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#35b Dual Serial Module with Z80 SIO/2, RS232 port and Crystal Oscillator

Nearly a year after the first version of the SIO/2 module I have finally released the design. The module above was named #33 before the module clean-up, I have now made 2 versions, #34 with 2 FTDI ports, and #35 with and additional RS232 port. (The current #33 is a serial module with 68B50 ACIA). Also this module works fine, but If you are looking for a dual serial module I would recommend Steve Cousins SC104 SIO/2 module, mainly because it is better documented.


  • Z0844204PSC - Z084408PSC (cmos)
  • Crystal Oscillator
  • (rec. 7.3728Mhz = 115200 baud)
  • (rec 3.6864Mhz = 57600 baud)
  • Address selectable
  • 51 x 102 mm
  • RC40 bus connector
  • 2 FTDI-ports
  • 1 rs232 port


  • PCB - 35b
  • DIP-40 socket
  • DIP-16 socket (2x)
  • DIP-14 socket
  • Z0844204PSC or better
  • 74HCT138N
  • 74HCT02N
  • MAX232
  • Crystal Oscillator, rec. 7.3728/3.6864Mhz
  • 2.2k resistors (8x)
  • 10k resistor
  • 100nF capacitors (5x)
  • 1uF/25V electrolytic capacitor (5x)
  • 2x8 pin male connector
  • 6pin angled male adaptor (FTDI) (2x)
  • serial (D7 female) connector
  • pins and jumpers
  • 1x40 pin angled male connector

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