As we know that the 8085 microprocessor is an 8-bit microprocessor. So, a total of 256 instruction codes can be generated using 8-bit combinations. But out of 256 instruction codes, only 246 instruction codes are defined by INTEL Corporation for 8085 microprocessor. Each defined instruction code performs a unique task. These instruction codes are called operational code or opcode. There are exact 74 basic functions. The size of the 8085 microprocessor instruction code (or opcode) can either be one-byte or two-bytes or three-bytes.
The following table shows the possible combinations of instruction codes from the 8-bit combinations. Each hexadecimal equivalent is mentioned across each instruction code.
| Instruction Code | Binary | Hexadecimal |
| Code instruction #1 | 0000 0000 | 00 H |
| Code instruction #2 | 0000 0001 | 01 H |
. . .
. . .
. . .
| Code instruction #255 | 1111 1110 | FE H |
| Code instruction #256 | 1111 1111 | FF H |
Let us take an example of instruction codes given by Intel corporation.
MOV A,B
The above instruction has a task to move the data present in register B to the accumulator A. The binary code corresponding to this instruction is 0111 1000 and its opcode is 78 H.
ADD C
This instruction has a task to add the data present in register C with the accumulator (A) and store the result in the accumulator. The binary code corresponding to this instruction is 10000001 and its opcode is 81 H.
Opcodes Table of 8085 Microprocessor
Here is the complete list of the instruction set of 8085 microprocessor.
| S.No. | Mnemonics, Operand | Opcode | Instruction Word Size |
| 1. | ACI Data | CE | 2 Bytes |
| 2. | ADC A | 8F | 1 Byte |
| 3. | ADC B | 88 | 1 Byte |
| 4. | ADC C | 89 | 1 Byte |
| 5. | ADC D | 8A | 1 Byte |
| 6. | ADC E | 8B | 1 Byte |
| 7. | ADC H | 8C | 1 Byte |
| 8. | ADC L | 8D | 1 Byte |
| 9. | ADC M | 8E | 1 Byte |
| 10. | ADD A | 87 | 1 Byte |
| 11. | ADD B | 80 | 1 Byte |
| 12. | ADD C | 81 | 1 Byte |
| 13. | ADD D | 82 | 1 Byte |
| 14. | ADD E | 83 | 1 Byte |
| 15. | ADD H | 84 | 1 Byte |
| 16. | ADD L | 85 | 1 Byte |
| 17. | ADD M | 86 | 1 Byte |
| 18. | ADI Data | C6 | 2 Bytes |
| 19. | ANA A | A7 | 1 Byte |
| 20. | ANA B | A0 | 1 Byte |
| 21. | ANA C | A1 | 1 Byte |
| 22. | ANA D | A2 | 1 Byte |
| 23. | ANA E | A3 | 1 Byte |
| 24. | ANA H | A4 | 1 Byte |
| 25. | ANA L | A5 | 1 Byte |
| 26. | ANA M | A6 | 1 Byte |
| 27. | ANI Data | E6 | 2 Bytes |
| 28. | CALL Label | CD | 3 Bytes |
| 29. | CC Label | DC | 3 Bytes |
| 30. | CM Label | FC | 3 Bytes |
| 31. | CMA | 2F | 1 Byte |
| 32. | CMC | 3F | 1 Byte |
| 33. | CMP A | BF | 1 Byte |
| 34. | CMP B | B8 | 1 Byte |
| 35. | CMP C | B9 | 1 Byte |
| 36. | CMP D | BA | 1 Byte |
| 37. | CMP E | BB | 1 Byte |
| 38. | CMP H | BC | 1 Byte |
| 39. | CMP L | BD | 1 Byte |
| 40. | CMP M | BD | 1 Byte |
| 41. | CNC Label | D4 | 3 Bytes |
| 42. | CNZ Label | C4 | 3 Bytes |
| 43. | CP Label | F4 | 3 Bytes |
| 44. | CPE Label | EC | 3 Bytes |
| 45. | CPI Data | FE | 2 Bytes |
| 46. | CPO Label | E4 | 3 Bytes |
| 47. | CZ Label | CC | 3 Bytes |
| 48. | DAA | 27 | 1 Byte |
| 49. | DAD B | 09 | 1 Byte |
| 50. | DAD D | 19 | 1 Byte |
| 51. | DAD H | 29 | 1 Byte |
| 52. | DAD SP | 39 | 1 Byte |
| 53. | DCR A | 3D | 1 Byte |
| 54. | DCR B | 05 | 1 Byte |
| 55. | DCR C | 0D | 1 Byte |
| 56. | DCR D | 15 | 1 Byte |
| 57. | DCR E | 1D | 1 Byte |
| 58. | DCR H | 25 | 1 Byte |
| 59. | DCR L | 2D | 1 Byte |
| 60. | DCR M | 35 | 1 Byte |
| 61. | DCX B | 0B | 1 Byte |
| 62. | DCX D | 1B | 1 Byte |
| 63. | DCX H | 2B | 1 Byte |
| 64. | DCX SP | 3B | 1 Byte |
| 65. | DI | F3 | 1 Byte |
| 66. | EI | FB | 1 Byte |
| 67. | HLT | 76 | 1 Byte |
| 68. | IN Port-address | DB | 2 Bytes |
| 69. | INR A | 3C | 1 Byte |
| 70. | INR B | 04 | 1 Byte |
| 71. | INR C | 0C | 1 Byte |
| 72. | INR D | 14 | 1 Byte |
| 73. | INR E | 1C | 1 Byte |
| 74. | INR H | 24 | 1 Byte |
| 75. | INR L | 2C | 1 Byte |
| 76. | INR M | 34 | 1 Byte |
| 77. | INX B | 03 | 1 Byte |
| 78. | INX D | 13 | 1 Byte |
| 79. | INX H | 23 | 1 Byte |
| 80. | INX SP | 33 | 1 Byte |
| 81. | JC Label | DA | 3 Bytes |
| 82. | JM Label | FA | 3 Bytes |
| 83. | JMP Label | C3 | 3 Bytes |
| 84. | JNC Label | D2 | 3 Bytes |
| 85. | JNZ Label | C2 | 3 Bytes |
| 86. | JP Label | F2 | 3 Bytes |
| 87. | JPE Label | EA | 3 Bytes |
| 88. | JPO Label | E2 | 3 Bytes |
| 89. | JZ Label | CA | 3 Bytes |
| 90. | LDA Address | 3A | 3 Bytes |
| 91. | LDAX B | 0A | 1 Byte |
| 92. | LDAX D | 1A | 1 Byte |
| 93. | LHLD Address | 2A | 3 Bytes |
| 94. | LXI B | 01 | 3 Bytes |
| 95. | LXI D | 11 | 3 Bytes |
| 96. | LXI H | 21 | 3 Bytes |
| 97. | LXI SP | 31 | 3 Bytes |
| 98. | MOV A, A | 7F | 1 Byte |
| 99. | MOV A, B | 78 | 1 Byte |
| 100. | MOV A, C | 79 | 1 Byte |
| 101. | MOV A, D | 7A | 1 Byte |
| 102. | MOV A, E | 7B | 1 Byte |
| 103. | MOV A, H | 7C | 1 Byte |
| 104. | MOV A, L | 7D | 1 Byte |
| 105. | MOV A, M | 7E | 1 Byte |
| 106. | MOV B, A | 47 | 1 Byte |
| 107. | MOV B, B | 40 | 1 Byte |
| 108. | MOV B, C | 41 | 1 Byte |
| 109. | MOV B, D | 42 | 1 Byte |
| 110. | MOV B, E | 43 | 1 Byte |
| 111. | MOV B, H | 44 | 1 Byte |
| 112. | MOV B, L | 45 | 1 Byte |
| 113. | MOV B, M | 46 | 1 Byte |
| 114. | MOV C, A | 4F | 1 Byte |
| 115. | MOV C, B | 48 | 1 Byte |
| 116. | MOV C, C | 49 | 1 Byte |
| 117. | MOV C, D | 4A | 1 Byte |
| 118. | MOV C, E | 4B | 1 Byte |
| 119. | MOV C, H | 4C | 1 Byte |
| 120. | MOV C, L | 4D | 1 Byte |
| 121. | MOV C, M | 4E | 1 Byte |
| 122. | MOV D, A | 57 | 1 Byte |
| 123. | MOV D, B | 50 | 1 Byte |
| 124. | MOV D, C | 51 | 1 Byte |
| 125. | MOV D, D | 52 | 1 Byte |
| 126. | MOV D, E | 53 | 1 Byte |
| 127. | MOV D, H | 54 | 1 Byte |
| 128. | MOV D, L | 55 | 1 Byte |
| 129. | MOV D, M | 56 | 1 Byte |
| 130. | MOV E, A | 5F | 1 Byte |
| 131. | MOV E, B | 58 | 1 Byte |
| 132. | MOV E, C | 59 | 1 Byte |
| 133. | MOV E, D | 5A | 1 Byte |
| 134. | MOV E, E | 5B | 1 Byte |
| 135. | MOV E, H | 5C | 1 Byte |
| 136. | MOV E, L | 5D | 1 Byte |
| 137. | MOV E, M | 5E | 1 Byte |
| 138. | MOV H, A | 67 | 1 Byte |
| 139. | MOV H, B | 60 | 1 Byte |
| 140. | MOV H, C | 61 | 1 Byte |
| 141. | MOV H, D | 62 | 1 Byte |
| 142. | MOV H, E | 63 | 1 Byte |
| 143. | MOV H, H | 64 | 1 Byte |
| 144. | MOV H, L | 65 | 1 Byte |
| 145. | MOV H, M | 66 | 1 Byte |
| 146. | MOV L, A | 6F | 1 Byte |
| 147. | MOV L, B | 68 | 1 Byte |
| 148. | MOV L, C | 69 | 1 Byte |
| 149. | MOV L, D | 6A | 1 Byte |
| 150. | MOV L, E | 6B | 1 Byte |
| 151. | MOV L, H | 6C | 1 Byte |
| 152. | MOV L, L | 6D | 1 Byte |
| 153. | MOV L, M | 6E | 1 Byte |
| 154. | MOV M, A | 77 | 1 Byte |
| 155. | MOV M, B | 70 | 1 Byte |
| 156. | MOV M, C | 71 | 1 Byte |
| 157. | MOV M, D | 72 | 1 Byte |
| 158. | MOV M, E | 73 | 1 Byte |
| 159. | MOV M, H | 74 | 1 Byte |
| 160. | MOV M, L | 75 | 1 Byte |
| 161. | MVI A, Data | 3E | 2 Bytes |
| 162. | MVI B, Data | 06 | 2 Bytes |
| 163. | MVI C, Data | 0E | 2 Bytes |
| 164. | MVI D, Data | 16 | 2 Bytes |
| 165. | MVI E, Data | 1E | 2 Bytes |
| 166. | MVI H, Data | 26 | 2 Bytes |
| 167. | MVI L, Data | 2E | 2 Bytes |
| 168. | MVI M, Data | 36 | 2 Bytes |
| 169. | NOP | 00 | 1 Byte |
| 170. | ORA A | B7 | 1 Byte |
| 171. | ORA B | B0 | 1 Byte |
| 172. | ORA C | B1 | 1 Byte |
| 173. | ORA D | B2 | 1 Byte |
| 174. | ORA E | B3 | 1 Byte |
| 175. | ORA H | B4 | 1 Byte |
| 176. | ORA L | B5 | 1 Byte |
| 177. | ORA M | B6 | 1 Byte |
| 178. | ORI Data | F6 | 2 Bytes |
| 179. | OUT Port-Address | D3 | 2 Bytes |
| 180. | PCHL | E9 | 1 Byte |
| 181. | POP B | C1 | 1 Byte |
| 182. | POP D | D1 | 1 Byte |
| 183. | POP H | E1 | 1 Byte |
| 184. | POP PSW | F1 | 1 Byte |
| 185. | PUSH B | C5 | 1 Byte |
| 186. | PUSH D | D5 | 1 Byte |
| 187. | PUSH H | E5 | 1 Byte |
| 188. | PUSH PSW | F5 | 1 Byte |
| 189. | RAL | 17 | 1 Byte |
| 190. | RAR | 1F | 1 Byte |
| 191. | RC | D8 | 1 Byte |
| 192. | RET | C9 | 1 Byte |
| 193. | RIM | 20 | 1 Byte |
| 194. | RLC | 07 | 1 Byte |
| 195. | RM | F8 | 1 Byte |
| 196. | RNC | D0 | 1 Byte |
| 197. | RNZ | C0 | 1 Byte |
| 198. | RP | F0 | 1 Byte |
| 199. | RPE | E8 | 1 Byte |
| 200. | RPO | E0 | 1 Byte |
| 201. | RRC | 0F | 1 Byte |
| 202. | RST 0 | C7 | 1 Byte |
| 203. | RST 1 | CF | 1 Byte |
| 204. | RST 2 | D7 | 1 Byte |
| 205. | RST 3 | DF | 1 Byte |
| 206. | RST 4 | E7 | 1 Byte |
| 207. | RST 5 | EF | 1 Byte |
| 208. | RST 6 | F7 | 1 Byte |
| 209. | RST 7 | FF | 1 Byte |
| 210. | RZ | C8 | 1 Byte |
| 211. | SBB A | 9F | 1 Byte |
| 212. | SBB B | 98 | 1 Byte |
| 213. | SBB C | 99 | 1 Byte |
| 214. | SBB D | 9A | 1 Byte |
| 215. | SBB E | 9B | 1 Byte |
| 216. | SBB H | 9C | 1 Byte |
| 217. | SBB L | 9D | 1 Byte |
| 218. | SBB M | 9E | 1 Byte |
| 219. | SBI Data | DE | 2 Bytes |
| 220. | SHLD Address | 22 | 3 Bytes |
| 221. | SIM | 30 | 1 Byte |
| 222. | SPHL | F9 | 1 Byte |
| 223. | STA Address | 32 | 3 Bytes |
| 224. | STAX B | 02 | 1 Byte |
| 225. | STAX D | 12 | 1 Byte |
| 226. | STC | 37 | 1 Byte |
| 227. | SUB A | 97 | 1 Byte |
| 228. | SUB B | 90 | 1 Byte |
| 229. | SUB C | 91 | 1 Byte |
| 230. | SUB D | 92 | 1 Byte |
| 231. | SUB E | 93 | 1 Byte |
| 232. | SUB H | 94 | 1 Byte |
| 233. | SUB L | 95 | 1 Byte |
| 234. | SUB M | 96 | 1 Byte |
| 235. | SUI Data | D6 | 2 Bytes |
| 236. | XCHG | EB | 1 Byte |
| 237. | XRA A | AF | 1 Byte |
| 238. | XRA B | A8 | 1 Byte |
| 239. | XRA C | A9 | 1 Byte |
| 240. | XRA D | AA | 1 Byte |
| 241. | XRA E | AB | 1 Byte |
| 242. | XRA H | AC | 1 Byte |
| 243. | XRA L | AD | 1 Byte |
| 244. | XRA M | AE | 1 Byte |
| 245. | XRI Data | EE | 2 Bytes |
| 246. | XTHL | E3 | 1 Byte |
You have seen opcodes of 8085 Microprocessor in the above table.
8 Bit Logical Compare Instructions
8 Bit Logical Rotational Instructions
16 Bit Arithmetic Instructions
Please explain the calculation of opcode interms of Hex values
Dear bali
HEX value are assigned by the INTEL CORPORATION corresponding to each instruction. There is no calculation related to it.
I hope you get the answer.
These hex values are further converted to decimals . The decimal values are further converted into signals. In order to perform the task given by the program the signals generated activates and deactivates the various small unit of microprocessor
.