Dey

DEY is an opcode for the 6502 processor. It decreases the value in the Y register by 1. If the register contains zero before this instruction is executed, its value will wrap around so that it contains 255 (equivalent to -1 in 8-bit 2's complement arithmetic).

The N and Z flags may be affected by this instruction's execution.

The machine code representation of this opcode is 0x88.

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1. My initials (Damian E. Yerrick).

2. A 6502 instruction that subtracts 1 from register Y, wrapping the value to 255 if it's already zero.

• Function: Y--
• Updates flags: S . . . . . Z .
• Opcode numbers:

  impl  $88
  

Similar: DEC | DEX | INC | INX | INY
See also: 6502 instructions | 6502 addressing modes

Dey (?), n. [See Dairy.]

A servant who has charge of the dairy; a dairymaid.

[Obs.]

Chaucer.

 

© Webster 1913.

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Dey (?), n.; pl. Deys (#). [Turk. dai, orig., a maternal uncle, then a friendly title formerly given to middle-aged or old people, especially among the Janizaries; and hence, in Algiers, consecrated at length to the commanding officer of that corps, who frequently became afterward pasha or regent of that province; hence the European misnomer of dey, as applied to the latter: cf. F. dey.]

The governor of Algiers; -- so called before the French conquest in 1830.

 

© Webster 1913.