Introduction
The MC68HC05J1A is a member of the low-cost, high-performance M68HC05 Family of 8-bit microcontroller units (MCU). The M68HC05 Family is based on the customer-specified integrated circuit (CSIC) design strategy. All MCUs in the family use the popular M68HC05 central processor unit (CPU) and are available with a variety of subsystems, memory sizes and types, and package types.

On-chip memory of the MC68HC05J1A includes:
• 1240 bytes of user read-only memory (ROM)
• 64 bytes of user random-access memory (RAM)

FEATUREs
Features of the MCU include:
• Popular M68HC05 CPU
• Memory-mapped input/output (I/O) registers
• 1240 bytes of user ROM including eight user vector locations
• 64 bytes of user RAM
• 14 bidirectional I/O pins with these features:
   – Software programmable pulldown devices
   – Four I/O pins with 8-mA current sinking capability
   – Four I/O pins with maskable external interrupt capability
• Hardware mask and flag for external interrupts
• Fully static operation with no minimum clock speed
• On-chip oscillator with connections for a crystal or ceramic resonator or for a resistor-capacitor (RC) network
• 15-bit multifunction timer
• Computer operating properly (COP) watchdog
• Power-saving stop (or halt), wait, and data-retention modes
• Illegal address reset
• Internal steering diode between RESET and VDD pins
• 8 × 8 unsigned multiply instruction
• 20-pin plastic dual in-line package (PDIP)
• 20-pin small outline integrated circuit package (SOIC)