I will be using the Free Software program Qucs to plan out the electronics of the RAVEN.
The digital electronics of this computer will be based on the R-Series logic of the DEC PDP-8/S.
I started planning out the registers of the RAVEN, following this 'cookbook' suggestion inside the 1967 DEC Logic Handbook:
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The DIRECT SET lines will not be tied together, and they will not be unbuffered. The DIRECT SET lines will have a three state input implemented with an extra R-Series Diode-Capacitor-Diode Gate attached to each separated DIRECT SET line:
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So the extra 'CLEAR MDR' control signal will be implemented by attaching all DIRECT CLEAR lines together. This will be useful for the CLEAR STACK CELL control signal/sequence.
Flip-Flops Required for Registers
This is a 5-input single Flip-Flop as specified by DEC Flip-Chip code R201:
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And this is the corresponding circuit schematic in Qucs:
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And this is the sub-circuit schematic that is generated by attaching ports to the appropriate inputs and outputs:
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Now the registers can be designed (and hopefully simulated) in Qucs and an accurate Bill of Materials can be generated.
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