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mdfs.net – 6502 instruction set; Clever, Eric. "6502 – the first RISC µP". Archived from the original on 24 May 2012. Harrod, Dennette A. (October 1980). "6502 Gets Microprogrammable Instructions". Byte. Vol. 5, no. 10. McGraw Hill. pp. 282– 285. ISSN 0360-5280. Archived from the original on 2006-05-25; Simulators, emulators
If the instruction required only one byte, the processor still read the following byte as it decoded the first. In this case the next byte was the following instruction, but it had no way to feed that back into the first stage of the pipeline to decode it. The fetched instruction was instead discarded and re-read to feed it into the decoder.
For instance, the MOS 6502 has eight instructions for performing addition, differing only in where they collect their operands. [2] Actually making these instructions work required circuitry in the CPU, which was a significant limitation in early designs and required designers to select just those instructions that were really needed.
The most significant byte (MSB) of the aborted instruction's address is pushed onto the stack. The least significant byte (LSB) of the aborted instruction's address is pushed onto the stack. The status register is pushed onto the stack. The interrupt disable flag is set in the status register. PB is loaded with $00.
It has 92 instructions, an 8-bit data bus, a 16-bit accumulator, and a 24-bit address bus. The CPU runs between 1.79 MHz and 3.58 MHz, and uses an extended MOS Technology 6502 instruction set . Major features
The Mitsubishi 740 family has a processor core that executes a superset of the 6502 instruction set including many of the extensions added in the 65C02. There is a core set of new instructions common across all 740 family members, plus other instructions that exist in specific parts. [1]
After a short stint consulting for a local company called ICE, he set up the Western Design Center (WDC) in 1978. As a licensee of the 6502 line, their first products were bug-fixed, power-efficient CMOS versions of the 6502 (the 65C02, both as a separate chip and embedded inside a microcontroller called the 65C150).
The HuC6280 contains a 65C02 core which has several additional instructions and a few internal peripheral functions such as an interrupt controller, a memory management unit, a timer, an 8-bit parallel I/O port, and a programmable sound generator (PSG). The processor operates at two speeds, 1.79 MHz and 7.16 MHz.