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)