The BU34440 is a single-chip 4-bit microcontroller designed for CD-DA and contains parallel I / O, serial I / O, timer / counter and all other functions required for CD control in a single compact package.

FEATUREs
1) Low-voltage, high-speed operation (VDD=2.3
5.5V at 4.4MHz).
2) 4k byte ROM, 256 nibble RAM.
3) Internal 8-bit SIO (LSB first).
4) 14 programmable pull-up input / outputs.
5) 5 programmable pull-up inputs.

APPLICATIONs
    Portable CD-DA devices, portable CD stereos