decimal adjust circuitry of
- In this post I reverse-engineer and describe the simple decimal adjust circuit in the 8085 microprocessor. Binary-coded decimal arithmetic was an important performance feature on early microprocessors. The idea behind BCD is to store two 4-bit decimal numbers in a byte. For instance, the number 42 is represented in BCD as 0100 0010 (0x42) instead of binary 00101010 (0x2a). This continues my reverse engineering series on the 8085’s ALU, flag logic, undocumented flags, register file, and instruction set.
