- bytes: Most computers use blocks of eight bits, called bytes, as the smallest addressable unit of memory.
- address: A machine-level program views memory as a very large array of bytes, referred to as virtual memory. And every byte of memory is identified by a unique number, known as its address. And the set of all possible addresses is known as the virtual address space.
- virtual address space: as indicated by its name, this virtual address space is just a conceptual image presented to the machine-level program. The actual implementation uses a combination of dynamic random access memory, flash memory, disk storage, special hardware, and operating system software to provide the program with what appears to be a monolithic byte array.
- program objects: program data, instructions, and control information.
A single bytes consists of 8 bits. In binary notation, its value range from 0000000 - 11111111. When viewed as a decimal integer, its value ranges form 0 - 255. But neither notation is convenient. Instead, we write bit patterns as base-16, called hexadecimal numbers.
And digits can be converted by referring to a chart:
| Decimal | Binary | Hex |
|---|---|---|
| 0 | 0000 | 0 |
| 1 | 0001 | 1 |
| 2 | 0010 | 2 |
| 3 | 0011 | 3 |
| 4 | 0100 | 4 |
| 5 | 0101 | 5 |
| 6 | 0110 | 6 |
| 7 | 0111 | 7 |
| 8 | 1000 | 8 |
| 9 | 1001 | 9 |
| 10 | 1010 | A |
| 11 | 1011 | B |
| 12 | 1100 | C |
| 13 | 1101 | D |
| 14 | 1110 | E |
| 15 | 1111 | F |
And there are some practice: 2.1
Then, if a value x is a power of 2, that is
Also, converting between decimal and hexadecimal representations requires using multiplication or division to handle the general case. We just need repeatedly divide x by 16, giving a quotient q and a remainder r, such that x = q * 16 + r. And to convert a hex number to decimal, we need multiply each of the hex digits by the appropriate power of 16. The practice is here: 2.3
Lastly, there are some arithmetic problems: 2.4