PBus Description

- signal description
  input and output are with respect to the interface board

  - pb_clk (output) - clock

  - pb_d [15:0] (I/O) - data bus

  - pb_eofout (output) - handshake signal:
      write mode:
        1 = invalid data is on bus
        0 = valid data is on bus
      read mode:
        1 = not ready to accept data
        0 = ready to accept data

  - pb_eofin (input) - handshake signal:
      write mode:
        1 = not ready to accept data
        0 = ready to accept data
      read mode:
        1 = valid data is on bus
        0 = invalid data is on bus

  - pb_iosel (output) - control/data select signal:
        1 = data transfer mode
        0 = control mode (parity and opcode)

  - pb_sync (output) - encoded sync signal:
  - 
- electrical specs
  static
  dynamic