Renesas 740
The 740 Family is a collection of 8-bit microcontrollers made by Renesas Electronics based on an upgraded CMOS version of the MOS Technology 6502 processor core. The family was originally designed by the Mitsubishi Electric semiconductor group.
Variants
Subfamilies include the 3800, 38000, 7400 and 7500 groups. Individual parts are generally classified based on package type, pin count, ROM size, ROM type, RAM size and included peripherals (such as timers, serial UART, USB controller).
Comparison with the MOS 6502
The 740 Family consists of microcontrollers as opposed to stand-alone microprocessors. To achieve the similar configurations, the original 6502 had to be paired with a secondary IC such as the MOS RIOT or MOS RRIOT or discrete components.
Several additional instructions are available in the 740 Family. The branch always (BRA) and accumulator increment (INA) and decrement (DEA) instructions from the WDC 65C02 are included. Several bit manipulation (CLB, SEB) and bit branching (BBC, BBS) instructions similar to those from the Rockwell 65SC02 are also included. Lastly, hardware multiplication and division instructions are available.
The Stack Page can be relocated from $01xx to $00xx, allowing the use of stack instructions on systems with only 128 or 256 bytes of RAM.
A special read-calculate-write mode can be enabled that allows the results of arithmetic operations to be stored in any Zero Page location as opposed to the accumulator. The Zero Page address is controlled by the Index X register.
The family supports bank switching, allowing programs to choose between internal ROM and external RAM for select addresses, similar to the MOS Technology 6510.