General Description:
The AU1564, AU1564A, AU2064, AU2064A is a single chip voice synthesizer with 4-bit microprocessor. That can synthesize voice up to 15, 20 seconds by ALPHA qualified coding algorithm (LOGPCM).
The 4-bit microprocessor has various feature including 4-bit ALU, 1K×15 bits ROM, 64×4 bits RAM, I/O port, timer, clock generator, LCD driver, etc. The instruction set with 78 instructions. With the half function can minimize power dissipation.

Features:
1. Single power supply can operate from 2.4V through 6V
2. The total voice duration is about 15, 20 seconds could be partitioned up to 64 sections
    (AU1564, AU1564A -->15 seconds, AU2064, AU2064A -->20 seconds)
3. The voice can be triggered by microprocessor instructions
4. Current output could drive 8 ohm speaker with a transistor, VOUT could drive buzzer or
64 ohm directly.
5. LCD driver provided, up to 3× 24=72 segments. Build-in HALVER circuitry.
6. Build-in clock generator
7. Internal ROM: 1024×15 bits
    Internal RAM: 64×4 bits
8. Two 4-bit input ports (AU1564, AU1564A has no S4 pad)
9. Two 4-bit I/O ports
10. One 4-bit output port
11. One control output pins
12. 78 instructions
13. 4-level subroutine nesting (also used for interrupt)
14. Two external factors (INT, S & M port) for interrupt
15. Two internal factors (Timer , Divider) for interrupt
16. Three current output level 1.5mA, 3mA, 4.5mA is mask option (full scale).
    (AU1564, AU1564A has no COUT output function)