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One popular 6502-based computer, the Commodore 64, used a modified 6502 CPU, the 6510. Unlike the 6503–6505 and 6507, the 6510 is a 40-pin chip that adds internal hardware: a 6-bit parallel I/O port mapped to addresses 0000 and 0001.
An instruction set architecture (ISA) is an abstract model of a computer, also referred to as computer architecture.A realization of an ISA is called an implementation.An ISA permits multiple implementations that may vary in performance, physical size, and monetary cost (among other things); because the ISA serves as the interface between software and hardware.
In computer science, an instruction set architecture (ISA) is an abstract model that generally defines how software controls the CPU in a computer or a family of computers. [1] A device or program that executes instructions described by that ISA, such as a central processing unit (CPU), is called an implementation of that ISA.
Encoding a number in the machine code requires several bits. ... An example of this approach is the MOS 6502, ... (ISA). For instance, the ...
The methods by which the MPU state is preserved and restored within an ISR will vary with the different versions of the 65xx family. For NMOS processors (e.g., 6502, 6510, 8502, etc.), there can be only one method by which the accumulator and index registers are preserved, as only the accumulator can be pushed to and pulled from the stack. [5]
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.
In the example ISA outlined above, the ADD.C instruction using direct encoding already has the data it needs to run the instruction and no further processing is needed, the decoder simply sends the value into the arithmetic logic unit (ALU).
But the real value in the 360 line was that one could build a series of machines that were completely different internally, yet run the same ISA. For a low-end machine, one might use an 8-bit ALU that requires multiple cycles to complete a single 32-bit addition, while a higher end machine might have a full 32-bit ALU that performs the same ...