1.4
The newer board revisions are jumperless. This means that both the voltage as well as the filter caps
are selected automatically, based on the inserted SID type. For this, firmware V1.22 or later is
required. Do not downgrade to earlier versions on jumperless boards!
In order to make sure that 8580 chips are never given a higher voltage than they can handle, the
socket gets disabled automatically whenever an 6581 chip (which needs 12V) is detected for the
first time. When the popup appears “SID changed”, enter the configuration menu, and enable the
socket in which the 6581 resides:
Short press on power button
F2
SID Sockets Configuration
Enable the sockets with options:
SID in socket 1
and
SID in socket 2
Once the chip in the socket is recognized as 6581 AND the socket is enabled, the 12V is applied.
Pull Down Resistor
Note that in the original schematics of the C64, a so called “pull-down” resistor of 1 kΩ is placed
from the audio output pin to ground. This resistor is present on the 6581-based boards, but absent
on the 8580-based boards. On the jumperless U64 boards this resistor is also enabled and disabled
automatically. However, you may override this in the same configuration menu. The influence is
limited.
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