Saturday, August 4, 2007

Undocumented 8085 Instructions

8085 undocumented instructions
These are the undocumented 8085 instructions, undocumented due to incompatibility with 8086, Use them at your discretion. (information here is not sure yet, still worth a post)

DSUB
Hex Code: 08H
Description: BC pair is subtracted from HL Pair affecting all flags.

JNK [16bit location] - Jump to Location if 'K' flag is reset
Hex code : DDH

JK [16bit location] - Jump to Location if 'K' flag is set
Hex Code: FDH

RRHL - Rotate Right HL Pair
Description: Rotates the HL pair 16 bit towards right.
Hex code : 10H
Operands : none
Flags unaffected


RLDE - Rotate Left DE Pair
Description: Rotates DE Pair to left.
Hex code: 18H
Operands : none
Carry affected : depends on Bit 15

ADI HL - Add Immidiate to HL pair
Description: Adds an 8 byte number to the HL pair.
Hex Code : 28H
Operands : 8 bit number
Flags: All affected

ADI SP - Add Immidiate to Stack Pointer
Description: Adds an 8 byte number to the SP
Hex Code : 38H
Operands : 8 bit number
Flags: All affected

RSTV
Description: Does a RST 8 instruction when the 'V' (must be overflow)flag is SET.
Hex Code: CBH

LHLX
Description: Loads HL Pair with the contents of address stored in the DE pair
Hex Code: EDH

SHLX
Description: Stores the HL Pair contents to the address specified in the DE pair.
Hex Code: D9H


Help me!
Whats this K flag ? Any Intel engineers out there ?