Intel 8085

From Misc Data Digs

Undocumented flags[edit | edit source]

The flags register has two undocumented bits.

Bit 1 (Overflow, V)[edit | edit source]

Signals whenever the result of an operation is too big to fit within a register.

Bit 5 (Signed Compared, k)[edit | edit source]

This is the V bit XOR'ed with the sign of the result and is used to compare signed numbers.

(Source: Ken Shirriff)

Undocumented opcodes[edit | edit source]

The following opcodes are present, but not called up:

Opcode Name Effect
0x08 dsub
0x10 arhl
0x18 rdel
0x20 rim Reads Interrupt Mask
0x28 ldhi r8
0x30 sim Set Interrupt Mask
0x38 ldsi r8
0xCB rstv
0xD9 shlx
0xDD jnk a16
0xED lhlx
0xFD jk a16

(Source: Ken Shirriff)