The ML22Q54/Q58 is a speech synthesis device with a 4-Mbit flash memory built in. The voice data can be easily written to the flash memory using a special tool. The on-chip flash memory product is suitable for the diversified low volume production or short delivery time applications that the on-chip mask ROM product cannot support. The ML22Q54/Q58 is most suitable for evaluation because the circuit configuration is the same as the on-chip mask ROM product. As it is easy to write to build in-flash memory, it is able to combine fixed message and variable message.