Answer :
Address 0x23 contains 00H after assembling part (a), but if part (b) is assembled separately, it would instead contain 12H due to being part of the word at addresses 0x22 and 0x23 (123FH). However, if both are assembled together, part (b) would overwrite the data from part (a), resulting in an address 0x23 containing 12H.
In order to determine the contents of address 0x23 after assembling the given directives, we must consider the starting address specified by the ORG (origin) directive and the size of data defined by the DB (Define Byte) and DW (Define Word) directives.
For the first part (a) ORG 0x20 DB 00H, 05H, 07H, 00H, 03H, the DB directive defines a series of bytes. The starting address is 0x20, hence:
- 0x20 contains 00H
- 0x21 contains 05H
- 0x22 contains 07H
- 0x23 contains 00H
- 0x24 contains 03H
For the second part (b) ORG 0x20 DW 0702H, 123FH, 7020H, 0000H, the DW directive defines a series of words (2 bytes). This would overwrite the earlier bytes if assembled together as they have the same starting address. Assuming part b is assembled separately, we need to consider that each word occupies two bytes:
- 0x20 contains the lower byte of 0702H which is 02H
- 0x21 contains the higher byte of 0702H which is 07H
- 0x22 contains the lower byte of 123FH which is 3FH
- 0x23 contains the higher byte of 123FH which is 12H
If both parts are assembled collectively, address 0x23's content would be 12H due to the overwrite by part (b). However, if assembled separately, part (a) results in 0x23 containing 00H and part (b) results in 0x23 containing 12H.
