Create a truth table for the logical OR operation.

A = uint8([0 1; 0 1]);
B = uint8([0 0; 1 1]);
TTable = bitor(A, B)

TTable = 2x2 uint8 matrix

   0   1
   1   1

bitor returns 1 if either bit-wise input is 1.

MATLAB® encodes negative integers using two's complement. For example, to find the two's complement representation of -5, you take the bit pattern of the positive version of the number (00000101), swap each bit (11111010), and then add 1 to the result (11111011).

Therefore, the bit-wise OR of -5 (11111011) and 6 (00000110) is -1 (11111111).

a = -5;
bitget(a,8:-1:1,'int8')

ans = 1×8

     1     1     1     1     1     0     1     1

b = 6;
bitget(b,8:-1:1,'int8')

ans = 1×8

     0     0     0     0     0     1     1     0

c = bitor(a,b,'int8')

c = -1

bitget(c,8:-1:1,'int8')

ans = 1×8

     1     1     1     1     1     1     1     1

Use bitor and bitshift to pack four 8-bit bytes into the 32-bit integer they make up.

Create four bytes of data. Specify the data with hexadecimal literals, using the -u32 suffix to specify that the data should be stored as uint32. Each byte contains 8 bits worth of data.

byte4 = 0x87u32; 
byte3 = 0x65u32; 
byte2 = 0x43u32; 
byte1 = 0x21u32;

Start by adding the first byte as the first 8 bits of a 32-bit unsigned integer.

packedNum = byte1;

Next, pack the other three bytes into packedNum, using bitshift to shift the bytes to the proper locations, and bitor to copy the bits over.

packedNum = bitor(packedNum,bitshift(byte2,8));
packedNum = bitor(packedNum,bitshift(byte3,8*2));
packedNum = bitor(packedNum,bitshift(byte4,8*3));

View the packed 32-bit integer.

format hex
packedNum

packedNum = uint32
   87654321