What's that? Look like a Wavecomputer 360A mainboard.
Hey, it IS a 360A mainboard! The system bus connector for the 340/380 system is just wire wrapped to the bus lines. The mainboard is populated with 4 generator boards, a stripped-down TONRAM (wave memory) and an IO board with no brain, lacking RAM and PROM.



This is the brain-less IO board of the 340.
There's some minor modifications in the control voltage generation for the master oscillator.
Stay tuned while reverse engineering goes on!



Two RAM boards of a PPG 340B brain unit. Each board features 16kBytes of static RAM, using 32 pieces 2114 RAM chips. One is mapped in the range 0000-3FFF, the other is splitted to 8000-9FFF and C000-DFFF. The latter is connected to the Write Protect switch on the front panel.



While the upper board is a PROM board from the Wavecomputer 360 with four pieces 2708 EPROMs mapped to F000-FFFF, the lower is a board called WA which originally maps 8 2716 EPROMs and 10 2114 SRAMs into the address space, but is modified to allow two 2716 to be located at F000-FFFF as well.
No idea for which this board was originally made, the address ranges neither fit those of the Wavecomputer, nor any of the Wave family.



The wavetable RAM from a 340A. It's the same PCB as in the Wavecomputer 360(A,B), but with twice the memory (8kByte) on it.
Reason: The Wavecomputer has some logic to invert the lower address lines (those making up one "wave") and the data lines of the RAM (2s complement!), thereby allowing for doubling the stored waveforms by making the second half-wave the inverted image of the first.
The 340A does not have this ingenious memory-saving trick, thereby removing the restriction on purely periodic waveforms.
Some address lines are wire-wrapped on this board to make all this possible, but the function is the same as in the Wavecomputer: the CPU loads the waves into this boards RAM which are played back through the generator boards.



Here's the answer why this one has twice the phone jacks than other 340s have :)