Question

Explain the mechanism of generating physical/absolute address from segment

registers and offset by BIU of 8086

Answer 1

The mechanism of generating physical/absolute address from segment registers and offset by BIU of 8086 is as follows: segment value left-shifted by 4 bits, offset added to the segment value, and then passed to the MMU for conversion.

Step-by-step explanation:

To generate the physical/absolute address from segment registers and offset by the BIU (Bus Interface Unit) of the 8086 processor, the following mechanism is used:

1. The segment register value is left-shifted by 4 bits to obtain a 20-bit value.
2. The offset value is added to the 20-bit segment value to get the logical address.
3. The logical address is then passed to the memory management unit (MMU) which generates the physical/absolute address.

For example, let's say the segment register value is 0x1234 and the offset value is 0xABCD. The segment value (0x1234) is left-shifted by 4 bits to obtain 0x12340. Adding the offset value (0xABCD) to the 20-bit segment value (0x12340) gives us a logical address of 0x1D80D. This logical address is then converted to the physical/absolute address by the MMU.