The SC521, serial card houses a Z80 SIO chip, which provides two TTL serial ports for use with FTDI style serial adapter cables.

The main features of this card are:

• Z50Bus compatible (“Standard” card size 100mm x 75mm)
• Full Z80 mode 2 interrupt support (IEI/IEO daisy-chain)
• Two TTL serial ports for use with FTDI serial adapter cables
• Baud rate set with jumper shunt (2400 to 115200 baud)
• On-board oscillator for independence from CPU clock rate
• Device address set with jumper shunts
• Optional connection of either port to Z50Bus RX/TX pins