Bit Level Logical Instructions

Bit Level Logical Instructions

AU : May-08, 10, 11, 17, Dec.-18

Bit level manipulations are very convenient when it is necessary to set or reset a particular bit in the internal RAM or SFRs. The internal RAM of 8051 from address 20H through 2FH is both byte addressable and bit addressable. However, byte and bit addresses are different. The Table 15.6.1 shows the correspondence between byte and bit addresses.

As shown in the Table 15.6.1, addresses of bit 0 and bit 7 of internal RAM byte address 20H are 00H and 07H respectively. From Table 15.6.1 we can easily interpolate addresses of bit 1 and     bit 6 of internal RAM byte address 26H as 31H and 36H, respectively.  

Like internal RAM, some SFRs        are bit addressable. The Table 15.6.2 shows the bit     addressable  SFR and the corresponding bit addresses.

Table 15.6.3 gives the list of bit level operations.

Review Questions         

1. Name any four bit manipulation instructions in microcontroller 8051. AU ;     May-08     

2. What are the various operations performed by boolean variable instructions of 8051 ? AU : May-10     

3. What are the different operations performed by boolean variable instructions of 8051 ? AU : May-11,     Marks 2

4. What is meant by bit oriented instructions ? AU : May-17, :         Marks 2    

5. Explain the various bit manipulation instructions in 8051 with examples. AU : Dec.-18, Marks 13