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The 6502 instruction set includes BRK (opcode $00), which is technically a software interrupt (similar in spirit to the SWI mnemonic of the Motorola 6800 and ARM processors). BRK is most often used to interrupt program execution and start a machine language monitor for testing and debugging during software development.
An opcode table (also called an opcode matrix) is a visual representation of all opcodes in an instruction set. It is arranged such that each axis of the table represents an upper or lower nibble, which combined form the full byte of the opcode. Additional opcode tables can exist for additional instructions created using an opcode prefix.
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.
The Western Design Center (WDC) 65C02 microprocessor is an enhanced CMOS version of the popular nMOS-based 8-bit MOS Technology 6502.It uses less power than the original 6502, fixes several problems, and adds new instructions.
The 6507 uses a 28-pin configuration, with 13 address pins (A0..A12) and 8 data pins (D0..D7). The seven remaining pins are used for power (Vss, Vcc), the CPU timing clock (φ0, φ2), to reset the CPU (the /RES pin), to request a CPU wait state during its next memory read access (the RDY pin), and for the CPU to indicate if a read or write memory (or MMIO device) access is being performed (the ...
An illegal opcode, also called an unimplemented operation, [1] unintended opcode [2] or undocumented instruction, is an instruction to a CPU that is not mentioned in any official documentation released by the CPU's designer or manufacturer, which nevertheless has an effect.
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
This is set to zero on startup or reset, meaning that its store-Z-to-memory instruction, STZ, works just like it does in the 65C02 where the same instruction means store-zero-to-memory. This allows unmodified 65C02 code to run on the 65CE02. A number of other instructions are added or modified to allow access to the Z register.