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#63b Z80 CPU and Serial I/O

Revised version
Now with two oscillators, individual adjust speed for CPU and 68B50.
The I/O address of 68B50 can be selected, and now working with ROMWBW.
Also fixed the blinking LEDs for TX and RX.


  • Z80 CPU
  • MC68B50P ACIA
  • 51 x 102 mm
  • RC40+10 bus connector


  • PCB - 63b
  • Z80 CPU - Z84C0020xxx
  • DIP-40 socket
  • MC68B50P ACIA
  • DIP-24 socket
  • 74HCT138
  • DIP-16 socket
  • 74HCT02
  • DIP-14 socket
  • 100nF capacitors (6x) (C1-C6)
  • 10k resistor (5x) (R1-R5)
  • 2k2 resistor (3x) (R6-R8)
  • 330ohm resistors (2x) (R9-R10)
  • Crystal Oscillator (2x)
  • —> rec. 7.3728Mhz for serial and 20Mhz for CPU
  • LEDs (2x)
  • pins and jumpers
  • 1x6 angled male pin
  • 2x40 pin angled male connector (remove some pins)

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This is a slot saving module, combining the CPU, serial I/O and dual clock functions.