5.5
Mono Controller Multiplexer
When mono controllers are selected in the MOD BANKS, the CPU loads
the respective cell in the LS670 4x4 dual port RAMs. The outputs of
these RAMs are constantly scanned by the mod system and switch the
controllers on or off via the CD4016 analog switch U3. This forms a
“multiplexed mixer” with U1 and U2 LF356 high speed opamps. The
output of this multiplexed mixer is routed to the ANAMOD 2 card for
demultiplexing into eight signals that contain the summed mono
controllers for banks A-D for the Left and Right sides of the modulation
system.
5.6
Miscellaneous Switching Functions
The two CD4174 addressable latches are used by the CPU to address
the POT PANEL parameter trimmers. See the POT PANEL theory for an
explanation of how these trimmers are accessed. The CPU controls
these latches via the level-shifted 15V address bus and data line D715.
Note that a CD4053 triple switch is used to select either the parameter
trimmer addresses PA0-PA7 or the mod system scan lines MA1 & MA2.
The outputs are called VMA0, VMA1 & VMA2, and are used to address
the CD4052 VCO multiplexers located on both VCF Cards. When the
system is tuning, the PA lines are selected to allow the CPU to control
which VCO it is sensing; otherwise, the CD4052s are scanned by the
mod system clocks so that the VCO outputs can be multiplexed in
synchronization with the mod system scan rate.
