The SC511, serial and timer card houses a Z80 SIO chip, which provides two TTL serial ports for use with FTDI style serial adapter cables, and a Z80 CTC, which has four counter/timer channels.

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)
- Interrupt look-ahead circuit
- Two TTL serial ports for use with FTDI serial adapter cables
- Software control of baud rate for both ports
- On-board oscillator for independence from CPU clock rate
- Clock tick timer
- Two I/O address options
- Optional connection of either port to Z50Bus RX/TX pins