Intel 80386

From Misc Data Digs

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Revision Differences[edit | edit source]

Steppings A0 and B0 contain two instructions not in any future instruction sets, XBTS (eXtract BiT String; opcode FH A6) and IBTS (Insert BiT String; opcode FH A7).

Undocumented Instructions[edit | edit source]

LOADALLD[edit | edit source]

Opcode 0F 07 loads all registers from memory address ES:EDI. It is only available with the 80386.

ICEBP[edit | edit source]

Opcode F1 allows for one to use the in-circuit emulator, allowing for a single-byte, single-step execution method. This wouldn't be documented until the Pentium Pro, where it was called INT1.

UMOV[edit | edit source]

Opcodes 0F 10, 0F 11, 0F 12, and 0F 13 is intended for ICE host software to cycle through memory during HALT mode.