13 Facts About WDC 65C02

Western Design Center 65C02 microprocessor is an enhanced CMOS version of the popular nMOS-based 8-bit MOS Technology 6502.

The WDC 65C02 fixed several problems in the original 6502 and added some new instructions, but its main feature was greatly lowered power usage, on the order of 10 to 20 times less than the original 6502 running at the same speed.

WDC 65C02 licensed the design to Synertek, NCR, GTE, and Rockwell Semiconductor.

WDC 65C02 is a low cost, general-purpose 8-bit microprocessor with a 16-bit program counter and address bus.

Basic architecture of the WDC 65C02 is identical to the original 6502, and can be considered a low-power implementation of that design.

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WDC 65C02 adds new opcodes that use some of these previously undocumented instruction slots.

The WDC 65C02 automatically clears this flag after pushing the status register onto the stack in response any interrupt or in response to a hardware reset, thus placing the processor back into binary arithmetic mode.

The WDC 65C02 fixed this problem by performing a dummy read of the instruction opcode when indexing crosses a page boundary.

The WDC 65C02 added a non-indexed indirect addressing mode LDA to all instructions that used indexed indirect and indirect indexed modes, freeing up the index registers.

WDC 65C02 added the new "indexed absolute indirect" mode which eased the use of branch tables.

WDC 65C02 added new addressing modes to the BIT instruction that was present in the 6502, as well two new instructions for convenient manipulation of bit fields, a common activity in device drivers.

BIT in the WDC 65C02 adds immediate mode, zero page indexed by X and absolute indexed by X addressing.

In contrast, in the WDC 65C02, interrupt code could be written by having a WAI followed immediately by a JSR or JMP to the handler.