General Description
Introduction
The MC68HC705C4A is a member of the low-cost, high-performance M68HC05 Family of 8-bit microcontroller units (MCUs). The M68HC05 Family is based on the customer-specified integrated circuit (CSIC) design strategy. All MCUs in the family use the M68HC05 central processor unit (CPU) and are available with a variety of subsystems, memory sizes and types, and package types.
The MC68HC705C4A is similar to the MC68HC705C8A. The major differences are that the MC68HC705C4A has less RAM and ROM, no selectable memory configurations, no clock monitor reset function, and only one computer operating properly (COP) watchdog timer. The MC68HSC705C4A, introduced in Appendix A. MC68HSC705C4A, is an enhanced, high-speed version of the MC68HC705C4A.

FEATUREs
Features of the MC68HC705C4A include:
• M68HC05 central processor unit (CPU)
• On-chip oscillator with crystal/ceramic resonator
• Memory-mapped input/output (I/O)
• Computer operating properly (COP) watchdog timer
• Selectable port B external interrupt capability
• High current drive on pin C7 (PC7)
• 24 bidirectional I/O lines and 7 input-only lines
• Serial communications interface (SCI) system
• Serial peripheral interface (SPI) system
• Bootstrap capability
• Power-saving stop, wait, and data-retention modes
• Single 3.0-volt to 5.5-volt supply (2-volt data-retention mode)
• Fully static operation
• Software-programmable external interrupt sensitivity