Memory Address Space and Data Organization | 8086 Microprocessor
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Memory Address Space and Data
Memory Address Space and Data Organization
Memory Address Space and Data Organization
The 8088 microcomputer supports 1 Mbytes of external memory.
The memory of an 8088-based microcomputer is organized as 8-bit bytes, not as 16-bit words.
Memory address space of the 8088/8086 microcomputer
3 Memory Address Space and Data Organization
The 8088 can access two consecutive bytes as word of data. Lower address byte and higher address byte The two bytes represent the word = 4 Memory Address Space and Data Organization
EXAMPLE What is the data word shown in the previous figure? Express the result in hexadecimal form. Is it stored at an even- or odd addressed word boundary? Is it an aligned or misaligned word of data? Solution: = FD16 = FDH = AA16 = AAH Together the two bytes give the word = FDAA16 = FDAAH Expressing the address of the least significant byte in binary form gives 0072BH = 0072B16 = , Therefore, it is misaligned word of data.
5 Memory Address Space and Data Organization
Even- or odd-addressed word If the least significant bit of the address is 0, the word is said to be held at an even addressed boundary.
Aligned word or misaligned word 6 Memory Address Space and Data Organization
A double word corresponds to four consecutive bytes of data stored in memory. Example of double word data is pointer. A pointer is a two-word address element that is used to access data or code in memory 7 Memory Address Space and Data Organization A pointer is a double word. The higher address word represents the segment base address while the lower address word represents the offset .
Memory Address Space and Data Organization
The 8088 microcomputer supports 1 Mbytes of external memory.
The memory of an 8088-based microcomputer is organized as 8-bit bytes, not as 16-bit words.
Memory address space of the 8088/8086 microcomputer
3 Memory Address Space and Data Organization
The 8088 can access two consecutive bytes as word of data. Lower address byte and higher address byte The two bytes represent the word = 4 Memory Address Space and Data Organization
EXAMPLE What is the data word shown in the previous figure? Express the result in hexadecimal form. Is it stored at an even- or odd addressed word boundary? Is it an aligned or misaligned word of data? Solution: = FD16 = FDH = AA16 = AAH Together the two bytes give the word = FDAA16 = FDAAH Expressing the address of the least significant byte in binary form gives 0072BH = 0072B16 = , Therefore, it is misaligned word of data.
5 Memory Address Space and Data Organization
Even- or odd-addressed word If the least significant bit of the address is 0, the word is said to be held at an even addressed boundary.
Aligned word or misaligned word 6 Memory Address Space and Data Organization
A double word corresponds to four consecutive bytes of data stored in memory. Example of double word data is pointer. A pointer is a two-word address element that is used to access data or code in memory 7 Memory Address Space and Data Organization A pointer is a double word. The higher address word represents the segment base address while the lower address word represents the offset .
4 سال پیش
در تاریخ 1399/09/12 منتشر شده
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