The MC145442B has been discontinued. Suggested replacement: none.
The MC145442B is a silicon-gate CMOS single-chip, low-speed modem containing a complete frequency shift keying (FSK) modulator, demodulator, and filter. This device is compatible with CCITT V.21 specifications. The MC145442B provides full-duplex or half-duplex 300-baud data communication over a pair of telephone lines. It also includes a carrier detect circuit for the demodulator section and a duplexer
circuit for direct operation on a telephone line through a simple transformer.