Here one can find complete instruction set of 8051 microcontroller. Complete information regarding each instruction like operational explanation, addressing mode, no. of byte occupied, no. of cycles used etc is given. So just, go through it. It’s a ready reference.
The complete 8051 Instruction Set or all 8051 instructions are broadly classify in to four groups data moving, logical, arithmetic and branching.
Data moving / handling Instructions:
| Mnemonics | Operational description | Addressing mode | No. of bytes occupied | No. of cycles used |
| Mov a,#num | Copy the immediate data num in to acc | immediate | 2 | 1 |
| Mov Rx,a | Copy the data from acc to Rx | register | 1 | 1 |
| Mov a,Rx | Copy the data from Rx to acc | register | 1 | 1 |
| Mov Rx,#num | Copy the immediate data num in to Rx | immediate | 2 | 1 |
| Mov a,add | Copy the data from direct address add to acc | direct | 2 | 1 |
| Mov add,a | Copy the data from acc to direct address add | direct | 2 | 1 |
| Mov add,#num | Copy the immediate data num in to direct address | direct | 3 | 2 |
| Mov add1,add2 | Copy the data from add2 to add1 | direct | 3 | 2 |
| Mov Rx,add | Copy the data from direct address add to Rx | direct | 2 | 2 |
| Mov add,Rx | Copy the data from Rx to direct address add | direct | 2 | 2 |
| Mov @Rp,a | Copy the data in acc to address in Rp | Indirect | 1 | 1 |
| Mov a,@Rp | Copy the data that is at address in Rp to acc | Indirect | 1 | 1 |
| Mov add,@Rp | Copy the data that is at address in Rp to add | Indirect | 2 | 2 |
| Mov @Rp,add | Copy the data in add to address in Rp | Indirect | 2 | 2 |
| Mov @Rp,#num | Copy the immediate byte num to the address in Rp | Indirect | 2 | 1 |
| Movx a,@Rp | Copy the content of external add in Rp to acc | Indirect | 1 | 2 |
| Movx a,@DPTR | Copy the content of external add in DPTR to acc | Indirect | 1 | 2 |
| Movx @Rp,a | Copy the content of acc to the external add in Rp | Indirect | 1 | 2 |
| Movx @DPTR,a | Copy the content of acc to the external add in DPTR | Indirect | 1 | 2 |
| Movc a,@a+DPTR | The address is formed by adding acc and DPTR and its content is copied to acc | indirect | 1 | 2 |
| Movc a, @a+PC | The address is formed by adding acc and PC and its content is copied to acc | indirect | 1 | 2 |
| Push add | Increment SP and copy the data from source add to internal RAM address contained in SP | Direct | 2 | 2 |
| Pop add | copy the data from internal RAM address contained in SP to destination add and decrement SP | direct | 2 | 2 |
| Xch a, Rx | Exchange the data between acc and Rx | Register | 1 | 1 |
| Xch a, add | Exchange the data between acc and given add | Direct | 2 | 1 |
| Xch a,@Rp | Exchange the data between acc and address in Rp | Indirect | 1 | 1 |
| Xchd a, @Rp | Exchange only lower nibble of acc and address in Rp | indirect | 1 | 1 |