Synthetic programming (HP-41)
| Industry | Calculator programming |
|---|---|
| Products | HP-41C, Elektronika B3-34, HP-15C |
Synthetic programming (SP) represents a sophisticated method used for programming the HP-41C and Elektronika B3-34 programmable calculators. This approach involves generating instructions or instruction combinations that cannot be input through the calculators' standard interfaces.
Within the HP-41C, some instructions occupy multiple bytes in memory. Certain sequences of these bytes correspond to valid executable commands but are inaccessible via normal input methods. Synthetic programming takes advantage of a firmware flaw to insert these byte sequences by encoding them as different instructions and then partially bypassing execution partway through the initial instruction. This technique deceives the calculator into recognizing new commands and is commonly referred to as byte jumper or byte grabber.
It remains uncertain whether HP's engineers were fully aware of these so-called "black holes." Despite HP not officially endorsing synthetic programming, they occasionally expressed interest and even permitted dedicated users to explore and enhance the system driven by curiosity.
HP-15C
Synthetic programming can also be applied to the original HP-15C, enabling programmers to extend its capabilities beyond those officially provided.
See also
- Casio FX-602P series
- Illegal opcode
- Logic synthesis
- NOMAS (support)
- Overlapping instructions
- Self-modifying code
- Side effect (computer science)
- Variable-length instruction set
- Yeggogology (Cyrillic: "Еггогология")