INTRODUCTION
The MC68HC05F4 is a member of the M68HC05 family of HCMOS microcomputers. In addition to 4K bytes of ROM, the MC68HC05F4 contains 256 bytes of RAM and 256 bytes of EEPROM. The on-board features of this device make it particularly suited to highly integrated and cost effective telephone handsets. The timer and DTMF generator allow for both pulse and tone dialling; in addition to telephone set-up parameters and features such as last number redial, the EEPROM can typically store up to 12 telephone numbers of 20 digits, even after power has been removed from the circuit; the keyboard interrupt facility permits a direct interface to a telephone keypad. In addition to the high level of integration achieved, careful attention has also been paid to the low-power and low-voltage performance of the MC68HC05F4, which is of major importance in many telecommunications applications.
The MC68HC705F4 is an EPROM version of the MC68HC05F4, with the User ROM replaced by 8kbytes of EPROM. All references to the MC68HC05F4 apply equally to the MC68HC705F4, unless otherwise noted.

FEATUREs
• Fully static design featuring the industry-standard M68HC05 CPU core
• 3840 bytes of user ROM, plus 16 bytes for vectors
• 256 bytes of RAM
• 256 bytes of user EEPROM
• DTMF/melody generator
• 16-bit programmable timer with two input captures and two output compares
• 15 stage multipurpose core timer with timer overflow, real time interrupt and COP watchdog
• COP watchdog timer (mask option)
• Power saving STOP and WAIT modes
• I/O lines (8 with high-voltage, open-drain outputs)
   – 44 QFP configuration – total of 32 dedicated bidirectional I/O pins
   – 28 SOIC/PDIP configuration – total of 16 dedicated bidirectional I/O pins
• Keyboard interrupt facility on eight of the I/O lines
• Hardware interrupt with edge or edge-and-level sensitive interrupt trigger
• On-chip oscillator
• On-chip low voltage detection circuit
• Two selectable bus frequencies
• Power-on and power-off resets; low voltage detection circuitry (EEPROM)
• Available in 44-pin QFP package, 28-pin SOIC package and 28-pin PDIP package (ports C and D not available in 28-pin packages)