The 38B4 group is the 8-bit microcomputer based on the 740 family core technology.

The 38B4 group has six 8-bit timers, a 16-bit timer, a fluorescent display automatic display circuit, 12-channel 10-bit A-D converter, a serial I/O with automatic transfer function, which are available for controlling musical instruments and household appliances.

FEATURES
* Basic machine-language instructions ...... 71
* Minimum instruction execution time ........... 0.48 µs(at 4.2 MHz oscillation frequency)
* Memory size
   ROM ............ 48K to 60K bytes
   RAM .........1024 to 2048 bytes
* Programmable input/output ports ............ 51
* High-breakdown-voltage output ports ..... 36
* Software pull-up resistors (Ports P5, P61to P65, P7, P84to P87,P9)
* Interrupts ...... 21 sources, 16 vectors
* Timers ............... 8-bit ✕ 6, 16-bit ✕ 1
* Serial I/O1 (Clock-synchronized) ............. 8-bit ✕ 1z
  (max. 256-byte automatic transfer function)
* Serial I/O2 (UART or Clock-synchronized) ......... 8-bit ✕ 1
* PWM .......... 14-bit ✕ 1,  8-bit ✕ 1 (also functions as timer 6)
* A-D converter ............. 10-bit ✕12 channels
* Fluorescent display function ... Total 40 control pins
* Interrupt interval determination function .... 1
* Watchdog timer ..... 20-bit ✕1