Search results
Results from the WOW.Com Content Network
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.
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.
Due to the way the 6502's instruction decoder works, simply setting certain bits in the opcode cause parts of the instruction processing to take place. Some of these opcodes immediately crash the processor, while other perform useful functions and were even given unofficial assembler mnemonics by some programmers. [9]
Internals of BRK/IRQ/NMI/RESET on a MOS 6502; Brad Taylor. "6502 'B' flag & BRK Opcode". 6502 Family Microprocessor Resources and Forum; 65xx Interrupt Primer – An extensive discussion of 65xx family interrupt processing. Investigating 65C816 Interrupts – An extensive discussion of interrupt processing that is specific to 65C816 native mode ...
The Motorola 6800 microprocessor was the first for which an undocumented assembly mnemonic HCF became widely known. The operation codes (opcodes—the portions of the machine language instructions that specify an operation to be performed) hexadecimal 9D and DD were reported and given the unofficial mnemonic HCF in a December 1977 article by Gerry Wheeler in BYTE magazine on undocumented ...
Opcode for OR 0,0,0. [7] LDI 26,0: 4 0x34000034 Palindromic NOP - that is, an instruction that executes as NOP regardless of whether byte order is interpreted as little-endian or big-endian. Some PA-RISC system instructions are required to be followed by seven palindromic NOPs. [7] POWER, PowerPC, Power ISA: NOP: 4 0x60000000 Opcode for ori r0 ...
3 6501<>6502 slot converters? 6 comments. 4 Clock multiplication. 1 comment. 5 Terminator 6502 code. 2 comments. 6 MOS Technology? 7 Memory Access. 18 comments. 8 MHz.
The CSG 65CE02 is an 8/16-bit microprocessor developed by Commodore Semiconductor Group in 1988. [1] It is a member of the MOS Technology 6502 family, developed from the CMOS WDC 65C02 released by the Western Design Center in 1983.